tag:blogger.com,1999:blog-41931693067870794452024-03-05T20:01:16.553-05:00WAK'dWAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.comBlogger43125tag:blogger.com,1999:blog-4193169306787079445.post-31705142385796510482021-09-08T13:37:00.000-04:002021-09-08T13:37:12.432-04:00Indoor Carbon Dioxide Monitor<p> One might ask why someone would want to monitor the levels of carbon dioxide (CO2) in his or her indoor environment. Well, let me tell you about an article that I read in Make Magazine <a href="http://makezine.com" rel="nofollow" target="_blank">makezine.com</a>.</p><p>The article was written by Dale Dougherty and Guido Burger. The essence is that the concentration of CO2 can have a significant effect on the transmissibility of disease. Further, it can have an impact on people's mental acuity. </p><p>Let's look at these in turn. The authors cited an article titled <i>effect of ventilation improvement during a tuberculosis outbreak in underventilated university buildings </i> <a href="http://ncbi.nlm.nih.gov/pmc/articles/PMC7217216/" rel="nofollow" target="_blank">ncbi.nlm.nih.gov/pmc/articles/PMC7217216/</a> While I encourage you to read the article or at least the abstract, the conclusion was that some poorly ventilated rooms at the university were registering CO2 levels above 3,000 parts per million (ppm). When the levels were reduced to under 600 ppm the transmission of tuberculosis from the environment ceased. Of course this doesn't have anything directly to do with CO2 but rather measuring the concentration of CO2 is an easy way to determine how effectively the air is being turned over in an indoor environment. The concentration of CO2 in outdoor air is about 430 ppm.</p><p>The second article referenced was <i>Impact of CO2 on decision-making </i>Usha Satish, Mark j. Mendell, et al. 2012. <a href="http://doi.org/10.1289/ehp.1104789" rel="nofollow" target="_blank">doi.org/10.1289/ehp.1104789</a> This article found negative impacts on mental acuity that were caused apparently by the higher concentrations of CO2 found in some office environments.</p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdas9KlEZLCPrrZ_DeK23nQbwMkz9Flw9940m-P1UaISCZ4sXZAS9mTwSGfuqti4afqH0-z8gXrR97OTGEU8zQGQKm8ZN6F2h3LmurdLeIULpWgyULQf2BrFHvkGkuWFfxd6wqAYB7Z2w/s2048/IMG_3708.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdas9KlEZLCPrrZ_DeK23nQbwMkz9Flw9940m-P1UaISCZ4sXZAS9mTwSGfuqti4afqH0-z8gXrR97OTGEU8zQGQKm8ZN6F2h3LmurdLeIULpWgyULQf2BrFHvkGkuWFfxd6wqAYB7Z2w/s320/IMG_3708.jpg" width="320" /></a></div>Well, that's enough of that. I encourage you to read the papers but I found this interesting given the current discussions concerning school reopenings with high levels of Covid infections. One of my daughters is a teacher and I thought it would be interesting to build a CO2 monitor that she could place in her classroom. The article in Make Magazine that I mentioned above describes a wonderful assortment of form factors and displays for this type of device. I wanted to build something quickly for my daughter to use and made the device shown on the right. It shows the current CO2 concentration and every 15 seconds adds a bar to the graph. <p></p><p><br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirLDYpzpwiuj7tHbOIctJHKvZgiv98VZkfL2d_1EQSTfogko27WxpLL4GvKZ1wbaVSlgOc3x1vaw9oXS5oN437q-_sE4dhkweFPDnmXOWaybdyQptYE0xsK3mvbhzKDv_PxNGVf5B4Vns/s2048/IMG_3710.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirLDYpzpwiuj7tHbOIctJHKvZgiv98VZkfL2d_1EQSTfogko27WxpLL4GvKZ1wbaVSlgOc3x1vaw9oXS5oN437q-_sE4dhkweFPDnmXOWaybdyQptYE0xsK3mvbhzKDv_PxNGVf5B4Vns/s320/IMG_3710.jpg" width="320" /></a></div>Simple is the key word here. There is a microcontroller, a TFT display, a CO2 sensor, and connector to hook them together. <a href="http://adafruit.com" rel="nofollow" target="_blank">Adafruit</a> developed a standard for microcontroller shapes and pinouts such that anything that meets the "feather" standard can be plugged together. I happened to have a <a href="http://sparkfun.com" rel="nofollow" target="_blank">Sparkfun</a> esp32 Thing Plus, which adheres to the feather standard. This is a more powerful processor than that required for this project but, as I said I had it just sitting around. From Adafruit I ordered a "TFT FeatherWing 2.4in." display, an "SCD-40 True CO2" sensor and a "STEMMA QT / Qwiic" connector cable.<p></p><p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_QnC6pl8jFzr9pGsI2ob9CEelckGnJqmCmbVX7H901nTMTOD9eabqbJI2FaApeWdTut1hXu6NP7O42cCai0hTl9_GP5x732mnSl5zFBFRToU-AG66HksgUFOubg7QigQ8k3r8DuWYzgY/s2048/IMG_3712.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1536" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_QnC6pl8jFzr9pGsI2ob9CEelckGnJqmCmbVX7H901nTMTOD9eabqbJI2FaApeWdTut1hXu6NP7O42cCai0hTl9_GP5x732mnSl5zFBFRToU-AG66HksgUFOubg7QigQ8k3r8DuWYzgY/s320/IMG_3712.jpg" width="240" /></a>Once the parts arrived it literally took less than a minute to connect them together. The processor plugs into the back of the screen.</p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiY5Y0PUP7VR1WeEqugNKDKhkHHRdRIZnLtrG5KHSb8V9VSpx7FsxnW5eIFx3dBpnVYPZ3DVIbITW5X00Nj6d2yuYMtReheIRKsauJsllPo5VBVQkbf6SSwUBbqGzMJo9ziWyGVC9fMfK0/s2048/IMG_3713.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiY5Y0PUP7VR1WeEqugNKDKhkHHRdRIZnLtrG5KHSb8V9VSpx7FsxnW5eIFx3dBpnVYPZ3DVIbITW5X00Nj6d2yuYMtReheIRKsauJsllPo5VBVQkbf6SSwUBbqGzMJo9ziWyGVC9fMfK0/s320/IMG_3713.jpg" width="320" /></a></div>And they look like this when they're put together.<p></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJ2vQynSjjpdccjlqpq_QAh0lTQwLJsD7BgKn-1pYdht2tgbbVObsva5-OaZvjGc3l7wtykcNrn_du7tlWzOyA1bmj5e4oEepp_2x6XW7lUyReeLkhSrvTKsqz69tjrxCc7zbtlt5K_eo/s2048/IMG_3714.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJ2vQynSjjpdccjlqpq_QAh0lTQwLJsD7BgKn-1pYdht2tgbbVObsva5-OaZvjGc3l7wtykcNrn_du7tlWzOyA1bmj5e4oEepp_2x6XW7lUyReeLkhSrvTKsqz69tjrxCc7zbtlt5K_eo/s320/IMG_3714.jpg" width="320" /></a></div><br /><p></p><p><br /></p><p><br /></p><p>Then it was just a matter of plugging one end of the cable into the processor and the other end into the sensor.</p><p><br /></p><p><br /></p><p><br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuTjz0cM4Zph7nEawfCNOA2HWjHK0_qzHHmwK39MebtrsiJhboMzlVop8jnLu2QFddLvLPU3In4l8N4Y20QA-DsXkauSBVWk9__rNu6jD2-4seM6fzGneujiG50kC_5Rol069FhdKMXIw/s2048/IMG_3715.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuTjz0cM4Zph7nEawfCNOA2HWjHK0_qzHHmwK39MebtrsiJhboMzlVop8jnLu2QFddLvLPU3In4l8N4Y20QA-DsXkauSBVWk9__rNu6jD2-4seM6fzGneujiG50kC_5Rol069FhdKMXIw/s320/IMG_3715.jpg" width="320" /></a></div><p></p><p><br /></p><p><br /></p><p>I wrote the software in an afternoon with the help of the example program in the library that supports the sensor and the detailed Adafruit document that supports the display. Then I printed a case on my 3D printer and it was done. In the picture of the case you can see the little cage on the lower edge of the case back on the right in the picture. This is where the sensor sits so it is exposed to the air.</p><p><br /></p><p>I sent it off to my daughter and will post an update after she has had a chance to try it out.<br /></p><div class="separator" style="clear: both; text-align: center;"><div class="separator" style="clear: both; text-align: center;"><br /><br /></div><br /><br /><div class="separator" style="clear: both; text-align: center;"><br /><br /></div><br /></div><br /><div class="separator" style="clear: both; text-align: center;"><br /></div><br /><div class="separator" style="clear: both; text-align: center;"><br /></div><br /><br /><br /><p></p>WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com1tag:blogger.com,1999:blog-4193169306787079445.post-65840863725596302772021-03-10T14:43:00.000-05:002021-03-10T14:43:58.488-05:00Embroidery Floss Winder<div class="separator"><div style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><br /><br /></div></div><p></p><div class="separator" style="clear: both; text-align: left;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdZGx4OUKRIu0eaOdZTK7KdTFNOwEhl4UhPct57Z7REwl-pS14XfH2FSfKe3LqOE1U0VGsPICzLo8OiADpr6mJibMDLbzf0XRQmBwkUCteCv9-E7N0DdMkBIvKksJA-_QXX4ukpbYl1EQ/s320/IMG_5600.GIF" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="180" data-original-width="320" height="360" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdZGx4OUKRIu0eaOdZTK7KdTFNOwEhl4UhPct57Z7REwl-pS14XfH2FSfKe3LqOE1U0VGsPICzLo8OiADpr6mJibMDLbzf0XRQmBwkUCteCv9-E7N0DdMkBIvKksJA-_QXX4ukpbYl1EQ/w640-h360/IMG_5600.GIF" width="640" /></a></div><br />My daughter has a business via which she sells counted-cross-stitch kits, <a href="http://amazon.com/handmade/sewirreverent" target="_blank">Sew Irreverent</a>. The kits include a pattern and as many as a dozen different colors of floss. When she puts together these kits she needs to measure the amount of floss in each color to include, as well as wind the floss on a bobbin. As you can imagine this can be very time consuming.</div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;">She and I got our heads together and came up with the device shown here to facilitate the process. The heart of it is a small computer that allows her to specify how much floss she wants, and then starts and stops a small motor that winds the desired amount of floss onto a bobbin. Here it is in some more detail.<br /></div><p></p><p></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghkSzm84ONU5yRww-JilRUEYlwIk3-lbmAfYNAqrPlq_ZlKaXbq4in-5aTyTQFRJ7WjTnCPfrxl0OUpVMibQw9Kh2zYmfvRphaMb2FDsnz2KJkoEVwQE1ze5kIqu1aH-zGI889vKFml-Y/s2048/IMG_3211.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="2048" data-original-width="1536" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghkSzm84ONU5yRww-JilRUEYlwIk3-lbmAfYNAqrPlq_ZlKaXbq4in-5aTyTQFRJ7WjTnCPfrxl0OUpVMibQw9Kh2zYmfvRphaMb2FDsnz2KJkoEVwQE1ze5kIqu1aH-zGI889vKFml-Y/s320/IMG_3211.JPG" /></a></div><div><br /></div>To the right is a picture of the winder itself. The muscle is a small stepper motor designed to be controlled by a computer. Attached to the shaft of the motor is a cylinder with a slit in it and a peg. These hold the bobbin in place during the winding process. We found that some paper bobbins were a little too flexible to work well by themselves so we made a backer that can be seen in the lower left of the picture. This attaches to the cylinder via the peg and thus provides enough stiffness for the paper bobbins during winding but allows easy separation from the wound bobbin.<div><br /></div><div>In the upper center of the picture is just a simple guide through which the thread is passed before being attached to the bobbin for winding.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicQGStI9Aqv5a0FKhECR5-V0een9AWauwwvPxGMDxAJgi3l6dlAL05FKVUYOcfpCtHvJlOC9U9A42nQLhgHBs2ky_hb2YvZNujL1-UMI59EvpZSx3UKOp78vMGbN-6BcuUzgS4843BJgY/s2048/IMG_3216.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicQGStI9Aqv5a0FKhECR5-V0een9AWauwwvPxGMDxAJgi3l6dlAL05FKVUYOcfpCtHvJlOC9U9A42nQLhgHBs2ky_hb2YvZNujL1-UMI59EvpZSx3UKOp78vMGbN-6BcuUzgS4843BJgY/s320/IMG_3216.JPG" width="320" /></a><br /></div><div><br /></div><div>Here is the box that contains the tiny computer that controls the winder motor. In the upper right are the wires coming from the motor that connect to the computer.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQSNKyIDXTgg_tIokwDClg6uJr-xI1bBS-UnwVxdjH_0VrmR8rDVV11-pRVRFTPWu7Od__6cHJ9C2m27zI5a6Ftnhi7ctol5ITSXalWedqPg1AkCJ-ae4a_jmV30m0OZ3lx9GoDJOAi7o/s2048/IMG_3226.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQSNKyIDXTgg_tIokwDClg6uJr-xI1bBS-UnwVxdjH_0VrmR8rDVV11-pRVRFTPWu7Od__6cHJ9C2m27zI5a6Ftnhi7ctol5ITSXalWedqPg1AkCJ-ae4a_jmV30m0OZ3lx9GoDJOAi7o/w400-h300/IMG_3226.JPG" width="400" /></a></div><br /></div><div>This picture shows how the device is controlled. The large black button on the right is actually a little joystick. The diamond shape on the screen is the key for the user as to how to specify the length of floss to wind. The default is 3 yards. Pushing the joystick forward increases that number by 1. Pulling the joystick back decreases by 1. Right increases by 10 and left decreases by 10. Pushing downward on the joystick starts the winding process.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOFcQISar2OHCWDexodcN9tuQxsE7CQanYO2MRDqgvxS8br8VqBb8waIeW-LfXHjoTKsNcBfKCIIxLGkq-6vdStJ1JoDGKrXmWeFPn8yAgGvOAb_Rj5FatEIq7hXPeP2XI_ISjVT6NHRQ/s2048/IMG_3212.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOFcQISar2OHCWDexodcN9tuQxsE7CQanYO2MRDqgvxS8br8VqBb8waIeW-LfXHjoTKsNcBfKCIIxLGkq-6vdStJ1JoDGKrXmWeFPn8yAgGvOAb_Rj5FatEIq7hXPeP2XI_ISjVT6NHRQ/s320/IMG_3212.JPG" width="320" /></a></div><div><br /></div><div><br /></div><div><br /></div>We also added a couple of convenience features. The first is a tool for cutting the floss. It is a shroud that holds a standard single edge razor blade. This picture shows the blade being inserted into the shroud.<br /></div><div><br /></div><div><br /></div><br /><div><br /></div><div><br /></div><div><br /></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwmO1tsMfI7zahaCzK0tDMH1KuFQddZBl6fSNdRdBnkWZ8rJEGG9CZwzzr5eCsDqoy0Luu6DpIEdgYTR4S4s2_j0IYNTb0rb6X_6_sselhcI-ZWw1Ef66gfVSQdAo79i3Zw130xCshH_E/s2048/IMG_3229.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1536" data-original-width="2048" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwmO1tsMfI7zahaCzK0tDMH1KuFQddZBl6fSNdRdBnkWZ8rJEGG9CZwzzr5eCsDqoy0Luu6DpIEdgYTR4S4s2_j0IYNTb0rb6X_6_sselhcI-ZWw1Ef66gfVSQdAo79i3Zw130xCshH_E/w400-h300/IMG_3229.JPG" width="400" /></a></div><br /></div><div><br /></div><div><br /></div><div>And in this picture the blade is completely inserted, providing a V-shaped slot exposing a small amount of the blade for easy floss cutting but precluding any hand cutting.</div><div><br /></div><div>The second convenience feature can be seen in the upper left of this picture. It is a tape measure inlaid into the platform to facilitate any quick measurements.</div><div><br /></div><div><br /></div><div><br /></div><div><br /></div><div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrXWM3N2rRSKHSl37ClXnY7rakwnOlJrM9Q2ELOhd6qp9UXzjB1CcZTUSmTB26W2Kmsv56v-A9HD7QtwUV4zxoW-oUslYv_Tq_H0fTEqyR-XwefJ-BvCtH1jQz37wdMojJSaU4q6kX0gs/s2048/IMG_2763.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="1536" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrXWM3N2rRSKHSl37ClXnY7rakwnOlJrM9Q2ELOhd6qp9UXzjB1CcZTUSmTB26W2Kmsv56v-A9HD7QtwUV4zxoW-oUslYv_Tq_H0fTEqyR-XwefJ-BvCtH1jQz37wdMojJSaU4q6kX0gs/w300-h400/IMG_2763.JPG" width="300" /></a></div><br /></div><div><br /></div><div>Finally, here is the whole device as I was packing it up to send it to my daughter. In the back right of the device in the picture you can see the cone shaped pieces that take a standard size spool of embroidery floss.</div><div><br /></div><div>Well, that's it. If you have any questions please post them in the comments.</div><div><br /></div><div><br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKjwSKOmNOjG_BDfAF2FpEVcTv59aflGP3usLG-j6Rpudq7m_4NAzSeFfP-2oajkMQN0cmS6tgjD7gE4I6AiJEUvymH23CPh1PPeK4ScARWJ3K8epsUZmgnEM6Goi_4Z7Ke7dYnzLkggU/s2048/IMG_3212.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><div class="separator" style="clear: both; text-align: center;"></div></a></div><br /><br /><div class="separator" style="clear: both; text-align: center;"><br /></div><br /><br /><div class="separator" style="clear: both; text-align: center;"><br /></div><br /><br /> <p></p><br /></div>WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com2tag:blogger.com,1999:blog-4193169306787079445.post-52356407380754767672019-10-11T12:23:00.001-04:002019-10-11T12:23:29.915-04:00MIDI Self-playing Guitar (Part 3)Last time I told you about my failures in trying to fret guitar strings using a range of techniques. Now I will describe how I actually got it to work.<br />
<br />
I used the same method for controlling the vacuum that I described earlier. That is, solenoid valves were controlled by the Arduino Due. When an individual valve was opened it would apply a partial vacuum to a particular pneumatic.<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjh1GKKYe8y2ax79NLNGtBT6XSi2DiykezJml3eG-YKedH0hyOfBdoq5rFnypbPIknl1abbQd654kcP1ee6KMQe3YDC5_-Mp_MFrvXyDOyhP7kf8Uzcx9RVPBA6aFE83Uk2kfbV6B9M8YY/s1600/IMG_2797.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhz_ZJEhVU9-O03NDet1IQUKhjdP0RQcf2_Ksg3YGzhFzrVRy3YBGEY6nd0Z4lLCL73t9_H_AmMcGrYt3IaufC5w2R_RwjozO4z1iNTqfoA5dXXrQOA1WVBQ7_01jmU0L_DYI2HGOK6qXo/s1600/IMG_2797+unch.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="870" data-original-width="871" height="319" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhz_ZJEhVU9-O03NDet1IQUKhjdP0RQcf2_Ksg3YGzhFzrVRy3YBGEY6nd0Z4lLCL73t9_H_AmMcGrYt3IaufC5w2R_RwjozO4z1iNTqfoA5dXXrQOA1WVBQ7_01jmU0L_DYI2HGOK6qXo/s320/IMG_2797+unch.jpg" width="320" /></a>In the picture to the right you can see the plastic pipe that connects the vacuum pump to the solenoid valves, and thence to the pneumatics. Connected to each of the pneumatics is a wire. When the vacuum is applied to a particular pneumatic it pulls on the wire.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6RbaSB4IcyW5WD7Ulgsh3rWNzhyphenhyphenBx8xACSbTuV6ETbFuRdxuf4JHxvWlDBLUSAFDAjtrMkG9AZV3dN_02b0y5ZpQT2iuQI_bTWzIEtGvnK9RL66JI_mbQLE75ZhquX70Tc5qurHmLXjE/s1600/IMG_2794.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6RbaSB4IcyW5WD7Ulgsh3rWNzhyphenhyphenBx8xACSbTuV6ETbFuRdxuf4JHxvWlDBLUSAFDAjtrMkG9AZV3dN_02b0y5ZpQT2iuQI_bTWzIEtGvnK9RL66JI_mbQLE75ZhquX70Tc5qurHmLXjE/s400/IMG_2794.JPG" width="300" /></a></div>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_EUijIf6peAPuPpbY0j1Hx1QHajESPudbro5e6IWirwpjybgC_UkStl7c-_yjgguwOEFsCUMI6Zc_hYdkqy4waRRFeqG_G4ZNbwFzacj43ZY40QeqkMj4w0waVw5Tnj2Yk0ZzEthWjBM/s1600/IMG_2795.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj_EUijIf6peAPuPpbY0j1Hx1QHajESPudbro5e6IWirwpjybgC_UkStl7c-_yjgguwOEFsCUMI6Zc_hYdkqy4waRRFeqG_G4ZNbwFzacj43ZY40QeqkMj4w0waVw5Tnj2Yk0ZzEthWjBM/s400/IMG_2795.JPG" width="400" /></a><br />
Here is the attachment of the wire to the pneumatic. As you may be able to discern this is done through a turnbuckle that I 3D printed. The reason that I went to this trouble is that the length of the wire is critical as you can see in the next picture.<br />
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These are the "fingers" that actually press on the strings. The wires from the pneumatics attach to the top of the fingers. Pulling on the wire causes the lower end of the finger to push the string against the fret. As I said, the length of the wire is critical. That is because when the pneumatic is not activated the bottom of the finger must be well clear of string so as not to buzz or damp the string if it is plucked. On the other hand, it must be close enough to the string so that when the pneumatic is activated it presses firmly on the string.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2_XA1j3acxkvj-7V8y0hNCn2N_r1Z-VQM0y6OpqcuTyS1RgGO6BelvP0PuB9NNdiQU47uORuFbxhOMa4gQ37-9ViYz9F_rvKJFdgxKtq41LXMlmRRV4dJuc70z3_tCq9dOuFdgE-diH0/s1600/IMG_2797.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2_XA1j3acxkvj-7V8y0hNCn2N_r1Z-VQM0y6OpqcuTyS1RgGO6BelvP0PuB9NNdiQU47uORuFbxhOMa4gQ37-9ViYz9F_rvKJFdgxKtq41LXMlmRRV4dJuc70z3_tCq9dOuFdgE-diH0/s400/IMG_2797.JPG" width="300" /></a></div>
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And here is what it looks like overall. The silver wires from the twenty-three pneumatics lead to the compressed space where the corresponding fingers hover about the fret board. Thus, twenty-three fretted strings plus six open strings gives twenty-nine notes or about two and one-half octaves.<br />
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And once again<a href="https://www.youtube.com/watch?v=No0-5EEAkrs" target="_blank"> here is the link to a quick video </a>that might help to understand how it all goes together in case my explanation is lacking.WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-88589659999172776752019-09-24T11:24:00.003-04:002019-09-24T11:24:43.683-04:00MIDI Self-playing Guitar (Part 2)<br />
This is a continuation of the description of the design of my MIDI guitar. In the first part I explained how I handled the picking of the strings. Here I will explain the process I went through to handle fretting.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgm58_sMDQeSRrxEb2cODUI1qsL3gqS-pDRfbvkzCBrtFBT7SAs4mylmxGHd-XkxmLYH9GkAS62Ex38bGF-xiXZ4rukxJkGtj6S7qSqA5Xy6Hb9-u5SyjTBdkxfpJlfIX7lAjOXVAQ005M/s1600/IMG_2172.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgm58_sMDQeSRrxEb2cODUI1qsL3gqS-pDRfbvkzCBrtFBT7SAs4mylmxGHd-XkxmLYH9GkAS62Ex38bGF-xiXZ4rukxJkGtj6S7qSqA5Xy6Hb9-u5SyjTBdkxfpJlfIX7lAjOXVAQ005M/s400/IMG_2172.JPG" width="300" /></a>I had used solenoids on the organ and thought that would
be a good idea for the guitar as well. Space is tight on the neck of a
guitar but my plan was to use levers to transfer the motion from the
solenoids into the tight confines of the fret board. Here are pictures of a prototype. <br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4_Q-_OBeBQrQ_M5zMqAOE7rAdlVXJKi5Sq-vtFI_9JqmGdwE1vdxIvn0n8r-7qOADrAlzxkA82Pk6b41t20M2CmcaNk6vuoLRxwTb-oY8-aOWwv95Z0eSo_SUrHrepgavPmiEf03seog/s1600/IMG_2181.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4_Q-_OBeBQrQ_M5zMqAOE7rAdlVXJKi5Sq-vtFI_9JqmGdwE1vdxIvn0n8r-7qOADrAlzxkA82Pk6b41t20M2CmcaNk6vuoLRxwTb-oY8-aOWwv95Z0eSo_SUrHrepgavPmiEf03seog/s320/IMG_2181.JPG" width="320" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4GSc6KO0kEcsGyhnpY-wI-qTvIBQOtGSu-GaBHHdbI_PwZmK9Dc58oK44yDmJ5mfuN0lOktQBHCu_f0IEBz850ccs5JTkzzu9qwRIoroMrL4nsTKUgmzWIXfY8qHUNBFAKPO45nLhteg/s1600/IMG_2182.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4GSc6KO0kEcsGyhnpY-wI-qTvIBQOtGSu-GaBHHdbI_PwZmK9Dc58oK44yDmJ5mfuN0lOktQBHCu_f0IEBz850ccs5JTkzzu9qwRIoroMrL4nsTKUgmzWIXfY8qHUNBFAKPO45nLhteg/s320/IMG_2182.JPG" width="320" /></a>Another advantage of the levers was that I
could trade-off stroke length and force by moving the pivot point of the
lever. Unfortunately my solenoids didn't have enough inherent stroke
and power to both firmly press the string against the fret as
well as withdraw far enough such that they did not interfere with the
vibrating string. I tried many different pivot positions but none proved
to be dependable enough to satisfy me.<br />
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While mulling
this problem I happened to think of player pianos. They need a long
powerful stroke, especially on the lower keys. And they trigger those
key presses via a tiny amount of air drawn through holes in a paper
roll. I didn't know how they worked so once again I matriculated at the
University of YouTube.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7PeHRndMngI1I3KQFn2Yb8bqaJdGTI-OELvrfL5XoSwk8NVDLwexIhe6cr0g_bUSF2ZTtRu8CDQ4L95CQSJ0DdfwGSXPBTjEjx9iYzltOEyAyk-wWevZ3Wtsq8tZ0m70ObVkl_iGMdNY/s1600/IMG_2566.JPG" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7PeHRndMngI1I3KQFn2Yb8bqaJdGTI-OELvrfL5XoSwk8NVDLwexIhe6cr0g_bUSF2ZTtRu8CDQ4L95CQSJ0DdfwGSXPBTjEjx9iYzltOEyAyk-wWevZ3Wtsq8tZ0m70ObVkl_iGMdNY/s320/IMG_2566.JPG" width="320" /></a><br />
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I found that they used pneumatics designed like little bellows. Here are pictures of the bottom and top of one I made to experiment with. In the first picture the large hole on the right goes through to the inside of the pneumatic. When that hole is connected to a vacuum pump it sucks the top of the device down. However, I needed something to open it back up when the vacuum was removed. I thought about various types of springs, both internal and external. Ultimately, though, I decided to use rare earth magnets. That's what the large blind holes on bottom and top are for. I glued magnets into each of those, with common poles facing each other so they repelled. That seemed to do the trick.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJqk8b-vAtNXdIkADUSM_W3tWYbRTuwP1QM1Ha8jumjU8OQufwHVe89iFj6R-qKF04Lt1RyrjkcGD9xUPb9bVQb0UVdMnZ9TeN30bXjtcYPKwXfn3Hr0LpUHHC1CAKDPv-hQh9AmzcPqU/s1600/IMG_2569.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJqk8b-vAtNXdIkADUSM_W3tWYbRTuwP1QM1Ha8jumjU8OQufwHVe89iFj6R-qKF04Lt1RyrjkcGD9xUPb9bVQb0UVdMnZ9TeN30bXjtcYPKwXfn3Hr0LpUHHC1CAKDPv-hQh9AmzcPqU/s320/IMG_2569.JPG" width="320" /></a>One of the advantage of these pneumatics is that their throw and force can be adjusted by simply changing their size. I made mine about four inches long and one inch wide, which I think is a typical size for
pianos. The purple stuff is a synthetic
bellows cloth made specifically for player pianos. <br />
It is pretty
air-tight, cuts and glues easily, and is thin and flexible enough to
fold well. The
small hole on the top is to bleed air back into the pneumatic allowing
it to expand when the vacuum is no longer connected. The small holes on the bottom are just screw holes drilled for various prototype configurations.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2Gwti3EkhXkK0dhcHNXeb9Jd3WPRq1caTKGcTw13UzSV6HekPvIaQJ24WkQ1ldlF5ZKrzq4RAvhmfUi6Kth5ctVgVTqqCOzmMcM_tHm7NHkma6Mp3Q-LKVceXxiFwwEJ83m6qXbj2o48/s1600/IMG_2565.JPG" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2Gwti3EkhXkK0dhcHNXeb9Jd3WPRq1caTKGcTw13UzSV6HekPvIaQJ24WkQ1ldlF5ZKrzq4RAvhmfUi6Kth5ctVgVTqqCOzmMcM_tHm7NHkma6Mp3Q-LKVceXxiFwwEJ83m6qXbj2o48/s320/IMG_2565.JPG" width="320" /></a><br />
But
how do you connect and disconnect the vacuum you might ask. I thought I
would use these solenoid operated valves that I got from <a href="http://adafruit.com/" target="_blank">Adafruit.com</a> for another project that has not yet come to fruition (no pun intended). In player pianos they often use these beautiful little valves that are themselves operated by pneumatics, triggered by the air flowing through the little hole in the paper of the piano roll, but I would have had to used little solenoids, which I didn't have, and which would have cost almost as much as the valves, which I did have. This decision led to a completed device that more or less dwarfs the guitar itself, but more on that later.<br />
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Next I had to figure out how the pneumatics would actually push the strings down onto the frets.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFn0NFQhpe49p5JPz_3sQrWTNbQTSnE4XdbK24Il6ntBcwISIR9OcTlb7s5OyxDoChFfl4XjrhXfawKXGztujGiirjE0gpBrsGQKJjAYZm_Yhd8clT1K1N2APABwMM_vXXQkqH9exU0ok/s1600/IMG_2522.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="480" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFn0NFQhpe49p5JPz_3sQrWTNbQTSnE4XdbK24Il6ntBcwISIR9OcTlb7s5OyxDoChFfl4XjrhXfawKXGztujGiirjE0gpBrsGQKJjAYZm_Yhd8clT1K1N2APABwMM_vXXQkqH9exU0ok/s640/IMG_2522.JPG" width="640" /></a></div>
I thought a good idea would be to drill holes in the fret board and mount the pneumatics under the neck of the guitar. I then connected a wire and ran it up through the hole and put a little 90-degree bend in the end. To that bend I added a little 3d printed plastic button. Those buttons were kind of noisy so I added a wrap of leather around the button. Good idea, huh? Well, not so much. This scheme had the advantage that as it played it was easy to observe the fretting of the strings. The major disadvantage was that things were so packed together that it was very difficult to fit the wires, and there wasn't room to squeeze in adjusters for the wire lengths. The length of the wire is critical because the button must rise high enough when that pneumatic is not activated so the string doesn't buzz against it, yet pull down far enough to press the string firmly against the fret when the pneumatic is triggered. I spent approximately 142 man-years trying to get them all adjusted, finally considering using a sledge hammer as an adjustment tool, and ultimately falling back to re-group.<br />
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OK, that's it for this episode. In the next one I'll describe my perhaps ungainly but more or less successful solution. Thanks for your interest. <br />
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<br />WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-47825465570109707662019-09-01T11:12:00.002-04:002019-09-01T11:12:49.651-04:00MIDI Self-playing Guitar (Part 1)I enjoyed making the MIDI Pipe Organ that I described in earlier posts on this blog titled Music & Me Parts 1 through 5. I brought the Organ to a couple of Orlando (Fla.) Maker Faires. It was well received. In fact, the second year that I went a couple of people told me that they came back looking for the Organ specifically, having seen it the previous year. The problem is that the Organ has forty-two separate pipes, plus the wind chest/base, plus the blower. It's heavy to move around, and time consuming to set up and take down, and complicated to transport. I thought I'd try to make something a little more portable, and a guitar came to mind. That was my first mistake.<br />
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Here we are, two years later, and only now are things starting to come together. I can, however, tell you a bunch of ways <u>not</u> to make a self-playing guitar. Before I get into my story, though, I have posted a rough video on YouTube for those of you who want to hear the guitar but aren't interested in how I got there, and you can see it <a href="https://www.youtube.com/watch?v=No0-5EEAkrs" target="_blank">here</a>. (I will also work on my spelling.)<br />
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There are, of course, two parts (hands) involved in playing the guitar, the picking typically done with the right hand, and the fretting typically done with the left. While I worked on these concurrently I think the story will be easier to follow if I talk about the picking first, and then the fretting.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCnWymXGuKpNAUwXrnVK7UhR-uoweW-R3RDTN_SBkajcxBxQoZdO_0kVRwNtbw2CHVcuXzDXUvWg6M6rIjpF3br40nn7kkgECvKz2vinyInbXYZ1ATiz2tz2ebmp6fhbC6oWmYq6q36bs/s1600/IMG_2178.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCnWymXGuKpNAUwXrnVK7UhR-uoweW-R3RDTN_SBkajcxBxQoZdO_0kVRwNtbw2CHVcuXzDXUvWg6M6rIjpF3br40nn7kkgECvKz2vinyInbXYZ1ATiz2tz2ebmp6fhbC6oWmYq6q36bs/s320/IMG_2178.JPG" width="320" /></a></div>
This was one of my early attempts. I used hobby servos, attached arms to them, and attached guitar picks to the arms. The problem I had here was that sometimes the pick would bend, but not snap over the string. I would then lengthen the stroke. Unfortunately, if the arm swung far enough to pluck the string often the pick would wind up in contact with the adjacent string.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGVH4LN1qSmxRaZ_OlMpFE6yWdFEZVJ11euUdRyCR6DIyPVyf5Wf7H-RQ0vJpjTLZzqM-0H2MX6Xhsd0lokfYLtEjNNrevS7V_qAYeHkBMtI_JW2-YJSjOHYtmS_rqYeAYBC7VggtYx0g/s1600/IMG_2520.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGVH4LN1qSmxRaZ_OlMpFE6yWdFEZVJ11euUdRyCR6DIyPVyf5Wf7H-RQ0vJpjTLZzqM-0H2MX6Xhsd0lokfYLtEjNNrevS7V_qAYeHkBMtI_JW2-YJSjOHYtmS_rqYeAYBC7VggtYx0g/s320/IMG_2520.JPG" width="320" /></a>OK, no problem. I would just make the picks stiffer so they wouldn't bend so much. Here is a picture of the next version. That seemed to work pretty well, until I started fretting the strings. Because there was no flex in the picks their positioning was critical. If they caught too much string they would just drag the string along with them. If the strings were open (unfretted) they worked fine. However, when they were fretted the string would be pushed closer to the guitar and the pick would barely catch the string or miss it completely. I was not able to find a setting that worked consistently.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhW0BxTKXN6OlG6m6hHY-yjUmT2snuC25rH5sa0ngy-EKtv2B5W3mCrXYWyPWta4UkrKu38WE89bKUUaSW0SaYZifSjjIKd1e1514DskdwcLzQmoqKyo5at7D1fzUCqOoYKiJLcbDG1Ncg/s1600/ServoPicks.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhW0BxTKXN6OlG6m6hHY-yjUmT2snuC25rH5sa0ngy-EKtv2B5W3mCrXYWyPWta4UkrKu38WE89bKUUaSW0SaYZifSjjIKd1e1514DskdwcLzQmoqKyo5at7D1fzUCqOoYKiJLcbDG1Ncg/s1600/ServoPicks.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="560" data-original-width="757" height="295" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhW0BxTKXN6OlG6m6hHY-yjUmT2snuC25rH5sa0ngy-EKtv2B5W3mCrXYWyPWta4UkrKu38WE89bKUUaSW0SaYZifSjjIKd1e1514DskdwcLzQmoqKyo5at7D1fzUCqOoYKiJLcbDG1Ncg/s400/ServoPicks.jpg" width="400" /></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh09l7hsUod9Qg3H7Ir_-5LuHkLdJi5nU_FueBBLTGHUu4B_qPYOqebYpAAIJ8-T7Vkcz5w6pUhaRJjwRaorb6Y3FbEdoTnldrdKlL7XfhyHmYKlorT_Eue8RtFYT9Ed7l68nV8LQAqsYw/s1600/IMG_2546.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh09l7hsUod9Qg3H7Ir_-5LuHkLdJi5nU_FueBBLTGHUu4B_qPYOqebYpAAIJ8-T7Vkcz5w6pUhaRJjwRaorb6Y3FbEdoTnldrdKlL7XfhyHmYKlorT_Eue8RtFYT9Ed7l68nV8LQAqsYw/s320/IMG_2546.JPG" width="320" /></a></div>
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So next I went back to the flexible picks. But this time I changed the mechanics. Here is a drawing that might help me explain. The blue boxes are the servos, the red lines are the picks. The black dots are meant to represent the six strings of the guitar, but try to picture that you are looking right down the string, such that it is coming out of the page. If you can picture that you can see that when the pick is swung to the left as in Position 1 it doesn't interfere the the next string. As the pick starts to swing it will hit its string as in position 2. Finally, in position 3 it can't interfere with the string on the other side.<br />
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This scheme still requires careful adjustment of the height of the picks but they can be set such that they consistently pick an open or fretted string without coming in contact with adjoining strings.<br />
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Alright, so that's the design that settled on for picking the strings. Ultimately the speed of the guitar will be limited by (among other things) the speed of the servos and the lengths of the strokes. I don't think I'll be able to compete with Slash or Jimmy Page but as the Brits say, "The best is the enemy of the good."<br />
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In my next post I'll fret about fretting. <br />
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<br />WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com2tag:blogger.com,1999:blog-4193169306787079445.post-23342192574791266762018-08-09T09:07:00.003-04:002018-08-09T09:07:50.792-04:00Electronic Musical ToyThere is an article on the makezine.com website <a href="https://makezine.com/2017/11/13/building-a-secret-backstage-wall-piano-for-a-concert-venue/" target="_blank">here</a> written by Gareth Branwyn. It tells of a project built by Martin Hertig. It is essentially a one octave electronic musical instrument that Mr. Hertig built to be installed backstage at the concert venue Jugendkulturhaus Dynamo. I have a young grandson and I thought he might enjoy playing with something like that so I decided to build one. Here is my version, standing on the shoulders of Martin Hertig.<br />
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As in the original, rather than buttons, I wanted it to be touch sensitive. Here, as has happened many times in the past Adafruit came to my rescue with the "Adafruit 12-key Capacitive Touch Sensor Breakout - MPR121" that can be found <a href="https://www.adafruit.com/product/1982" target="_blank">here</a>. It is a nifty little device that can sense touch on twelve different lines, with millions of adjustments (of course that can be good and bad) to control how it acts. This device can communicate with little computers via I2C (Inter-Integrated Circuit) a protocol that is supported by lots of devices including Arduino, Raspberry Pi, etc.<br />
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My thinking was this. I wanted a full chromatic octave, twelve notes, plus I wanted some non-chromatic percussion, drums and so forth. Also I wanted to be able to adjust the octave up or down that the twelve notes played. Finally, I wanted to change the instrument whose sound was emulated by the device. All that meant I would need two of the 12-key touch sensors.<br />
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I also needed a device that could generate the sounds of the notes and different instruments. Yet again, Adafruit bailed me out, this time with the <span style="background-color: white; font-family: inherit; letter-spacing: 0.28px;">"Adafruit "Music Maker" MP3 Shield for Arduino w/3W Stereo Amp - v1.0" found <a href="https://www.adafruit.com/product/1788" target="_blank">here</a>. This item, among lots of other functionality, has a midi synthesizer (and I know midi from my pipe organ project) as well as a 3-Watt amplifier that can be connected directly to speakers. Further, it is an Arduino shield so it plugs right into an Arduino Uno, which of course speaks I2C. Sometimes things just work out.</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj03nz9ShCb4Vyi0ZKPAEBJsVdJGXctkFMmKI2KNR7-2drFYkrkZpWm66qUBq1tHrF4uyL3R3V95io0qqAYhNlgFIC6sz8mfE2JVDTs2-5khGOwwLdgDmJ5Gv-6qlpkvK862NB3fzyyi38/s1600/IMG_2186.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1600" data-original-width="1600" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj03nz9ShCb4Vyi0ZKPAEBJsVdJGXctkFMmKI2KNR7-2drFYkrkZpWm66qUBq1tHrF4uyL3R3V95io0qqAYhNlgFIC6sz8mfE2JVDTs2-5khGOwwLdgDmJ5Gv-6qlpkvK862NB3fzyyi38/s320/IMG_2186.JPG" width="320" /></a><span style="letter-spacing: 0.28px;"><br /></span><br />
<span style="letter-spacing: 0.28px;">And here it is. The knobs at the top are the percussion. The twelve handles are one chromatic octave, arranged like a piano keyboard. The two knobs on the left shift the notes up or down one octave. And the knob on the right changes the instrument that is being emulated.</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLCn2SnR5ysn0vI3TLXGHLWm4xzSv9zrXxasFGmhbvgVtZCZ8YhrxLKuJz_Krb-Je6HNnMsrezWbuz8CnTIYo_Xv6DBspVD_bpZTGFxBb_TBe9k6yYgC7HTR4s6Sclzp9UnjtFZk0bDg8/s1600/IMG_2187.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1600" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLCn2SnR5ysn0vI3TLXGHLWm4xzSv9zrXxasFGmhbvgVtZCZ8YhrxLKuJz_Krb-Je6HNnMsrezWbuz8CnTIYo_Xv6DBspVD_bpZTGFxBb_TBe9k6yYgC7HTR4s6Sclzp9UnjtFZk0bDg8/s320/IMG_2187.JPG" width="320" /></a></div>
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<span style="letter-spacing: 0.28px;">This is what it looks like with the back removed. In the lower right is the Arduino Uno with the Music Maker shield on top. Next to it are the Capacitive Touch Sensors. Besides that just speakers and wire.</span><br />
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<span style="letter-spacing: 0.28px;">I posted a video on YouTube <a href="https://youtu.be/IKJbyk03BjA" target="_blank">here</a> in case you want to see it play.</span><br />
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WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-19214175542617173322018-05-26T17:06:00.002-04:002018-05-26T17:06:37.070-04:00Indirect Ophthalmoscopy Using a Raspberry Pi -- Part 2As I discussed in my earlier post on this topic, my brother and I are attempting to build an inexpensive, easy to operate, fundus camera that can be used to screen for diabetic retinopathy. Also as I said earlier, we didn't have much luck with a device I built by stacking up a raspberry pi camera, a raspberry pi, and a 7" touchscreen. Therefore we took a new approach.<br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="clear: right; float: left; margin-bottom: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSLMi78fOtz5EVrbRc91HhkmnKQo1vK6VS4O3iohunfHbgCBuGcYG5Vp5u7QxThNMEuKhiEWvlQ6whHSW_L5v9J4KeUh0hhWEC-NaKNCVeKUEs3DfliwnBwQp1NjE5Z01Pl2JivBY26EU/s1600/IMG_2191.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1600" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSLMi78fOtz5EVrbRc91HhkmnKQo1vK6VS4O3iohunfHbgCBuGcYG5Vp5u7QxThNMEuKhiEWvlQ6whHSW_L5v9J4KeUh0hhWEC-NaKNCVeKUEs3DfliwnBwQp1NjE5Z01Pl2JivBY26EU/s400/IMG_2191.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Optical bench showing various adjustments</td></tr>
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I built an optical bench that allowed many adjustments for the distances and alignments of the components. It held the camera, the LEDs to illuminate the eye, the 20 diopter condensing lens, and the patient's head. The Raspberry Pi and some other components were attached to one or another of these devices via cables. Let me talk about these things in turn.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO0UBwtvF1zedzz80X38_ERbKBJKFHBPQt1uDF9YGnHYbQMeEWQSbQ4vZOO6xHUyhZk4_tcdC21MwUeZNi0tOOPxT6e1-Xir22SFnXPXEzO-MLWsmhD7jfLRg8RO30eRui_PgZYsd0RwE/s1600/IMG_2194.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO0UBwtvF1zedzz80X38_ERbKBJKFHBPQt1uDF9YGnHYbQMeEWQSbQ4vZOO6xHUyhZk4_tcdC21MwUeZNi0tOOPxT6e1-Xir22SFnXPXEzO-MLWsmhD7jfLRg8RO30eRui_PgZYsd0RwE/s320/IMG_2194.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Camera with adjustable focus lens and LED board ahead of it</td></tr>
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<b>Camera </b>-- We did not actually use the official Raspberry Pi camera. The official camera has a fixed lens. That is, it is not meant to have its focus changed from its factory setting, which is more or less at infinity. We want to be able to focus more effectively on nearby objects. The lens can actually be turned using a pair of tweezers and thus the focus can be brought nearer but this is a fiddly process, and not very convenient. Instead we used a camera sold by UCTronics. It uses the same sensor as version 2 of the Pi Camera but has a lens that can be easily focused manually. I purchased an extra long camera cable from Adafruit allowing me to mount the camera on the bench and still reach the Pi.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhiZbtZy5JAaBGAgHcr0anwCUhfLg73cSCPRKqydLOUu8PiEw0dQEKpmBpMXL_88wBB19dw88d2zBspAh2aO4BPa-546N5LuP9Dw1JYbhLXcGAmfnSJFxgHmjstQrZolI4YdNMd-TT6Ss/s1600/IMG_2222.JPG" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1200" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhiZbtZy5JAaBGAgHcr0anwCUhfLg73cSCPRKqydLOUu8PiEw0dQEKpmBpMXL_88wBB19dw88d2zBspAh2aO4BPa-546N5LuP9Dw1JYbhLXcGAmfnSJFxgHmjstQrZolI4YdNMd-TT6Ss/s400/IMG_2222.JPG" width="300" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Board containing prototype bi-color LEDs</td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWo7SifY08mzdqS0oE6I-9G3bU5biODvxNzLVCcW5aSc7eNq1D-qVNs3S-P3tCXLM4Mtjbw5IVJKGDt_0La2y8nxH0zVoAXxYCeCY4d_pqQOhrRy9KcG-swB_vu_xhPN7HipTIdJJ7YvA/s1600/IMG_2223.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1200" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWo7SifY08mzdqS0oE6I-9G3bU5biODvxNzLVCcW5aSc7eNq1D-qVNs3S-P3tCXLM4Mtjbw5IVJKGDt_0La2y8nxH0zVoAXxYCeCY4d_pqQOhrRy9KcG-swB_vu_xhPN7HipTIdJJ7YvA/s400/IMG_2223.JPG" width="300" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Board containing conventional LEDs</td></tr>
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<b>LEDs </b>-- I built two versions of the board containing the LEDs. One contained two of bi-color prototype LEDs (white and infrared) that I mentioned last time, and one contained two each of conventional through-hole white and infrared LEDs. Through experimentation we found that a single LED of each type was able to provide sufficient light. The reason we decided to have two, at right angles to each other, is an attempt to overcome specular reflection from the various optical components. The highlights of these LEDs potentially hide important information in the image so we felt it was important to deal with it. More about that later. There is a ribbon cable that runs from the LED board to a breadboard that contains the circuitry that drives the LEDs based on control signals from the Pi. There are also two potentiometers that can be used to control the brightness of the LEDs.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkfOSM5Bf7Yn9kMmcfViJ6lJs_0hvrcXjn3rZfgzs9mkwBW_qVuMR-l0Cmhvpj2KEG46roep8GHMIhbXOf8t22B5MCouwO-Oxe8B3Vb-8A595DdVqIC-1ccLl12cN5RQ10USrqdDo4VJQ/s1600/IMG_2195.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1600" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkfOSM5Bf7Yn9kMmcfViJ6lJs_0hvrcXjn3rZfgzs9mkwBW_qVuMR-l0Cmhvpj2KEG46roep8GHMIhbXOf8t22B5MCouwO-Oxe8B3Vb-8A595DdVqIC-1ccLl12cN5RQ10USrqdDo4VJQ/s400/IMG_2195.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Infrared and White LED brightness controls</td></tr>
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<b>Condensing Lens</b> -- This lens provides the primary magnification for the image of the retina. Other focal length lenses are sometimes used but this seems to be the most common for this type of screening test.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBRvOVN6VHA1Xfx9dqXZImmfhYbj7BBMQTwFZ_-au8QLtF8gtDYjVWPaLgUHJLF4jtemReK852uFd9cAdsOb4B_HoIUzCL_LmmNkF6_vj9I76cS6hPvdbSHxOUh3tzifVMMlCk99kSpDE/s1600/IMG_2193.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBRvOVN6VHA1Xfx9dqXZImmfhYbj7BBMQTwFZ_-au8QLtF8gtDYjVWPaLgUHJLF4jtemReK852uFd9cAdsOb4B_HoIUzCL_LmmNkF6_vj9I76cS6hPvdbSHxOUh3tzifVMMlCk99kSpDE/s320/IMG_2193.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Chin and head rest as well a condensing lens</td></tr>
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<b>Patient Fixture</b> -- This is simply an adjustable chin rest and head rest meant to hold the patient's head in a fixed position.<br />
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<u>Hardware</u> -- We used a Pi 3 Model B Version 2. Using GPIO pins it is connected to the circuit board that drives the LEDs mentioned above. It is also connected via USB cable to an Arduino. We wanted the ability to control a number of Pi Camera parameters on the fly. (See <u>Software</u> below) We did this by using four potentiometers as voltage dividers, read the voltage via the analog to digital converters on the Arduino, and then pass that information to the Pi via the USB.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj01QA4sF3rm1eYXYru3SwdNCOOjnFOhgnZyl2KELf4FLXGuO4sHw5cHY0nQ0uqgW-AV0Qe1Ww5Pa4yNkpagUNt3rjpX3i-8WuVa6oMQETkAXAuvf3aOouXhyEN_1BM67IqVDOCLR-H9p8/s1600/IMG_2196.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj01QA4sF3rm1eYXYru3SwdNCOOjnFOhgnZyl2KELf4FLXGuO4sHw5cHY0nQ0uqgW-AV0Qe1Ww5Pa4yNkpagUNt3rjpX3i-8WuVa6oMQETkAXAuvf3aOouXhyEN_1BM67IqVDOCLR-H9p8/s320/IMG_2196.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Brightness, Contrast, Sharpness and ISO camera controls</td></tr>
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<u>Software</u> -- The Pi is programmed using Python. The program starts out (using the Python camera interface) to set up a camera preview and then enters a tight loop reading the desired settings for brightness, contracts, sharpness, and ISO from the Arduino based on the positions of the potentiometers. It sets the given parameters in the camera software and then loops back to read the information from the Arduino again. There is a normally open button connected to a GPIO pin on the Pi that works as a shutter button. When a button is pushed an interrupt on the Pi is triggered. The Pi takes a picture, turns off the preview, and displays the picture in a browser window on the Pi. When the shutter button is pushed again the camera preview is re-enabled and the process starts over. The pictures are numbered consecutively so they are not overwritten. Using hardcoded variables in the Python program the action of the LEDs can be controlled. For instance, the eye can be illuminated in IR during the preview but have the white LED flash as the picture is taken. Or the eye can be illuminated in white light during the preview and when the picture is taken. Or it can be illuminated in IR continuously. Or no illumination can be provided.<br />
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Here is an example of a picture we took using our device. The optic nerve is the yellow circular area in the upper left of the picture. This picture is not perfect, of course. You can see evidence of the specular reflection I mentioned earlier. We are, however, pleased with the resolution and the field of view. Also we still haven't been able to achieve sharp focus using the IR LEDs so it should be noted that this photo is taken with a chemically dilated pupil.<br />
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Next time I'll talk about what we're doing about that.<br />
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Oh, and one other thing. There is a group that has made excellent progress on this type of device. If you're interested in the topic be sure to look <a href="http://www.instructables.com/id/Open-Indirect-Ophthalmoscope-OIO/" target="_blank">here</a>.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgndOjvfEKuA3kNmQDEjUkPcOLYhMaJWl8OjcNU_Q3X0wzCIHnVJzCVlphgYk24h3XbLIelvMORlxHu11lvArmBKOD9TDcwdaq6FfFPC2IJoaEY-SLY3EWZ8qh5GjY763JpEqVbJ3i3gqM/s1600/test0426a5.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1000" data-original-width="1600" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgndOjvfEKuA3kNmQDEjUkPcOLYhMaJWl8OjcNU_Q3X0wzCIHnVJzCVlphgYk24h3XbLIelvMORlxHu11lvArmBKOD9TDcwdaq6FfFPC2IJoaEY-SLY3EWZ8qh5GjY763JpEqVbJ3i3gqM/s640/test0426a5.jpg" width="640" /></a><br />
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<br />WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com2tag:blogger.com,1999:blog-4193169306787079445.post-17837541210351495712018-04-29T15:52:00.000-04:002018-05-18T10:11:56.476-04:00Indirect Ophthalmoscopy using a Raspberry Pi -- Part 1Periodically your ophthalmologist will want to perform a dilated retinal exam on you. He or she will put a drop in each eye to dilate the pupils, wait about twenty minutes and then use a lens and light to examine your retina. The retina is the light sensitive tissue on the inside of the eye. Generally this is a screening exam for, among other things, diabetic retinopathy. Retinopathy is a disease of the retina, and thus diabetic retinopathy is such a disease caused by diabetes.<br />
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These are important examinations but are unpopular among patients for a few reasons. They require extra time for the eye drops to take effect, and then that effect lasts for several hours. During that time the eyes are particularly sensitive to light, and the vision is often blurry making it difficult to drive and to read.</div>
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My brother is an ophthalmologist and he pointed out to me an article written by a couple of doctors at the University of Illinois (<a href="https://www.hindawi.com/journals/joph/2017/4526243/" target="_blank">here</a>) in which they described building a non-mydriatic fundus camera. Mydriasis is the dilation of the pupil and in this case fundus refers to the inside back of the eye. These instruments are available but they are extremely expensive. The interesting thing about this article is that it describes building such a camera using a Raspberry Pi with a Pi Camera.</div>
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The key idea in the article is that instead of using a chemical to dilate the patient's pupil, the patient is placed in a darkened room and the pupil is allowed to dilate naturally. The problem with this approach is that in the dark the examiner cannot see to focus the camera, and because the dimensions involved are so small, the focus is critical. However, the article describes using a combination infrared and white LEDs for illumination. Generally, electronic cameras are sensitive to infrared light but human eyes are not. Thus, the examiner illuminates the eye in infrared light and viewing the image from the camera is able to focus, and then flashes the white LED to take the picture. The white light produces an image with good color rendition, an important factor in performing the exam, but the flash is so fast that the patient's pupil doesn't react until after the picture is taken.</div>
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A significant advantage of an inexpensive fundus camera is that the retina could be imaged in settings other than a doctor's office. Clinics, schools and so forth could capture the images and they could then be reviewed by a retina specialist at a later time. My brother suggested that we try to build one of these camera systems, and therein lies a tale.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9l8Pn_y5jLRbia5rOSgMc_XeePgeaTrq9zzHyzm_i7kRu9PW82u8DDK2S4ZLGAsdiaxBpU87SCdsQaAxev40LQ5imEcIPmQwPpdYNILw08uBjH8W-p_lSuEjDOYJMcKa7eynbopg_WGY/s1600/2WayMirror.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9l8Pn_y5jLRbia5rOSgMc_XeePgeaTrq9zzHyzm_i7kRu9PW82u8DDK2S4ZLGAsdiaxBpU87SCdsQaAxev40LQ5imEcIPmQwPpdYNILw08uBjH8W-p_lSuEjDOYJMcKa7eynbopg_WGY/s320/2WayMirror.JPG" width="320" /></a>One of the trickiest parts of taking a picture of the retina is the fact that it must be taken through the pupil. Even when dilated that is an opening of only a very few millimeters. Through this tiny opening light must be shone to illuminate the retina as well as the picture taken. That means that the light must be very close to the main axis of the camera lens. The University of Illinois group used a prototype of a tiny LED made by a Japanese company that can emit both IR light as well as white light. With the help of a Japanese friend of mine we undertook to obtain a few of these prototypes. Pending their arrival we did some experiments using a group of conventional LEDs and a partially silvered mirror (left). The idea was that the camera would take a picture of the eye as reflected in the front of the mirror while the eye was illuminated by LEDs behind the mirror. Thus the LEDs could be made precisely collinear with the camera.</div>
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Now, the way the retina is usually examined is that the ophthalmologist uses a 20D hand lens that he or she holds close to the patient's eye. At the same time the doctor observes the image in the hand lens using a light source and another magnifying lens that is often worn as a headlamp. Getting a good view is tricky business because it involves moving the two lenses and light such that the image is appropriately magnified, while maintaining an adequate field of view as well as having the image in focus. This is complicated by the fact that if the patient is near sighted or far sighted the correct position of the lenses changes. With practice doctors develop a good facility for this. As you might imagine, however, doing this with a camera, screen and light as well as the 20D condensing lens can be a challenge.</div>
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We built such a device and experimented around with it. We were completely unsuccessful at getting a clear view of the retina in IR light and thus could not get a good picture. Try as we might there were just too many variables, including the number of LEDs, the focus of the lens on the Pi Camera, the distances, the size of the device, etc., etc.</div>
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Around this time the Japanese LEDs arrived. We replaced the conventional LEDs that we had been using. These new LEDs were SMT (surface mount technology) and so had tiny solder pads and presented their own challenges but we were able to get them closer to collinear with the camera and so eliminated the partially silvered mirror. Nothing else changed, including our results.</div>
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We thought it might make sense to go back to first principles so we started from scratch. This time we built an optical bench that we could use to do more precise experimentation. I'll show you that in my next post.</div>
WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-25866624354391546152017-09-24T12:44:00.003-04:002017-09-24T12:44:52.409-04:00Rolling Ball SculptureLike so many things, and I suppose life in general, if I could do it over again I would be much smarter about how to do my first rolling ball sculpture. On-line there are many fine examples and much excellent documentation about how to make these things. Rather than attempt to duplicate the documentation that is already out there I thought I would show a few pictures and mention a few things that I figured out along the way.<br />
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For those of you who don't care how these things are made but want to see what it looks like when it's done, here is a link to the <a href="https://youtu.be/ilkbSHCLL44" target="_blank">YouTube video</a>.<br />
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I took two approaches to this. First, there were some features that I had seen in other people's sculptures that I wanted to duplicate and some ideas of my own that I wanted to try out. I made prototypes of these.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDW4CnW8is7Y1YqvF3hpsn6bAE4aTHkRVkpgIGmISVtFAO2YK2gI4z0H2IoQdrzo3IXzltzZC5yMrWmPnn5x347_ujS0_hnwgdCVtbTcZmQLpj79t2rYcoW6lWWJ9fKM7uZ6kec2jDq8M/s1600/P1000021.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDW4CnW8is7Y1YqvF3hpsn6bAE4aTHkRVkpgIGmISVtFAO2YK2gI4z0H2IoQdrzo3IXzltzZC5yMrWmPnn5x347_ujS0_hnwgdCVtbTcZmQLpj79t2rYcoW6lWWJ9fKM7uZ6kec2jDq8M/s400/P1000021.JPG" width="300" /></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5qUgwTjCWWpXps6quQVo3VlmleMjC7XN2a4dRP-iH-gUXByu5X5QuM7WeicMRRt_UoS31dG0WTW9S0RCVWw5Jo0cngcQqP0Xdi60peZ7hNmzLsS95258JuiShGLdCHAHsFDk7U0R9BNg/s1600/P1000020.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5qUgwTjCWWpXps6quQVo3VlmleMjC7XN2a4dRP-iH-gUXByu5X5QuM7WeicMRRt_UoS31dG0WTW9S0RCVWw5Jo0cngcQqP0Xdi60peZ7hNmzLsS95258JuiShGLdCHAHsFDk7U0R9BNg/s400/P1000020.JPG" width="300" /></a><br />
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I soon realized, however, that the performance of many of these features was dependent on the speed of the marble.<br />
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That led me to the second approach as to where to start. I figured that I would just follow the path of the marbles, adding and testing features as I went. That meant I had to decide how I would lift the marbles to the top of the sculpture.<br />
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I decided on a design that is analogous to Archimedes Screw for lifting water. I had seen a number of versions of this in YouTube videos and thought I understood how it worked until I tried to build it. Between the loading and unloading of the marbles and structure required to push them up the screw I kept getting confused as to the interaction of the screw mechanism that was turning and the rest of the structure that was not.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjaMaUQz3wJ-arDyxxXFEz6Syp3XO6E6hBKxm0odWGeS5sIrHkhqjEPjU4KvfSItCz1sKLXnUBRZfqdmbYGCTDR_172_MZmf5zkncqs8cg2IRpbEIatvsUUD7Az7CgROsHhQtisWiyvFQE/s1600/IMG_20170114_162825.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="900" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjaMaUQz3wJ-arDyxxXFEz6Syp3XO6E6hBKxm0odWGeS5sIrHkhqjEPjU4KvfSItCz1sKLXnUBRZfqdmbYGCTDR_172_MZmf5zkncqs8cg2IRpbEIatvsUUD7Az7CgROsHhQtisWiyvFQE/s640/IMG_20170114_162825.jpg" width="360" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixhu8GkBZd_GjGZnoUS8YnydIQr8aJGyUxsDYZWbCV5tk7dgZ-DEZRZlzz-1RQCHNdSOKm718FkL64QhzbV-Fbm8NOd4cGgpJ7kaGFkuQeVMxJXpssY5-7x-QeXzv6der6BqZPC3LwEu8/s1600/IMG_20170316_105121.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1600" data-original-width="900" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixhu8GkBZd_GjGZnoUS8YnydIQr8aJGyUxsDYZWbCV5tk7dgZ-DEZRZlzz-1RQCHNdSOKm718FkL64QhzbV-Fbm8NOd4cGgpJ7kaGFkuQeVMxJXpssY5-7x-QeXzv6der6BqZPC3LwEu8/s640/IMG_20170316_105121.jpg" width="360" /></a></div>
Here again I built a prototype. I had also read on-line that this type of lift worked best if it was kept to 24 inches or shorter, and I wanted mine to be almost twice that.<br />
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With the courage of the naive I plunged ahead figuring any problem the extra length caused could be solved by a bigger motor. I added a thrust bearing at the bottom of the screw (it's amazing what you can find on Amazon.)<br />
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It seemed to work fine with a few marbles and figured I had the design licked until I loaded it full of marbles. The motor I had was powerful enough but the problem was elsewhere. In this picture you can see the two vertical rods, one on either side of the screw. As the screw turns the marbles can't fit between those vertical rods and the central shaft of the screw and thus the marbles are pushed up hill.<br />
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It turns out that with a full load of marbles there was so much pressure on the vertical rods that they started to flex. Eventually a marble would get wedged between the rod and the screw. The motor kept turning and the marble would pop past the rod. The rod would snap back and marbles would go flying like corn in a popper.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgv0wzhL5zS0dA-oUa0NSXasmTp5KajIi-dbqMns0Je7hpX5uM75FH-qehXSk92SA8g-jK0mhmQgJR4yh3-MMmkjLZIxtvuTAvuG4MkxmfBxlLHXUu6lEWLoO2FGBy4VZei0zQjCXBo4Dc/s1600/IMG_1886.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgv0wzhL5zS0dA-oUa0NSXasmTp5KajIi-dbqMns0Je7hpX5uM75FH-qehXSk92SA8g-jK0mhmQgJR4yh3-MMmkjLZIxtvuTAvuG4MkxmfBxlLHXUu6lEWLoO2FGBy4VZei0zQjCXBo4Dc/s400/IMG_1886.JPG" width="300" /></a>I despaired having to replace those rods with something heavier. As luck would have it, my sister Monica and her husband Jim were visiting and I was whining to them about the problem. They suggested just putting a wrap of wire around the outside of the rods...problem solved.<br />
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Once I had the lift working I just started adding things from the top to the bottom, factoring in the features I wanted and experimenting with fit, marble speed, aesthetics and so forth.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWRlUic-s0_XQzBPeiwmCK2g8arEYMxFuhPcVu91eec9TtnOHeoe77dw1yAA2UfAokJMV3EQnXIi6tsLTqpR59LQ6Ze-DUkyf33KHxfm0AT772TliSMBDoxdBntLAPTtsNDjMHiErjpic/s1600/IMG_1879.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWRlUic-s0_XQzBPeiwmCK2g8arEYMxFuhPcVu91eec9TtnOHeoe77dw1yAA2UfAokJMV3EQnXIi6tsLTqpR59LQ6Ze-DUkyf33KHxfm0AT772TliSMBDoxdBntLAPTtsNDjMHiErjpic/s400/IMG_1879.JPG" width="400" /></a>I learned a few things here as well. Maintaining the proper separation between the rails is obviously very important. Some people have some small, elegant pieces to do this, and my plan was to do something similar. Try as I might, though, I couldn't design a clamp that held the separator piece in place, held the tracks at the proper separation, and still gave me enough room to get in there and solder everything together. To the right is a picture of one of my earlier (and uglier) efforts.<br />
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Then my friend Jim and I hit on just using rings. They were much easier to clamp and indeed in many circumstances I could just put the track upside down on the bench and the ring would hang in the right position for soldering. I had originally planned to cut off the part of the ring that is above the rails after they were soldered in place but I decided I like the look of them and so left them.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjv6kWmBhMW8m2vXOqtvERx2rYufNUQjVOqbhIQp7aVQGN4l6ueWAXo2pO9tYKp9G_zyMhzD5FSMXGx-iiigQLiRSbEex8eHZpbxqPaBxDoXwXc-cqqLQY6FQT4blTSsMIVMMHa_jAg2D8/s1600/P1000015.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjv6kWmBhMW8m2vXOqtvERx2rYufNUQjVOqbhIQp7aVQGN4l6ueWAXo2pO9tYKp9G_zyMhzD5FSMXGx-iiigQLiRSbEex8eHZpbxqPaBxDoXwXc-cqqLQY6FQT4blTSsMIVMMHa_jAg2D8/s320/P1000015.JPG" width="320" /></a>I also realized that if the rails were close enough together then the marble would not extend below below the rails as it rolled along, and thus I could use straight wire to, for instance, connect the loops of a spiral so this one turned out nicer than the one shown above.<br />
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That brings up something else I wanted to mention. When making curved track, there are a couple of ways it can be designed. The first I call "safe" track. In this approach a marble is held on track both dynamically and statically. By that I mean that when a marble is rolling around a curve two of the forces working on it are gravity and momentum. The gravity is, of course, pulling it downward. Its momentum, sometimes called centrifugal force, tries to keep it going in whatever direction it is already going. Thus, curved tracks are usually banked to keep the marble from flying off. For a typical curve, the two rails can be configured such that the outside rail is just above the center of the marble and the inside rail is just inside of the center of the marble. Thus no matter how fast or how slow the marble is moving it won't fall off the track. In the case of a loop, so the track is actually above the marble in order for the track to be "safe" a third rail is required, usually opposite the other two, in case the momentum of the marble is not adequate to counteract gravity.<br />
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"Unsafe" track, on the other hand, is arranged so that for a given speed the combination of the rails, gravity, and momentum will support the marble. This type of track can be much more tricky to implement because you need to know how fast the marble will be going when it hits that section of track. In my opinion, the "unsafe" track is more fun to watch but it is most noticeable on loops.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1tnkHsg6mPmiOkxrSZo_oLY1AbxwKinsbJ6Esg9V8ItW1XfKrT9rfChFznWaF58SIXqVbiNhtC3nA4PI4Fd5k74xZZB9mjzv13CHzVV5dtyB75_yF6326cb9RliMlA2d8-5K5ZRSj1CY/s1600/IMG_1884.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="1200" data-original-width="1600" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1tnkHsg6mPmiOkxrSZo_oLY1AbxwKinsbJ6Esg9V8ItW1XfKrT9rfChFznWaF58SIXqVbiNhtC3nA4PI4Fd5k74xZZB9mjzv13CHzVV5dtyB75_yF6326cb9RliMlA2d8-5K5ZRSj1CY/s400/IMG_1884.JPG" width="400" /></a></div>
There is one more thing I think is worth mentioning. As my sculpture neared completion I found that sometimes some features would work and sometimes not. Marbles would fall out of loops, or would stop on flat sections of track. Other times they would work perfectly. I came to realize that this was due to vibrations in the sculpture. Sometimes the period of those vibrations was such that they would absorb enough energy from the rolling marble that it wouldn't have enough speed to complete the feature. To solve this problem I had to add a bunch of braces just to stiffen everything. I know this picture is kind of confusing to look at but if you look closely you can see a couple of these braces in the foreground.<br />
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Ok, that's about it. There are some much more well executed and much more beautiful sculptures on-line. As I said at the outset, my second one would be much nicer, but I had tons of fun building this one, and if you're planning to make one yourself I hope the tips are useful.<br />
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Here, again, is a link to the <a href="https://youtu.be/ilkbSHCLL44" target="_blank">YouTube video</a> of the sculpture in action. Oh, one final thing. I realize why all the videos you see are set to music. It's because these things are as noisy as a can factory. My dog hides under the bed every time I turn it on.<br />
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<br />WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com1tag:blogger.com,1999:blog-4193169306787079445.post-45658397715319638142016-11-08T07:08:00.000-05:002016-11-08T07:08:04.144-05:00Music & Me -- Part 5<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9fmkbIoygkaGAbxMk_8EyMyT1kRYxT9o770EQcCO9e7gs07BUpmNx9_1D353BrZeSLLumMX_-VJPXAtJRPHR0UqJJImb4uI-FYK3_8kN8nHAMhegrupm1iiMXMXCO_hTFhvGea3Zqmcc/s1600/IMG_0450.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9fmkbIoygkaGAbxMk_8EyMyT1kRYxT9o770EQcCO9e7gs07BUpmNx9_1D353BrZeSLLumMX_-VJPXAtJRPHR0UqJJImb4uI-FYK3_8kN8nHAMhegrupm1iiMXMXCO_hTFhvGea3Zqmcc/s400/IMG_0450.JPG" width="400" /></a>Had a great time at the Orlando Maker Faire October 22nd and 23rd. The pipe organ proved to be very popular with several hundred people stopping by to ask about how it worked and how it was made.<br />
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It was especially popular with the kids.<br />
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Also, I was interviewed by Caleb Kraft of Make Magazine. <a href="http://makezine.com/2016/11/04/listen-to-the-eerie-music-of-this-handmade-midi-pipe-organ/" target="_blank">Here is a link to the interview</a>.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEisXVJptcZLPkQ8ip4XJRmMNLmQVlRvnJeQToFMsO8ineupHPS8ux6J9mLRL1cIAY1s4zn2WvayUq5jUCw4K7hGj9h1xIiZYTw-kK3rG52P9kwc1xFJUQXy9qJ7kjoO3JGf6i-kh-cMEvs/s1600/IMG_0469.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEisXVJptcZLPkQ8ip4XJRmMNLmQVlRvnJeQToFMsO8ineupHPS8ux6J9mLRL1cIAY1s4zn2WvayUq5jUCw4K7hGj9h1xIiZYTw-kK3rG52P9kwc1xFJUQXy9qJ7kjoO3JGf6i-kh-cMEvs/s400/IMG_0469.JPG" width="400" /></a></div>
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My friend Jim, who has been helping me, and our wives came along. Here you can see the Maker of Merit award that we got.<br />
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Finally, after the interview Caleb Kraft suggested that adding LEDs to the organ indicating the note that was playing would make it more interesting to watch. I did that and <a href="https://www.youtube.com/watch?v=mX-LpXxwWxY" target="_blank">here is a YouTube video showing the newly added LEDs</a>.WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com11tag:blogger.com,1999:blog-4193169306787079445.post-54977118481888658732016-10-10T10:37:00.003-04:002016-10-10T10:38:43.867-04:00Orlando Maker Faire<br />
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I will be displaying my Player Pipe Organ at the Orlando Maker Faire on October 22nd and 23rd. If you're in the area please stop by. Or, better yet, volunteer at the Maker Faire (and get in for free.)<br />
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<span style="margin-left: 1em; margin-right: 1em;"><a href="http://makerfaireorlando.com/" target="_blank">Orlando Maker Faire</a><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhc2qLEbR6iRMYaJeV9Xe357E_zlTBBRj1mC0HOS9USuWf7suGPhZNb377C6QocZq-7obCuvxg9BJrpuL-3-8njU0p-aGaFyrmRLTnMC2ka1VXIHGjd7wA5rEBepZOQhu4JlJXqkHWeERw/s400/Orlando_MF_Logo_twitter.png" width="400" /></span></div>
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<br />WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com5tag:blogger.com,1999:blog-4193169306787079445.post-227762308382681852016-04-03T20:51:00.000-04:002016-04-07T23:46:03.737-04:00Music & Me Part 4 -- Version 1.0 is complete<br />
It's finished, completed, accomplished, discharged, ended, concluded, done.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiz3xtFum4W-_J6pEAKZR51lQ0aWLiBtX20b0yjUft2Oui1cnf98W5M8UDUIxmy3Ih86NqhgxSeCFjbJNdIclQEuahcr070BdRNbbhOQ_Jj4Turv7eViZ21-066AwdLVMvJYGHXUv2aUM0/s1600/IMG_1130.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiz3xtFum4W-_J6pEAKZR51lQ0aWLiBtX20b0yjUft2Oui1cnf98W5M8UDUIxmy3Ih86NqhgxSeCFjbJNdIclQEuahcr070BdRNbbhOQ_Jj4Turv7eViZ21-066AwdLVMvJYGHXUv2aUM0/s400/IMG_1130.JPG" width="400" /></a>For those of you who have not been following along at home, please check out the first three installments of this project. Since my last post I finished the plumbing, again with the help of my friend Jim. You may remember from earlier posts that the wind chest has valves that control the flow of air to the organ pipes. Here you can see them with white leaf springs holding them closed. The air then needs to actually get to the pipes, which sit over the holes some of which you can see in the top of the picture.<br />
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This was accomplished using pvc plumbing pieces as shown here. The underside of the wind chest is on the left and the organ pipes sit atop the plumbing on the right.</div>
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Here is my source of air or as the organ folks say, wind. I couldn't afford a real organ blower so I went with the Shop-Vac solution. I built this box to accomplish two things. First, one could hardly hear the organ over the roar of the Shop-Vac so I needed to do something about the noise. Second, the higher the pressure in the organ the higher the pitch of the pipes. Therefore, a pressure regulator is needed to limit the changes in pressure that occur as different numbers of pipes are playing at one time. The lower box contains the Shop-Vac and muffles its noise. The upper box further muffles the noise and regulates the pressure.</div>
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Let's start with the pressure regulator first. My friend Jim used to have an HVAC (Heating, Ventilating, and Air Conditioning) business and he showed me how they regulate pressure in those systems. You can see an example on the left side of the top box. There is a door, hinged at the top. Sticking out of the door is a rod, and on the rod is a weight. When the system is running, most of the time it produces more air than the organ needs. The excess air shoves the door open and escapes. If the pressure starts to drop, as it does when more pipes are playing, the lower pressure can't hold the door open as much so the door closes a little and that boosts the pressure. The pressure can be regulated by sliding the weight in or out on the rod.</div>
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After getting the organ working, Jim and I went through endless sessions of tuning the forty-two pipes. We used an app called Pano Tuner, a screen shot of which is shown here. The app worked beautifully, the organ somewhat less so. After much trial and error we learned that the pipes were so close together that their sound was impacted by the pipes around them. Also, at first we were playing around with the pressure and every time we changed it we had to re-tune all the pipes. Even after we chose a final setting for that, though, we would tune the organ in the morning and when we came back in the afternoon the pipes would all be sharp or flat. We figured it may have to do with temperature and humidity. I live in Florida and the organ is in my garage so those parameters can vary quite a bit but I haven't brought it indoors yet to test that theory.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxt0ASPA4iCnY9Blga8ZuUL1FXkqhdweFSnLBqLQJTMoLXq1tQpSWcdxOXHxTdtboYEd02-r-cFnyXUcT1LZV8TKK7_nq-mcdxl3UVpluhxNd_d4XlGDwHInOrFsq7Ch0I39Kq4Bikcy8/s1600/IMG_1212.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxt0ASPA4iCnY9Blga8ZuUL1FXkqhdweFSnLBqLQJTMoLXq1tQpSWcdxOXHxTdtboYEd02-r-cFnyXUcT1LZV8TKK7_nq-mcdxl3UVpluhxNd_d4XlGDwHInOrFsq7Ch0I39Kq4Bikcy8/s320/IMG_1212.JPG" width="320" /></a>And that's it. Here are me (on the right) and Jim relieved that version 1.0 is complete. Now, those of you who have stuck with me this far get either a reward or punishment depending on your perspective. Here is a link to a <a href="https://youtu.be/uC-jZ3AJCgc" target="_blank">YouTube video</a> of the organ in action. Thanks for reading my blog.</div>
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And thanks once again to Matthias Wandel at <a href="http://woodgears.ca/" target="_blank">woodgears.ca</a> and Raphi Giangiulio at <a href="http://rwgiangiulio.com/" target="_blank">rwgiangiulio.com</a>. I stand on the shoulders of giants.</div>
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<br />WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com3tag:blogger.com,1999:blog-4193169306787079445.post-85189076556447403302016-01-27T13:48:00.000-05:002016-01-27T13:48:11.449-05:00Music and Me Part 3Around two years ago I wrote about building a pipe organ in a post called Music and me continued. At the end of that post I said that the number of solenoids that I would need would cost quite a bit of money and I wasn't sure when I would get back to it (i.e. I am too cheap to spend that kind of money on the project.)<br />
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Well, my friend Jim from across the street came over just before Christmas and I was showing him the pipes that I had made and he asked what the next step was in the project. I said that solenoids were too expensive to take it any further and by way of illustration I called up the Electronic Goldmine website (<a href="http://www.goldmine-elec-products.com/" target="_blank">http://www.goldmine-elec-products.com/</a>) and what to my wondering eyes did appear but solenoids on sale for $5 each. I quickly penned a letter to Santa and there, under the tree on Christmas morning were 42 solenoids. I was back in motion once again.<br />
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Jim and I spent hours working on designs for the configuration for the solenoids and eventually hit on something that we thought would work, and here it is in the flesh.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXzsjHt2YrOkVl3Ajq-RELIlb76hKVnbmRqwn5I-oVKpbXx7xlcfF4TcSxppQ6OhfD-YOpkdcBJwZpzMgHAjncSlhpACmNtYorlv4C0uydiIs2sp80nuP5Vlc7ZsoQHa9rVGRoc-VLmsg/s1600/IMG_1129.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXzsjHt2YrOkVl3Ajq-RELIlb76hKVnbmRqwn5I-oVKpbXx7xlcfF4TcSxppQ6OhfD-YOpkdcBJwZpzMgHAjncSlhpACmNtYorlv4C0uydiIs2sp80nuP5Vlc7ZsoQHa9rVGRoc-VLmsg/s400/IMG_1129.JPG" width="400" /></a></div>
In the lower part of the picture is the "wind chest" that I mentioned in my last post on this topic. This is a design that I pretty much just stole from Matthias Wandel from his <a href="http://woodgears.ca/" target="_blank">woodgears.ca</a> website. For springs I used hacksaw blades because they are made of spring steel. You can see that there are two rows of valves with the (mostly) white hacksaw blades pressing them down (closed). Above the wind chest you can see that there are two aluminum angles, the bottom one is populated with solenoids, the top one not yet.<br />
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Running down from the solenoids you might be able to spot thin wires attached to the valves. When the solenoid is powered it pulls on the wire and opens the valve.<br />
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So far so good. How do I play music? I mentioned in an earlier post that I planned to use MIDI (Musical Instrument Digital Interface). This is a standard that is more than 30 years old. It is used to control digital musical instruments like synthesizers, to manage stage lighting and pyrotechnics that are coordinated with music and so on. There are many thousands of songs in MIDI format available for free online. These are not sound files, though. They are instructions on what notes to play, when, for how long, and at what volume. Here is an example of some lines from a MIDI file converted to text.<br />
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<span style="font-family: Courier New, Courier, monospace;"> 4: 1: 0 |On Note<span class="Apple-tab-span" style="white-space: pre;"> </span> | chan= 3 | pitch=C#2<span class="Apple-tab-span" style="white-space: pre;"> </span> | vol=66</span><br />
<span class="Apple-tab-span" style="font-family: 'Courier New', Courier, monospace; white-space: pre;"> </span><span style="font-family: 'Courier New', Courier, monospace;"> |On Note</span><span class="Apple-tab-span" style="font-family: 'Courier New', Courier, monospace; white-space: pre;"> </span><span style="font-family: 'Courier New', Courier, monospace;"> | chan= 3 | pitch=C#1</span><span class="Apple-tab-span" style="font-family: 'Courier New', Courier, monospace; white-space: pre;"> </span><span style="font-family: 'Courier New', Courier, monospace;"> | vol=64</span><br />
<span class="Apple-tab-span" style="font-family: 'Courier New', Courier, monospace; white-space: pre;"> </span><span style="font-family: 'Courier New', Courier, monospace;"> 24 |On Note</span><span class="Apple-tab-span" style="font-family: 'Courier New', Courier, monospace; white-space: pre;"> </span><span style="font-family: 'Courier New', Courier, monospace;"> | chan= 3 | pitch=F#2</span><span class="Apple-tab-span" style="font-family: 'Courier New', Courier, monospace; white-space: pre;"> </span><span style="font-family: 'Courier New', Courier, monospace;"> | vol=52</span><br />
<span class="Apple-tab-span" style="font-family: 'Courier New', Courier, monospace; white-space: pre;"> </span><span style="font-family: 'Courier New', Courier, monospace;"> 43 |(Off) Note | chan= 3 | pitch=f#2</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> 48 |On Note<span class="Apple-tab-span" style="white-space: pre;"> </span> | chan= 3 | pitch=G#2<span class="Apple-tab-span" style="white-space: pre;"> </span> | vol=56</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> 61 |(Off) Note | chan= 3 | pitch=g#2</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> 72 |On Note<span class="Apple-tab-span" style="white-space: pre;"> </span> | chan= 3 | pitch=E 3<span class="Apple-tab-span" style="white-space: pre;"> </span> | vol=88</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> |On Note<span class="Apple-tab-span" style="white-space: pre;"> </span> | chan= 3 | pitch=B 2<span class="Apple-tab-span" style="white-space: pre;"> </span> | vol=76</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> |On Note<span class="Apple-tab-span" style="white-space: pre;"> </span> | chan= 3 | pitch=F#2<span class="Apple-tab-span" style="white-space: pre;"> </span> | vol=76</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> |On Note<span class="Apple-tab-span" style="white-space: pre;"> </span> | chan= 3 | pitch=G#2<span class="Apple-tab-span" style="white-space: pre;"> </span> | vol=68</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> 90 |(Off) Note | chan= 3 | pitch=g#2</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> 91 |(Off) Note | chan= 3 | pitch=b 2</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> 94 |(Off) Note | chan= 3 | pitch=c#2</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> 95 |(Off) Note | chan= 3 | pitch=e 3</span><br />
<span style="font-family: Courier New, Courier, monospace;"><span class="Apple-tab-span" style="white-space: pre;"> </span> |(Off) Note | chan= 3 | pitch=f#2</span><br />
<span style="font-family: Courier New, Courier, monospace;"> 2: 8 |(Off) Note | chan= 3 | pitch=c#1</span><br />
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The numbers on the left are timing. Then comes the instruction. The channel is the instrument, then the note, and finally the volume. This particular MIDI file breaks each beat into 96 increments. So, for instance, the first line says "at the beginning of the first beat of the fourth measure, for instrument number 3, start playing C# in the second octave at a volume of 66". The next line says "at the same time start playing C# in the first octave". Then after 24/96ths of a beat (or actually 25/96ths of a beat because the counting starts at 0 rather than 1) start playing F# in the second octave. Then 19/96ths (43-24=19) of a beat later turn of F# in the second octave. And so on, and so on.<br />
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I had an Arduino Due microcontroller and hooked up an SD card reader to it and put a MIDI file on the SD card. <br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5sDeUA2hywTL_lbSH1YXqaJk1Hze5QEOtSomyWbkRdFnRnzRVRWwFnKZDmeGZTUbaovK8cAEXpp0NYoU8zqFFgHlrslaycq_1f9Dwdm0d9ER25qGjT0_QMT9XYZduiATErEEldGB2wvE/s1600/IMG_1136.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5sDeUA2hywTL_lbSH1YXqaJk1Hze5QEOtSomyWbkRdFnRnzRVRWwFnKZDmeGZTUbaovK8cAEXpp0NYoU8zqFFgHlrslaycq_1f9Dwdm0d9ER25qGjT0_QMT9XYZduiATErEEldGB2wvE/s400/IMG_1136.JPG" width="300" /></a></div>
Here is the Arduino. It has 53 output pins. Under program control it can turn each of these on or off. I wrote a program on the Arduino that assigns each note to a pin. Then it reads the file and turns the pins on and off with the correct timing. Since I only have 42 notes on the organ I only need 42 pins. These pins can only supply a tiny amount of electricity, however, not nearly enough to trigger a solenoid.<br />
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My sister Monica and her husband Jim happened to be visiting, and she and he and I built this board. <br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4KucAkKZICItQTLpV9HLO-LZPz6BNJD5Fiz7YuujLhxN5X69C_pdQcoRli0yCnZ_zMGEitKXQDzenM8gSxkdIaVf4BH0yl2bh-93LDZTNtQVQmFuFtN1vhETqoFVsyNYYIcO2UON4MAA/s1600/IMG_1127.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4KucAkKZICItQTLpV9HLO-LZPz6BNJD5Fiz7YuujLhxN5X69C_pdQcoRli0yCnZ_zMGEitKXQDzenM8gSxkdIaVf4BH0yl2bh-93LDZTNtQVQmFuFtN1vhETqoFVsyNYYIcO2UON4MAA/s400/IMG_1127.JPG" width="400" /></a></div>
The main components are 42 transistors. These work like electronic switches. The tiny amount of electricity from the Arduino can turn on a transistor, and a transistor can switch enough electricity to trigger a solenoid.<br />
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I still have to wire all this stuff together but I'm pretty confident that it will work<br />
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And what about all those pipes, you might ask. Not tons of progress on that front, with one exception. Again, I have been using the information provided by Raphi Giangiulio's YouTube videos on <a href="http://www.youtube.com/watch?v=-mibK_Dp-ZY&feature=c4-overview-vl&list=PL5D21F4F0A098A233" target="_blank">how to make wooden organ pipes</a>.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzcpthLo1vwB1YJ3-8BxRv18XfYQTsrm-GcRTj0hatotGhRYhSU4YayoJBAgHUA_MYNF9ItvmFC1-gVetGmTubOJn67R1acXP21LZkp2U41f_OZOlHHizoIM6_HBfpoE_x9asrVRLo9o0/s1600/IMG_1132.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzcpthLo1vwB1YJ3-8BxRv18XfYQTsrm-GcRTj0hatotGhRYhSU4YayoJBAgHUA_MYNF9ItvmFC1-gVetGmTubOJn67R1acXP21LZkp2U41f_OZOlHHizoIM6_HBfpoE_x9asrVRLo9o0/s400/IMG_1132.JPG" width="300" /></a>In looking at his specifications there was something that didn't make sense to me. As the pitch gets lower the pipes get bigger until we get below C below middle C. Then they are significantly smaller. I didn't understand that so I sent an email to Raphi and he generously responded and explained that Bourdan pipes are stoppered. That means there is an airtight stopper put into the pipe and that lowers the frequency. It's counter-intuitive but it works. Here are a series of five pipes in order of frequency with the lowest on the left. <br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHSfesV7ZQVX-e-DlViJISkq0vjit8ck14Lco9AMbT4iIBgw6amq5gFNyuFLgoaZgNKRN1otC-NZlbGfj6CshD2ukml56AYBTXnOJmfr2hhO2tH-yk-gUR-Qw-l2rUJcuEduKH2tb-LOM/s1600/IMG_1134.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHSfesV7ZQVX-e-DlViJISkq0vjit8ck14Lco9AMbT4iIBgw6amq5gFNyuFLgoaZgNKRN1otC-NZlbGfj6CshD2ukml56AYBTXnOJmfr2hhO2tH-yk-gUR-Qw-l2rUJcuEduKH2tb-LOM/s400/IMG_1134.JPG" width="300" /></a><br />
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And here is a shot of a couple of stoppers.<br />
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I have only 18 pipes of the 42 pipes made, and so I am not nearly finished with the project but I am re-invigorated. I'll keep you up-to-date.<br />
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WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com17tag:blogger.com,1999:blog-4193169306787079445.post-83568513491495401802015-10-15T14:50:00.001-04:002015-10-15T14:50:45.583-04:00Matching headboardRegular readers might remember that sometime back I built a bench for the foot of our bed. At the time I mentioned that we had a queen size mattress but were thinking of upgrading to a king size. The issue was that Peg likes a firmer mattress and I like a softer one. I thought about one of those Sleep Number beds where each side is adjustable as to firmness. I priced them, however, and realized that it would be cheaper to buy a car and sleep in there. Then, as luck would have it we were up visiting Abigail in Washington D.C. We stayed in a Marriott hotel and we both liked the bed. I looked for a tag on the mattress. It was a Serta but didn't have a model name or number. Peg looked on the Serta website and they said that if you stayed in a hotel and liked the mattress you could call Serta and order the same model direct from them. So I did. <br />
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Now, however, the pressure was on. I had to actaully make the headboard to match the bench that I had been talking about. I had enough cherry left over, and enough caning so I did it, and here are the pictures to show you.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHM4XAiKsSbE0vfpfpQ4hTiaztVw7Iq-BP4xH-dmy_pct_n91-cgcuSSImbm8RqnzYinxPnqxBOE1UaIEUtJHmh8bC-BjEuemgPYZg-Lo4vSkPEPmb2Fb6w4eRhE34m57M2Vq2yvbbW_M/s1600/IMG_1042.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHM4XAiKsSbE0vfpfpQ4hTiaztVw7Iq-BP4xH-dmy_pct_n91-cgcuSSImbm8RqnzYinxPnqxBOE1UaIEUtJHmh8bC-BjEuemgPYZg-Lo4vSkPEPmb2Fb6w4eRhE34m57M2Vq2yvbbW_M/s320/IMG_1042.JPG" width="320" /></a><br />
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I didn't have any 8/4 cherry so I made the posts by doubling the 4/4. These are the posts with mortices for the lower rail.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTgqK3rbpXDeG02kAB1wlxeFq4IIr8zuYmKyQqWsTyxw1o85TTizq3pEcYcO_1ul7Djw96X92hw9u2Bi5lWEoNSO2k1_6DP03WaduDCYooOQCmQ_hZ-hq4k-iysonjKPRluMwAwJT1r2c/s1600/IMG_1045.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTgqK3rbpXDeG02kAB1wlxeFq4IIr8zuYmKyQqWsTyxw1o85TTizq3pEcYcO_1ul7Djw96X92hw9u2Bi5lWEoNSO2k1_6DP03WaduDCYooOQCmQ_hZ-hq4k-iysonjKPRluMwAwJT1r2c/s320/IMG_1045.JPG" width="320" /></a></div>
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I cut one of the two 4/4 pieces shorter than the other giving me a way to overlap the upper rail. Here you can see one of the completed posts with a groove cut for one of the panels. You can also see the three stiles with their tenons and grooves cut.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3qdyh-O_LrKxNwSjFPwQztvZ1Oojh4oJ6QFL8UwXGgKygnEaOhZCa49nm4lH4NBibER2-HMjMIUitEr59GAXYztONmclQEwMzJP5IR6Jki02hThkDsTuAledrDqjRWrZIQO2iOWQOi-w/s1600/IMG_1046.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3qdyh-O_LrKxNwSjFPwQztvZ1Oojh4oJ6QFL8UwXGgKygnEaOhZCa49nm4lH4NBibER2-HMjMIUitEr59GAXYztONmclQEwMzJP5IR6Jki02hThkDsTuAledrDqjRWrZIQO2iOWQOi-w/s320/IMG_1046.JPG" width="320" /></a><br />
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Here's how I made the panels. I used half inch plywood. I glued the caning to one side and cut rabbets along the edges of the other side to fit into the grooves.<br />
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Here is the lower rail with tenons and groove cut.<br />
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And here you can see one of the mortices in the lower rail, cut to accept the tenon on the stile.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWGd5xNcZApd7_XC5ZnWMFXxSlX5CYGxD-E-RQxVqgohAfDxuWdVHnLBP1WpAYeiouL3l8GozA5vGQKzbKP3uZjwuE1cKCSdQ7_qqSsxFE7y8swhOXggboWq6O85NnK0Rw5TgRNVFs3eo/s1600/IMG_1050.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgWGd5xNcZApd7_XC5ZnWMFXxSlX5CYGxD-E-RQxVqgohAfDxuWdVHnLBP1WpAYeiouL3l8GozA5vGQKzbKP3uZjwuE1cKCSdQ7_qqSsxFE7y8swhOXggboWq6O85NnK0Rw5TgRNVFs3eo/s320/IMG_1050.JPG" width="320" /></a><br />
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Here are most of the pieces, ready to assemble.<br />
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And now the posts, lower rail, and stiles are glued together and ready for the panels to be inserted.<br />
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As no good deed goes unpunished I imposed on my friend Jim (who helped me with the Historic Spanish Point benches) to help me glue on the top rail. This glue-up was particularly exciting because we had to get the tenons on the three stiles into the three mortices, while at the same time getting the top rail aligned exactlly with the posts all before the glue dried. You can never have too many hands or too many clamps.<br />
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Next I cut grooves to fasten the header to the top rail using biscuits. To the uninitiated, buscuits are oval shaped pieces of compressed wood. When glue is applied to the grooves and the biscuit inserted, it swells and that in combination with the glue hold the joint firmly.<br />
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Six coats of polyurethane later and it's ready to go.<br />
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Ta-Daa. The finished product, matching bench, and hotel mattress.WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-36783438843368253722015-10-05T13:56:00.000-04:002015-10-05T13:56:50.705-04:00Benches for Historic Spanish PointSome of you may recall that a while back I made a model of the HSP (<a href="http://historicspanishpoint.org/" target="_blank">Historic Spanish Point</a>) orange sorter. They wanted to use it for their outreach program to take it to schools, nursing homes, and that kind of thing.<br />
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HSP has beautiful grounds that are part of the land that had been owned by Bertha Honore Palmer, the wife of Potter Palmer who built the Palmer House Hotel in Chicago. Besides being popular for historical tours and the like, they have facilities for weddings and other such gatherings. They have a small chapel the stained glass windows of which were the inspiration for one of the stained glass lanterns that I blogged about some months back.<br />
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Well, in order to better support (no pun intended) the gatherings they host there, HSP asked me to make some benches. I asked, with some trepidation, what they wanted the benches to be like. The reason for my fear dates back 25 years or so. I was going to build a swing set/climbing platform etc. in our back yard for the kids to play on. I thought it would be a good opportunity for them to learn about the design and planning process for such project. We sat down and collected a bunch of ideas about what things they wanted to include, how many levels, how tall, how many swings and so forth. Then we drew pictures to scale from different angles of how it would look. Finally we built a small model to help work out the construction details. They agreed that that it was just what they wanted.<br />
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Then I went to work. It took me a few weeks of weekends but finally it was done. I hung the swings, fastened the ladders and climbing ropes, checked to make sure there were no rough spots or slivers, and then invited the kids out to try it. They came running out and as they got close they stopped dead in their tracks. They said, "Where's the slide?" I asked what slide they were talking about. They said they thought there was going to be a slide. I took them back in the house and we reviewed the list of desired features we had developed at the start of the project -- no slide. I showed them the drawings. Then we looked at the model. I pointed out that there was no slide on either of those. They allowed as how that while that was true it should have been obvious that a structure like this should have a slide.<br />
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Fade out 25 years ago, fade in present day. Scarred as I am from that episode I always nervous when someone wants something built but don't have too firm and idea as to what exactly it should be.<br />
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In this case my fears were completely unfounded. Kara at HSP had found exactly what she was looking for on the web at <a href="http://www.thehappierhomemaker.com/2013/10/rustic-15-dollar-bench/" target="_blank">http://www.thehappierhomemaker.com/2013/10/rustic-15-dollar-bench/</a><br />
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What's more, the website included a dimensioned drawing and, much to my surprise the material costs really were around $15.<br />
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Kara brought the HSP truck and she and I went to Lowes and bought all the stuff.<br />
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I went into production line mode and cut all the pieces.</div>
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Mercifully, my friend Jim from across the street stopped by to see what was going on and volunteered to pitch in. We worked together over a number of days, improving our efficiency with each bench we completed.<br />
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Here are the first nine.<br />
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And here are the last sixteen. Kara seems pleased with them, and if she's happy, I'm happy. Thanks again to Jim for all his help, and thanks to <a href="http://thehappierhomemaker.com/" target="_blank">thehappierhomemaker.com</a> for a solid design.</div>
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<br />WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com2tag:blogger.com,1999:blog-4193169306787079445.post-54758109269120963632015-07-05T13:43:00.002-04:002015-07-05T13:43:58.353-04:00Kite pictures with a Raspberry Pi CameraMy brother Jim and his family were down here in Florida and we got it into our heads that it would be fun to take some aerial pictures. Now that I'm retired I'm too cheap to buy a GoPro and a multicopter, and besides those copters are just too annoying.<br />
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I cooked up a python program on one of my Raspberry Pi single board computers that would snap a picture once a second. The PiCamera has a resolution of about 5 megapixels.<br />
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Then my brother and his two kids figured out a way to rig it to a kite that I had bought when I was living in Singapore.<br />
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Here is a picture south along the beach near the apogee of the flight. The kite string is visible on the right.<br />
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This is Venice, Florida looking east.<br />
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Jim's neighborhood, with his house in the middle distance.<br />
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A nice view of the Gulf of Mexico and a few July 4th weekend beachgoers.<br />
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Jim and my nephew and myself discussing some crucial landing parameters.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRFY019mEjbwGrFvv7gQbnc5UnxbjWT6iHpN769MXDljvgDzZvHHcf_j0WTZ9oy1kaFyrKOmKT_ALgwzrRZ5vBbnU5TC14Sj3PNcfduGB5qnO3nquUVFczPskHg4VVO1vZsUMfroSY77E/s1600/kite1612.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRFY019mEjbwGrFvv7gQbnc5UnxbjWT6iHpN769MXDljvgDzZvHHcf_j0WTZ9oy1kaFyrKOmKT_ALgwzrRZ5vBbnU5TC14Sj3PNcfduGB5qnO3nquUVFczPskHg4VVO1vZsUMfroSY77E/s400/kite1612.jpg" width="400" /></a></div>
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Me and the kite nearly reunited.<br />
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My niece and nephew wrestling the kite back into its storage bag.WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-57369073635069783732015-05-03T09:54:00.000-04:002015-05-03T09:54:51.367-04:00Stained glassI'm sorry for not posting for a while. My everyday computer got jumped by Mr. Dead. I've therefore been
somewhat discombobulated however all is now sorted out . . . and I am thus
recombobulated. Then we had our three daughters and son-in-law down for Easter.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvbLQc_Q8-hqX2W4eC8vv7LATFCtT2ZW3vJe8MTxwqZXnyE-kIg9yA0l3ESg0EsVrbrf3rBXZr5gHQK4ZVFd3KqZY0XMJlFqoY0YM7u9fwh_hy_B88i-IUdup5inVRXFRdZWtUowvW9s4/s1600/IMG_0839.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvbLQc_Q8-hqX2W4eC8vv7LATFCtT2ZW3vJe8MTxwqZXnyE-kIg9yA0l3ESg0EsVrbrf3rBXZr5gHQK4ZVFd3KqZY0XMJlFqoY0YM7u9fwh_hy_B88i-IUdup5inVRXFRdZWtUowvW9s4/s1600/IMG_0839.JPG" height="320" width="240" /></a>Peg and I took a class in making stained glass. This is what happens when you're retired and so have too much time on your hands. We have this courtyard around the pool at our house. We often eat dinner out there, and entertain as well as use the pool and the outdoor kitchen. We have lights under the eaves but we were looking for something a little more subtle. We put candles on the tables and that led us to the idea of making some lanterns to put the candles in, which led us to the stained glass class. Or at least that's the way I remember it.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhAEWHzrhAdrfSM2JTXjonhyphenhyphen4Y6G_qBaDw0NzoqOp_qgW99Qm2vGuD-1tmERb9Fr4yo7O6lnNh5sV7Ie-3k3C1lRNQj6TjUWJbCET_Cu-TeUt9dM9xu2oZm-FWmMDPCood0bI-4SpGuNZI/s1600/IMG_0808.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhAEWHzrhAdrfSM2JTXjonhyphenhyphen4Y6G_qBaDw0NzoqOp_qgW99Qm2vGuD-1tmERb9Fr4yo7O6lnNh5sV7Ie-3k3C1lRNQj6TjUWJbCET_Cu-TeUt9dM9xu2oZm-FWmMDPCood0bI-4SpGuNZI/s1600/IMG_0808.JPG" height="400" width="300" /></a></div>
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Neither Peg nor I go in much for tchotchke, and after looking through the pattern books that seems to be stained glass' stock-in-trade. Thus, I think the lanterns will be our final projects for the moment. I'm glad I now know the techniques, however, so if some huge money-making opportunity opens up in the stained glass arena, I'm ready to take it on.<br />
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Here are some pictures of the ones that we made. <br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBcgG7vLdRwMLr_9Cu2PMjufCVxRmazBoRzYkU-dWm9X-UUOCL1iTMFEpdswCjl0gqnM16L078ZA2VpxW2bkU3svvGYuCxZIGsTxdpGsXhjYtFKJGvZEK8Lh_hl9zcZtp2vOov2ERqWG4/s1600/IMG_0819+-+Copy.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBcgG7vLdRwMLr_9Cu2PMjufCVxRmazBoRzYkU-dWm9X-UUOCL1iTMFEpdswCjl0gqnM16L078ZA2VpxW2bkU3svvGYuCxZIGsTxdpGsXhjYtFKJGvZEK8Lh_hl9zcZtp2vOov2ERqWG4/s1600/IMG_0819+-+Copy.JPG" height="640" width="480" /></a></div>
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Peg made these using a combination of stained glass and fused glass techniques. Fused glass involves partially melting glass in a kiln to soften the edges and (as the name implies) fuse the pieces together. <br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgAvXmwADFUjr2JpNLH4NWzQPk79xAcSkg6_X_N4kVVddNQhcP9igq8WUnhXZlEEItfsRRHfwwyH4kMwEaCM0MG1gV-UIQPDLcCZW_0CuGqgWXbL7-ZB-a8YxSygtcEaewNemndCSF1z4/s1600/IMG_0865.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"></a> <br />
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<br />WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-27272469760856334212014-12-17T08:26:00.004-05:002014-12-17T08:26:58.055-05:00Measuring Electricity with an ArduinoA few of us have been working on a project to try and figure out what is the most cost effective temperature at which to set our thermostats if we plan to be away for an extended period. I'll write about the details of that at a future date, but clearly an important factor in that determination is how much electricity our air conditioners use. That is a question that I have focused on recently.<br />
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FPL (Florida Power & Light) provides hourly data, as shown here.</div>
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For my purposes, however, this has a couple of drawbacks. First, I would have to pull it from the website every day. Second, the highest resolution is on an hourly basis and I am looking for much more detail than that.</div>
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I nosed around the internet and I found a website called <a href="http://www.desert-home.com/" target="_blank">Desert Home</a>. This is a fascinating collection of home automation projects with detailed how-tos. Dave from Desert Home referenced <a href="http://openenergymonitor.org/emon/" target="_blank">OpenEnergyMonitor</a>. They sell a bunch of products for doing this kind of monitoring, but they also have a large number of educational posts that give the theory behind measuring electricity. Since I'm retired and have more time than money I decided to build the tools myself.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvJTmAzlL2tqnNnWMsQGPf9rF_SXF8QSejTxJs1zNxqZQEyPpvVdcFFXZDqDZe1sXltffVwYID3umDLVuEjyfZzR0w34NcoiExNRu-123HOOh9y9d6by0YIjCL2Of6Kswna_yxkIVe2Ys/s1600/IMG_0510.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvJTmAzlL2tqnNnWMsQGPf9rF_SXF8QSejTxJs1zNxqZQEyPpvVdcFFXZDqDZe1sXltffVwYID3umDLVuEjyfZzR0w34NcoiExNRu-123HOOh9y9d6by0YIjCL2Of6Kswna_yxkIVe2Ys/s1600/IMG_0510.JPG" height="400" width="300" /></a>I ordered up some CTs (current transformers). They clip around the electrical feed lines coming into the house and produce a small current that is proportional to the large current that is flowing through the feed wires. You can see them near the bottom of the picture below. For those of you not familiar with household electricity, in the US we commonly use 120Volt 2-phase 60 Hertz current. That is, the voltage on each of the feed lines alternates between a root-mean-square voltage of +120V and -120V relative to the neutral wire (the thick white wire in the picture) 60 times per second. That's why there are two transformers in the picture, one for each feed line. Incidentally, the 60 cycle wave-forms on the two feed lines are 180 degrees out of phase (thus it's called 2-phase) with each other, so when one is at +120V the other is at -120V. Thus the potential between the two feed lines, rather than between the feed line and the neutral, alternates between +240V and -240V 60 times per second. That's how you get 240V for your electric dryer or pool pump or whatever. But I digress.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBZQHgghMw3eyUorbgKRj7X6cLmTcv0LrK3sXWwOhgOLQFRurNnvTlhrkfSbm9n7edYi2DArVH6qR8MsDnXdlKM22lUkY9UbIRfD38g2wbHo9knGnDZ2zYw4Q5tJJYE37ag4I-u9ah2aY/s1600/VoltageCurrent.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBZQHgghMw3eyUorbgKRj7X6cLmTcv0LrK3sXWwOhgOLQFRurNnvTlhrkfSbm9n7edYi2DArVH6qR8MsDnXdlKM22lUkY9UbIRfD38g2wbHo9knGnDZ2zYw4Q5tJJYE37ag4I-u9ah2aY/s1600/VoltageCurrent.jpg" height="300" width="400" /></a>You might think that's almost the end of the story, but you would be mistaken. The way power companies charge for electricity is on the basis of "real power." Real power is the instantaneous voltage multiplied by the instantaneous current, giving the instantaneous (real) power (in watts). The reason that's important, the folks at OpenEnergyMonitor taught me is that electrical devices draw different amounts of current at different voltages. The plots of voltage and current draw might look something like this. So what you have to do is measure the voltage and current a bunch of times a second, multiply them, and then total them up. </div>
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Okay, so here is what my setup looks like with all the covers off.</div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4NbvVV_79CSMEBLUFBTFSlwdlbzueXeOP3mqVFNMkhlu_Sn9tyC_Bmh24CcgkR7Ub7ZUz5-1-z_spuBCoOBWt05fE7ZXtmbnVYhjB2GYj7fR3FYPkD4tzKzO1x9FI1LWX1d7W514qlKM/s1600/IMG_0513.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4NbvVV_79CSMEBLUFBTFSlwdlbzueXeOP3mqVFNMkhlu_Sn9tyC_Bmh24CcgkR7Ub7ZUz5-1-z_spuBCoOBWt05fE7ZXtmbnVYhjB2GYj7fR3FYPkD4tzKzO1x9FI1LWX1d7W514qlKM/s1600/IMG_0513.JPG" height="480" width="640" /></a></div>
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I have two 200amp panels, each with two feeds so I have four measurements that I take. I ran a piece of conduit from each panel to the blue box. I then connected them to a circuit I built, again based on guidance from <a href="http://openenergymonitor.org/emon/" target="_blank">OpenEnergyMonitor</a> that conditions the current coming from the transformers so that it can be measured using an Arduino microcontroller. You can see it hanging from the wires in the bottom of the above picture. You will remember that the two components needed to measure the power used are current and voltage. That's why there are two "wall wart" transformers plugged in in the picture. One powers the Arduino and one just delivers the alternating current waveform to the conditioning circuit.<br />
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Here is a closer picture of the circuit stacked on top of the Arduino. And here is everything all buttoned-up.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7OoZjginJKvA9d2zDa53SnI4xmpdcz9VD_0RM_qimRkwqLCqKDiolhQQLfE3FwzwZyEq8Z0ufzNqKIHzxlwj0TstxMVW4coeN2IzUXDHMkaFi622QWWwe_ECmCVXjxjjFrPYKZloCjj4/s1600/IMG_0522.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7OoZjginJKvA9d2zDa53SnI4xmpdcz9VD_0RM_qimRkwqLCqKDiolhQQLfE3FwzwZyEq8Z0ufzNqKIHzxlwj0TstxMVW4coeN2IzUXDHMkaFi622QWWwe_ECmCVXjxjjFrPYKZloCjj4/s1600/IMG_0522.JPG" height="300" width="400" /></a></div>
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The Arduino takes around 45,000 readings a minute from each of the four current sensors. That may seem like a lot but you must remember that the voltage is alternating 60 times per second so 45,000 readings per minutes is 750 readings per second and if there are 60 cycles per second that is only 12.5 readings per cycle. The Arduino takes the readings and averages them for one minute then stores that number. Then every five minutes it uploads the data to a small computer up in my office. That computer stores the information in a SQL database that I can access via web browser from any computer on my network.<br />
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I was a little concerned that I was only getting about 12.5 readings per cycle but the electrical usage that I measure is within less than 2% of what Florida Power and Light reports so it's pretty close, and I think I can get it even closer if I tinker with my calculations a little.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgc7SVPE6GZb7s8wToOF6MLEnTH842B67o2PE3jsT5loUupX1_X5hlG_olpTDeaWBYN5shpXU92JLD5eyyw8B0W0WXjJjpfFAmD9W9w2RC83sYsLUpBkXZnNFrHdyGdY3LFMOhHG9aCST8/s1600/All+4+chart.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgc7SVPE6GZb7s8wToOF6MLEnTH842B67o2PE3jsT5loUupX1_X5hlG_olpTDeaWBYN5shpXU92JLD5eyyw8B0W0WXjJjpfFAmD9W9w2RC83sYsLUpBkXZnNFrHdyGdY3LFMOhHG9aCST8/s1600/All+4+chart.jpg" height="480" width="640" /></a></div>
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Here is a graph of the electrical usage on a minute by minute basis. The four colors are the four electrical feeds. I know what circuits are connected to what feeds so I can use the information to track down what equipment is using the electricity. I've just gotten this working but there are some features that jumped out at me. Specifically, the blue, yellow, and red lines all have trains of more or less evenly spaced peaks. The blue ones repeat about once every forty-five minutes, the yellow once every two hours, and the red once an hour.<br />
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I showed them to Peg and asked her what she thought they were. She said, "What about the refrigerator?" I said it couldn't be that because they each have periods of even units of time, forty-five minutes, one hour, two hours. They must be things that are running on timers. I unplugged my cable box and TV. I unplugged the printer. I turned off the breaker on the security system...nothing. As it turns out they are three different refrigerators. The red one is the one in the kitchen, the yellow one in the outdoor kitchen, and the blue one a small beverage 'fridge that we have in the guest room. Who'd have thought? Well, Peg I guess.<br />
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That's it for now. As I said earlier, we're working on a project to measure air conditioner usage and I'll give you an update on that in a later post.<br />
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WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com4tag:blogger.com,1999:blog-4193169306787079445.post-76232945237905969152014-12-04T07:57:00.000-05:002014-12-04T07:57:11.012-05:00Housewarming presentI've mentioned in the past that my brother John and his wife Doreen are building a vacation home here in Venice. It was supposed to be done in July, then August, then September. Well, I guess new houses asymptotically approach completion, half way, half way half way but never quite there. Each time I go by there are a tradesperson or two over there tinkering with something. However, they were down a few weeks ago, and they got a certificate of occupancy and actually stayed in the house. I thought that was official enough to give them their housewarming present.<br />
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It's what is sometimes called an ambient device. The idea is that is kind of conveys information to you almost subliminally. For instance, I've seen these small globes that sit on the table in your living room and glow green when the stock market is going up or red when the stock market is going down.<br />
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Well, down here in Florida we focus a lot on the weather. Considering how little weather we actually have here relative to the rest of the country it's a peculiar fixation, but it is what it is. Here is a picture of the device. It has two display modes, one is temperature and one is barometric pressure.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8q7oKaUv3eSptyqxshbe6HGJs-YWybfrxxGciBwD09DuB768zNfb2-eSGg9ujB5mG_2lYWWB-I8cHFLNlbtX9uqYd0JkdVmPctse1P39XiaWslz_8WemlzHMp-QkwQRyFbPWoPbdStwA/s1600/IMG_0441.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh8q7oKaUv3eSptyqxshbe6HGJs-YWybfrxxGciBwD09DuB768zNfb2-eSGg9ujB5mG_2lYWWB-I8cHFLNlbtX9uqYd0JkdVmPctse1P39XiaWslz_8WemlzHMp-QkwQRyFbPWoPbdStwA/s1600/IMG_0441.JPG" height="400" width="300" /></a></div>
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Here it is displaying a temperature of 83 degrees Fahrenheit. The top two lights represent the tens place and the rest represent the ones place.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsOrhiwEE4KqZsDbHWo0KGiVDWIidDGjibQ5X024cbl_FYLZU8OFkwPy9mu8s-0j5NJBWBr2GcgNysPn25bwM4dbmqj0XA4gKygpjRXJm5BjI9PUYpa1z10jQl8Lni9LkJbI7wz1GNIkI/s1600/IMG_0499.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsOrhiwEE4KqZsDbHWo0KGiVDWIidDGjibQ5X024cbl_FYLZU8OFkwPy9mu8s-0j5NJBWBr2GcgNysPn25bwM4dbmqj0XA4gKygpjRXJm5BjI9PUYpa1z10jQl8Lni9LkJbI7wz1GNIkI/s1600/IMG_0499.JPG" height="400" width="300" /></a></div>
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In Barometric Pressure mode the top light shows the current pressure, the next one down the pressure three hours ago, the next one three hours before that, etc. etc. Here we can see that the current pressure is between 30.00 and 30.20 inches of mercury, down slightly from three hours ago.<br />
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The device is made from alternating layers of cedar and acrylic. In the center of each acrylic layer is an RGB LED. It's really three LEDs (Red, Green, and Blue) built into one. Each color can be illuminated at 4096 different intensities and thus, theoretically, each LED can display 4096 x 4096 x 4096 = 68,719,476,736 different colors. Of course humans can't discern anywhere near that many colors so I settled on Red, Orange, Yellow, Green, Blue, Indigo, and Violet (Roy G Biv) White and Black (no light at all.)<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdJbspOpmSwBcen1CZYwGnNQZlcXXB8a1Pz5Oev1_7ePcYWbdEs_1S07HMf7lJ6I61St2epy6dJ_Wc405J4jzMzCNpHFLxR8p1JwgQZ9U73RacKnK5Ftu70IOlTn9mXNNVAsmmV8K7Pu4/s1600/IMG_9585.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdJbspOpmSwBcen1CZYwGnNQZlcXXB8a1Pz5Oev1_7ePcYWbdEs_1S07HMf7lJ6I61St2epy6dJ_Wc405J4jzMzCNpHFLxR8p1JwgQZ9U73RacKnK5Ftu70IOlTn9mXNNVAsmmV8K7Pu4/s320/IMG_9585.JPG" width="320" /></a>I went over to Lowes and picked up cedar board meant to be a fence rail and ran it through the planer. Then I cut it into isosceles triangles.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFijOudHjr9gQ6henZLUu3A3XtFz7leoFlf7qVMDQZWgwhXSde-lLoZwYyOhcA5qWnFpQBYNMVyRLhOHot8zB4fAR6LiHu_nbCtGTagZGzldPLu27OaMCPmPjsySsr9j-zmUCa7LJe2kQ/s1600/IMG_0123.JPG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFijOudHjr9gQ6henZLUu3A3XtFz7leoFlf7qVMDQZWgwhXSde-lLoZwYyOhcA5qWnFpQBYNMVyRLhOHot8zB4fAR6LiHu_nbCtGTagZGzldPLu27OaMCPmPjsySsr9j-zmUCa7LJe2kQ/s320/IMG_0123.JPG" width="320" /></a><br />
I made some jigs and glued the cedar into squares.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhS-b0Xfzophn-pF2ZdckaURKkwzSUwjzbFye0f-lUNjXLt3cP9ZtGJOfBYXvuRT77_uCtZ5UdYce_gyvX3Uv7-CEvLIUWIuM3wwNToapJRmQkHSAuQrBkJh8RMf-GcU_ha4pBleVB68rY/s1600/IMG_0121.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhS-b0Xfzophn-pF2ZdckaURKkwzSUwjzbFye0f-lUNjXLt3cP9ZtGJOfBYXvuRT77_uCtZ5UdYce_gyvX3Uv7-CEvLIUWIuM3wwNToapJRmQkHSAuQrBkJh8RMf-GcU_ha4pBleVB68rY/s200/IMG_0121.JPG" width="320" /></a></div>
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Then I made another jig to drill holes to fasten them together and for the LEDs and wires.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTqzc7nJta6zI4KTr3sfEFsDikJxaXJRLYP2iBWCSQP0RCnMidVXUxUTmut9ynHtfQFhEQmE_KHZXqVmvtWmgsL1SliuMiltUIYF5RHOGNjN0lZLUbhdAKsrtvT53GZlFzqtEcm49z-sw/s1600/IMG_0122.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTqzc7nJta6zI4KTr3sfEFsDikJxaXJRLYP2iBWCSQP0RCnMidVXUxUTmut9ynHtfQFhEQmE_KHZXqVmvtWmgsL1SliuMiltUIYF5RHOGNjN0lZLUbhdAKsrtvT53GZlFzqtEcm49z-sw/s200/IMG_0122.JPG" width="320" /></a></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDExq-qrSZ9HUj7uy7PPpVW4t05mNCMyS4D3D9D__1Reo9GQroEDp6TSdI0H4wMijYRRIncCR67vbJy_Cg2kXJDIAzUnC4IWQP-4qiTKs6aLKuhyphenhyphenvgDldbLppnfOj7kB07MqkWPW2hVHQ/s1600/IMG_0119.JPG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDExq-qrSZ9HUj7uy7PPpVW4t05mNCMyS4D3D9D__1Reo9GQroEDp6TSdI0H4wMijYRRIncCR67vbJy_Cg2kXJDIAzUnC4IWQP-4qiTKs6aLKuhyphenhyphenvgDldbLppnfOj7kB07MqkWPW2hVHQ/s320/IMG_0119.JPG" width="400" /></a>I made a bigger square of cedar for the bottom and hollowed it out for all the electronics. Then fastened them all together.</div>
<br />WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-20231894365311693052014-10-31T10:47:00.000-04:002014-10-31T10:47:42.911-04:00What's the difference between a coffin and a casketHistoric Spanish Point in Osprey, Florida is re-enacting a Victorian funeral for Halloween. (Some people know how to have fun.) A few weeks ago Kara Pallin from over there called me up and asked if I could make them a casket in the Victorian style. I told her that if she could show me a few pictures of the kind of thing she was looking for I could probably cook it up. Well, I just thought I'd show a few pictures.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilX0ELhlj1fWiLXSgfJad3z9YW5QCZOn4WQuSFjTXTZ-OSJPiEJg1F9T1XRExrsswRAnPu_k74vvqLg3GbVoGedvpl94OSOqL2yD9tTKiw9FqrP-tUtqHi_3KOnHs_cgXAgjXNHgYNDHQ/s1600/IMG_0425.JPG" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilX0ELhlj1fWiLXSgfJad3z9YW5QCZOn4WQuSFjTXTZ-OSJPiEJg1F9T1XRExrsswRAnPu_k74vvqLg3GbVoGedvpl94OSOqL2yD9tTKiw9FqrP-tUtqHi_3KOnHs_cgXAgjXNHgYNDHQ/s1600/IMG_0425.JPG" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Built out of pine and plywood.</td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipv4Ov2ONxvjoPWdPlDJSp_p1G6NjTC1TzLO8zHRcMdTNgzJUTKQG_Lrz6X3Ahj5jn76N4fQH6QqT13XeUi-keC2uBF5sBSzocSslY-z8cZTtexKO3HjjvGnO13YPsJAEhhCWwxYCGSTk/s1600/IMG_0435.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipv4Ov2ONxvjoPWdPlDJSp_p1G6NjTC1TzLO8zHRcMdTNgzJUTKQG_Lrz6X3Ahj5jn76N4fQH6QqT13XeUi-keC2uBF5sBSzocSslY-z8cZTtexKO3HjjvGnO13YPsJAEhhCWwxYCGSTk/s1600/IMG_0435.JPG" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Painted classic black</td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpyfn2VlteyjC8_ag2AQKwBwrFYhBOoXy-Gbambu6RXrg0A2CuOzOUT7DW7fTqAQNpg8karkTNk3VLElI1MYrtOEjzDrSNeYRJ5eq1SOp3E2wUfd_8U8sJ94Yydz8haz4o2nC1l7KB8Bo/s1600/IMG_0438.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpyfn2VlteyjC8_ag2AQKwBwrFYhBOoXy-Gbambu6RXrg0A2CuOzOUT7DW7fTqAQNpg8karkTNk3VLElI1MYrtOEjzDrSNeYRJ5eq1SOp3E2wUfd_8U8sJ94Yydz8haz4o2nC1l7KB8Bo/s1600/IMG_0438.JPG" height="300" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">With fittings added, including period appropriate decorations</td></tr>
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<br />Ok, that's it. Oh, by the way, while they are often used interchangeably, a casket is usually rectangular in shape while a coffin is the elongated trapezoid of this one.<div>
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Anybody who's interested, just hop in.</div>
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Happy Halloween.<br /><br />
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WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-20498096474478080102014-09-23T13:05:00.000-04:002014-09-23T13:05:23.002-04:00Solar calendarYesterday was the equinox, equal day and night. It's not really equal day and night for a couple of reasons. One, daylight is generally considered to begin when the first part of the disk of the sun is visible above the horizon, and to end when the last of the disk is no longer visible. Whereas, the equinox refers to the center of the disk of the sun. Two, the curvature of our atmosphere causes refraction that allows us to see the sun before it is actually above the horizon, but I digress.<div>
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For some time I have been thinking about building a device that is kind of the equivalent of a sun dial, but instead of telling the time it would tell the date. We all realize that the fact that the earth is tilted relative to the plane of the ecliptic gives us our seasons. As the earth moves around the sun that tilt causes the sun to appear higher in the sky at some times of the year than at others. I wanted to use the changing height of the sun, and thus the change in the location of the shadows that it casts, to mark the passage through the year. It would work kind of like this.<div class="separator" style="clear: both; text-align: center;">
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I also wanted it big enough so that the day-to-day changes would be observable as a way of connecting with the movement of the earth through space.<br />
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As it turns out I have a wall in the courtyard of my home in Florida that was crying out for some decoration, So here it is.<br />
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My plan was to cut pieces of wood in short arcs and assemble them end-to-end. I was discussing the project with my friend Jim Nemec, who is, among other things, a boat builder. He allowed as how that was the incorrect way to do it, and that I should cut thin strips and laminate them into a curve. As it turns out, he was correct.<br />
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I bought a piece of mahogany and ripped it into strips a little over five feet long.<br />
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Then I cut some particle board to form an arc of a circle with a ten foot diameter, the arc being a little longer than my mahogany strips, and screwed the particle board to my workbench.<br />
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Jim and I then slathered a bunch of epoxy onto the strips and clamped them to the form.<br />
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The next day I popped it off, sanded it and trimmed it.<br />
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Then I finished it with boat varnish.<br />
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As luck would have it, I finished it just in time because, as I said earlier, yesterday was the autumnal equinox (in the northern hemisphere or the vernal equinox in the southern hemisphere). That was important because I want the equinoxes to be exactly in the middle of my calender. Thus, I had to note the position of the shadow yesterday, and mount it such that it fell right in the middle, and such that the brass rod that I attached to the wall was at the center of the circle determined by the arc of the calendar.<br />
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Getting it in the exact position, both technically and aesthetically was no mean feat and required the assistance of my brother John and his wife Doreen, holding...looking...holding...marking.... But it's up, and here it is.<br />
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I have a measuring tape on the calendar so I can record the position of the shadow each day. I'm not sure how I'm going to mark the days on the calendar, But I have a year of recording before I need to figure that out. I'll report back next September.<br />
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WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com2tag:blogger.com,1999:blog-4193169306787079445.post-59264444075776685252014-09-15T11:21:00.001-04:002014-09-15T11:21:56.839-04:00Basket BenchThese projects have a lot of hidden costs.<br />
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Peg thought we needed a headboard for our bed down here in Florida. She opined that I could probably whip something up in not too much time for not too much money. We haven't decided whether to buy a king size bed (I'm not sure you realize how much mattresses cost) or stick with the queen size, so while we're wrestling over that I made a bench for the foot of the bed that would work for either size.<br />
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I made the bench from cherry. Here is the top with mortise and tenon joints, and biscuits for the mitered corners, and here it is assembled.<br />
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This is the body of the bench where I used half-lap joints.<br />
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I used pre-woven caning material for the seat sections of the top, the sides and the back.<br />
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Here is the body assembled.<br />
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These are all the parts, varnished and ready to put together.<br />
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This is the completed top ...<br />
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and the back with the caning installed.<br />
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All put together.<br />
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And in place. I'll give you an update on the headboard once we decide that mattress question.WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-39288936971442355082014-06-30T22:27:00.000-04:002014-06-30T22:27:14.259-04:00Wedding PresentIt was pointed out to me that I never posted anything about the chest of drawers that I made for my daughter and her husband as a wedding present. I built it in what's commonly referred to as the Greene & Greene style, after Charles and Henry Greene, brothers who were architects and furniture makers who worked in the first part of the 20th century, and who were strongly influenced by the Arts & Crafts movement.<div class="separator" style="clear: both; text-align: center;">
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I built it from lyptus, a farm grown hardwood similar in appearance and workability to true mahogany.</div>
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Here I am working on laying out the boards for the top of the cabinet. This can be a fairly time-consuming process if one wants to make the transition from board-to-board appear as natural as possible.</div>
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Now I am edge-gluing the boards. This can be tricky, especially when working by oneself because the boards must be carefully aligned, with no gaps, and clamped tightly enough for a good joint but not so tightly that all the glue is squeezed out.</div>
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And here is the assembled top before the "breadboard ends" are added. There is a fair amount of engineering that goes into making pieces of furniture of this size out of wood, because wood expands and contracts due mainly to changes in humidity. Further, almost all this expansion and contraction occurs across the grain and almost none parallel to the grain. Thus, if not properly designed a piece of furniture can pull itself apart.</div>
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This is the skeleton of the piece, test-fitted together.</div>
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Here you can see the sides and back of the cabinet. Those panels that fit between the rails and stiles are not glued in place, but rather just float in grooves. Again, this is to allow for expansion and contraction of the wood.</div>
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This is the layout of the drawer fronts. I am again matching grain for the best appearance and working on the arrangement of the carved ginkgo leaves, before I inlay them. The leaves are carved from a wood called yellowheart. I also patterned the drawer pulls after some Greene & Greene architectural details.</div>
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Finally, here is the completed piece. I wanted it to be able to be used as either a dresser or a dining room side-table. For that reason I used hidden ball-bearing drawer glides so if it was used to store dishes or other heavy items the drawers would be up to the task.</div>
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Well that's it. I hope you like how it came out.</div>
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WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com1tag:blogger.com,1999:blog-4193169306787079445.post-75186412025483433942014-05-21T10:53:00.000-04:002014-05-21T10:53:04.090-04:00Intervalometer and the starsI periodically get an email newsletter from Make Magazine. In a recent issue Ron Risman had an article about how to take time-lapse pictures of the stars. You can find the article <a href="http://makezine.com/projects/how-to-capture-breathtaking-time-lapses-of-the-night-sky/?utm_medium=email&utm_campaign=Make%20Newsletter%20%20DIY%20Space&utm_content=Make%20Newsletter%20%20DIY%20Space+CID_956257a88da257143cf40f20db16c8fd&utm_source=Email%20Campaign&utm_term=How%20to%20Capture%20Breathtaking%20Time-Lapses%20of%20the%20Night%20Sky" target="_blank">here.</a> I thought it would be fun to try, but I don't have a digital SLR camera. As luck would have it, my brother Jim does, and he was coming down to Florida for a long weekend a couple of weeks hence. He brought his camera down and we thought we'd give it a try.<br />
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Just to manage expectations, we don't yet have any pictures worth looking at. We followed the guidance in Ron Risman's article, but realized we needed an intervalometer. Now I didn't actually know what that was but Jim educated me, saying that is was a device that could trigger a camera at specified intervals, hence the name. Further he explained that his Olympus camera had an infrared receiver that could be used to trigger the shutter using a hand-held remote, which he didn't own.<br />
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We jumped on the internet and found some work by jmknapp that used an Arduino microcontroller and an infrared LED to emulate the remote. That information can be found <a href="http://forum.arduino.cc/index.php?topic=7791.0;wap2" target="_blank">here.</a> As it turns out, I had an Arduino microcontroller and an IR LED. I quick downloaded jmknapp's software, and made a few little changes so it would trigger the shutter of Jim's camera at intervals we could set.<br />
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And here it is. Ok, I know, not much to look at, but this is the proof-of-concept stage. We didn't get this all done until the last evening that Jim was going to be down here. We took a few pictures, changed some settings, took a few pictures, etc. The moon was just into its second quarter so it was bright enough to wash out the pictures, and it took us a while to get the focus right, but we were closing in on it.<br />
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Since Jim left I have been working on improving the user interface and functionality and here's what I have.<br />
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For testing purposes I have temporarily replaced the IR LED with the red one you can see in the picture so I can see if it's working with the unaided eye.<br />
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As you can see I added a Delay feature so Jim can have it wait for a specified number of hours/minutes/seconds before it starts taking pictures. I also let him have it stop taking pictures after a certain amount of time or a certain number of pictures.<br />
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I also added another mode. I included a Passive Infrared sensor (PIR). Jim gets lots of deer and other wildlife in his yard, and in PIR mode the camera will be triggered by motion in its field of view.<br />
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The semi-circles at the bottom of the screen are indicators of the sensitivity of the PIR, which can be adjusted via a knob.<br />
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All that's left to do it put it in some kind of case, but I thought it would be good to test it in the field first. I'll be going up to Chicago in a few weeks and we'll try it out then. I'll post any time-lapse videos that are worth looking at.WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0tag:blogger.com,1999:blog-4193169306787079445.post-29962664530481509842014-04-20T17:13:00.000-04:002014-04-20T17:13:05.898-04:00Secret Knock Gumball MachineI want you to know that just because I haven't posted much recently it doesn't mean that I haven't been busy. I've been working on a housewarming present for by brother John and his wife Doreen. They are building a house and it's supposed to be finished in August. That project is well along now, but it's a secret so I can't blog much about it until I give it to them.<div>
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I do want to tell you about something I made a while back, though. It was adapted from an article in Make Magazine, issue 25 called Secret-Knock Gumball Machine by Steve Hoefer. As the name implies, it is a gumball machine, but instead of putting in money, you knock on it in a particular pattern. If you get the pattern right it gives you a gumball. Below is a video of one of them that I made.</div>
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The default knock, as shown is the video is "shave-and-a-haircut" but can be changed to anything the user would like. I heartily encourage you to look over the article. I think the programming that Hoefer did is particularly clever and could be used to open a door or a treasure box, or to trigger any other thing.</div>
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I built the one shown in the video for my brother Jim. However, I modified the design in the article in several respects. First, I made the dispensing wheel horizontal, rather than vertical. I did this so that it was more patterned after conventional gumball machines. Second, I added a switch so that the machine knew when it had fed a gumball, and I changed the software to add some strategies like reversing the feed wheel if a gumball did not feed in a certain amount of time, thus making the dispensing process more dependable.</div>
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I made the one for Jim out of wood. I was happy with it, and it worked pretty well, but it would occasionally jam. Nothing would break, but on rare occasions you had to turn it over and then set it back upright to clear it.</div>
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While I was building Jim's machine my sister Monica and her husband Jim visited, and I showed them how it was going to work. Usually when I show my family what I'm building they watch and say something like "Oh, that's very interesting. . . . What should we do for lunch?" but Monica and Jim asked me to demonstrate it a couple of times and asked a number of questions about the details of the design.</div>
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Therefore, I decided to build a second machine, this one for Monica. I wanted to make out of acrylic, and I wanted the feed to be more dependable.</div>
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I knew that the thing that was causing the jamming was the hopper mechanism that funneled the gumballs to the feed wheel. I was experimenting with a bunch of sculpted designs that would guide the gumballs to the holes in the feed wheel but wouldn't allow two or more gumballs to block up the mechanism. My son-in-law Tim looked at it and said, "You're over-engineering it. Get rid of the hopper and just let the gumballs fall down the throat of the machine and drop onto the feed wheel. They'll fall into the holes without jamming."</div>
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I realized that he was right. The only time it might not feed continuously is when there are only one or two or three gumballs left, but that is only a fraction of the time. Mostly it will have a bunch of gumballs and they'll easily drop into the feed wheel.</div>
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Above is a picture looking down the throat of the machine. The wheel with the holes in it turns and as it does a gumball that is in one the holes passes over the feed chute and the gumball falls out, rolls down the chute, and comes out the front of the machine. The last time I talked to Monica about it they had just about gone through the entire box of gumballs that I had given them with the machine (the standard size package has 850 gumballs) and there had been no jamming or mis-feeding.</div>
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This is a great project. People are fascinated by it. Again, read Steve Hoefer's article and look at his blog posts on Makezine.com.</div>
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WAKhttp://www.blogger.com/profile/04866373490827292416noreply@blogger.com0