{"id":6494,"date":"2019-05-24T17:08:24","date_gmt":"2019-05-24T21:08:24","guid":{"rendered":"https:\/\/glyphpress.com\/talk\/?p=6494"},"modified":"2020-10-26T14:00:32","modified_gmt":"2020-10-26T18:00:32","slug":"s16-forward-voltage-current-limitation-and-preventing-clipping","status":"publish","type":"post","link":"https:\/\/glyphpress.com\/talk\/2019\/s16-forward-voltage-current-limitation-and-preventing-clipping","title":{"rendered":"S16: Forward Voltage, Current Limitation, and Preventing Clipping"},"content":{"rendered":"\n<p>The purpose of <b>the S16 analog synthesizer communication network protocol <\/b>is to make direct, machine-to-machine collaboration between experimental musicians safe and easy, guided by curiosity. Naturally, as I\u2019ve been refining and experimenting, I\u2019ve been finding ways to make it more difficult. But at least I don\u2019t think it\u2019s less safe.<\/p>\n\n\n\n<!--more-->\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"1024\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-1024x1024.jpeg\" alt=\"\" class=\"wp-image-6519\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-1024x1024.jpeg 1024w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-150x150.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-300x300.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-768x768.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-1200x1200.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-250x250.jpeg 250w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-400x400.jpeg 400w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-100x100.jpeg 100w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-1536x1536.jpeg 1536w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/06903C54-95BD-4816-9F5F-737AD77201AC-e1588714740828-2048x2048.jpeg 2048w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><figcaption>Transmitter is on the left, sending control voltage through the S16  cable to the receiver on the right. There are three receiver components:  an LDR-based transparent single-stud LEGO plate, another LED-based  black, single-stud LEGO plate with its stud removed, and the  phototransistor solution discussed in this article. The column on the  right from top to bottom is a grey LEGO barrel for strain relief on the  cable and a black Technic pin connector containing the LED that converts  voltage to light, embedded in a Technic half-pin. Beneath is is another  pin connector containing a half-pin that houses a phototransistor that  is used to convert the light to a voltage.<\/figcaption><\/figure>\n\n\n\n<p>You\u2019ll recall that the spec for <a href=\"https:\/\/glyphpress.com\/talk\/2019\/the-s16-analog-music-network\">the S16 communication network<\/a> requires that:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>The receiver be designed to receive control voltage signal through optical coupling and a LEGO interface.<\/li><li>The receiver is responsible for their design from the specified LEGO connection back into their own module \u2014 the spec doesn\u2019t care what you do with the signal, just that you receive it somehow.<\/li><li>The transmitter offers a signal of varying brightness through a LEGO connector<\/li><li>The transmitter is responsible for their design up to the specified connection to the receiver \u2014 the spec doesn\u2019t care how you generate the varying brightness, just that it vary according to your artistic intentions and technical compromises.<\/li><li>Signal degrades gracefully as the transmitter\/cable\/receiver coupling is less optimal. The perfect setup will transmit and receive well. A less good one will distort the signal, but that still might be interesting. If it\u2019s totally wrong, either nothing will happen or the cable will burn out, which is no big deal.<\/li><\/ul>\n\n\n\n<p>The following is trying to improve the specific design to give other musicians a starting point by sharing my experience. There are other people with far, far greater understanding of both synthesizers and electronics, and they may want to find their own optimalities.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Receiver components<\/h2>\n\n\n\n<p>The biggest revelation so far is discovering that using a <i>phototransistor <\/i>(a component that uses light to control the flow of current the way a transistor uses a small voltage to control a larger one) as a receiver component is <i>extremely&nbsp;<\/i><span>simple. It outputs a change in transmitted brightness as a change in voltage, which is what your synthesizer module was expecting anyway. And it\u2019s a change in voltage that is completely in agreement with your module, from ground level to maximum because the voltage is coming right from your own power system, whatever way you\u2019ve designed it.<\/span><\/p>\n\n\n\n<figure class=\"wp-block-image\"><img loading=\"lazy\" decoding=\"async\" width=\"1038\" height=\"249\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E6CDA8CB-D6CA-4C8F-A0C9-A625D865B318-1038x249.jpeg\" alt=\"\" class=\"wp-image-6497\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E6CDA8CB-D6CA-4C8F-A0C9-A625D865B318-1038x249.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E6CDA8CB-D6CA-4C8F-A0C9-A625D865B318-150x36.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E6CDA8CB-D6CA-4C8F-A0C9-A625D865B318-300x72.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E6CDA8CB-D6CA-4C8F-A0C9-A625D865B318-768x184.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E6CDA8CB-D6CA-4C8F-A0C9-A625D865B318-1200x288.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E6CDA8CB-D6CA-4C8F-A0C9-A625D865B318-400x96.jpeg 400w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><figcaption>Left to Right: 3mm photodiode, LEGO Technic \u201chalf-pin\u201d, LEGO Technic \u201cpin connector\u201d. The incoming data cable plugs in on the right, with its control voltage converted to brightness. Superglue the phototransistor into the half-pin, then just click it into the tube connector. It\u2019s probably best to leave the half-pin unglued because it facilitates repair and modification, allowing the pin connector to be a part of the case while the sensor is a part of the circuit board inside. When you need to fix something, you just click it apart!<br><\/figcaption><\/figure>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"aligncenter is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/0FCAB676-0D42-4F18-84AB-BD39968CB04D-e1558729193568-1038x474.jpeg\" alt=\"\" class=\"wp-image-6516\" width=\"576\" height=\"263\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/0FCAB676-0D42-4F18-84AB-BD39968CB04D-e1558729193568-1038x474.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/0FCAB676-0D42-4F18-84AB-BD39968CB04D-e1558729193568-150x69.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/0FCAB676-0D42-4F18-84AB-BD39968CB04D-e1558729193568-300x137.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/0FCAB676-0D42-4F18-84AB-BD39968CB04D-e1558729193568-768x351.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/0FCAB676-0D42-4F18-84AB-BD39968CB04D-e1558729193568-1200x548.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/0FCAB676-0D42-4F18-84AB-BD39968CB04D-e1558729193568-400x183.jpeg 400w\" sizes=\"auto, (max-width: 576px) 85vw, 576px\" \/><figcaption>The phototransistor glued in place with heatshrink over the exposed end to reduce light interference. This end goes inside the module\u2019s case, so you might think it would be safe from interference, but there are always blinking lights SOMEWHERE.<\/figcaption><\/figure><\/div>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"alignright is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AFE94E1B-1175-4B0A-9C2F-91EAC9D81C7F-e1558657527477-941x1024.jpeg\" alt=\"\" class=\"wp-image-6508\" width=\"164\" height=\"178\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AFE94E1B-1175-4B0A-9C2F-91EAC9D81C7F-e1558657527477-941x1024.jpeg 941w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AFE94E1B-1175-4B0A-9C2F-91EAC9D81C7F-e1558657527477-138x150.jpeg 138w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AFE94E1B-1175-4B0A-9C2F-91EAC9D81C7F-e1558657527477-276x300.jpeg 276w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AFE94E1B-1175-4B0A-9C2F-91EAC9D81C7F-e1558657527477-768x836.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AFE94E1B-1175-4B0A-9C2F-91EAC9D81C7F-e1558657527477-1200x1306.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AFE94E1B-1175-4B0A-9C2F-91EAC9D81C7F-e1558657527477-400x435.jpeg 400w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AFE94E1B-1175-4B0A-9C2F-91EAC9D81C7F-e1558657527477.jpeg 1584w\" sizes=\"auto, (max-width: 164px) 85vw, 164px\" \/><figcaption>This LDR is glued to the back of a 1&#215;1 round LEGO plate. The single stud connection turned out to be pretty dicey. It seemed like it would get knocked out a lot in performance.<\/figcaption><\/figure><\/div>\n\n\n\n<p>I\u2019d been using a <i>light-dependent&nbsp;resistor<\/i>&nbsp;as a receiver before. They\u2019re extremely simple and inexpensive (around 3.5\u00a2 apiece when purchased in the kind of bulk you\u2019d want anyway). They output variations in <i>current<\/i><span>&nbsp;(not voltage)<\/span>, though, so they needed to be coupled with another resistor to make a voltage divider, and I was having a hell of a time finding the properly tuned values for them. It seemed like the colors of light that defined their resistance was <i>really<\/i><span>&nbsp;specific, and it looks like it varies wildly from model to model.<\/span><\/p>\n\n\n\n<p>By contrast, phototransistors <a href=\"https:\/\/www.amazon.com\/Flat-head-PHOTOTRANSISTOR-Transistors-Phototransistor-450-1080nm\/dp\/B077XQF8MN\">cost more<\/a>, but don\u2019t require any further circuitry at all to supply voltage and are tuned at the factory to have useful values. However you\u2019ve designed your synthesizer module, wherever it takes control voltage, you hook up the phototransistor to your V+ rail (or whatever your cockamamie power scheme is) and then solder the other end to your input, and you\u2019re set. So, for instance, if your module is built around an Arduino, you literally plug one end into 5V and one end into the analog pin you\u2019re reading, and you\u2019re done. Glue it into a LEGO and you can receive signal! <\/p>\n\n\n\n<div class=\"wp-block-image\"><figure class=\"alignleft is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/i0.wp.com\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/55EDDF9B-DE42-4775-80F8-74DB9C5596D6.jpeg?fit=840%2C630&amp;ssl=1\" alt=\"\" class=\"wp-image-6514\" width=\"217\" height=\"163\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/55EDDF9B-DE42-4775-80F8-74DB9C5596D6.jpeg 4032w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/55EDDF9B-DE42-4775-80F8-74DB9C5596D6-150x113.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/55EDDF9B-DE42-4775-80F8-74DB9C5596D6-300x225.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/55EDDF9B-DE42-4775-80F8-74DB9C5596D6-768x576.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/55EDDF9B-DE42-4775-80F8-74DB9C5596D6-1038x779.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/55EDDF9B-DE42-4775-80F8-74DB9C5596D6-1200x900.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/55EDDF9B-DE42-4775-80F8-74DB9C5596D6-400x300.jpeg 400w\" sizes=\"auto, (max-width: 217px) 85vw, 217px\" \/><figcaption>Septic Snake works on his <i>McMeat<\/i><span>&nbsp;filter\/oscillator box. The xOxbOx and sound effector that you can hear on the self-titled <a href=\"https:\/\/soundcloud.com\/joshua-ac-newman\/sets\/def-sensor\">Def Sensor<\/a> on are just out of frame.<\/span><\/figcaption><\/figure><\/div>\n\n\n\n<p>Another interesting characteristic turned out to be that phototransistors are really sensitive. At first, I only had the tiniest bit of play \u2014&nbsp;I\u2019d send ~3.3V down the cable, which produced a dim light, which was what I expected. But then the receiver would hit 100% output <i>way<\/i><span>&nbsp;before the LED was at maximum brightness (which to be fair, is too bright to really look at)<\/span>. To keep the 9V signal (chosen in order to work with my creative partner Septic Snake\u2019s <a href=\"https:\/\/www.google.com\/search?q=xoxbox&amp;client=safari&amp;hl=en-us&amp;prmd=svin&amp;source=lnms&amp;tbm=isch&amp;sa=X&amp;ved=2ahUKEwjsnoyhy7LiAhUQc98KHYsmCZMQ_AUoA3oECAwQAw&amp;biw=1024&amp;bih=666\">xOxbOX<\/a>) from clipping, I started with a 330\u03a9 resistor \u2014 but then had to keep adding resistance to the output until I got to an incredible 1.5M\u03a9. The LED at the end of the S16 cable was visible, if dim, but at that brightness (encased as it was by a LEGO technic pin connector and only a couple of millimeters from the receiver), I got a really smooth transition from the forward voltage of the LED (3.3V) up through max voltage (9V). A lower voltage like 5V probably requires about 833\u03a9, but see the Forward Voltage issue below.<\/p>\n\n\n\n<p>Another exciting discovery was that the phototransistors I have respond reasonably well to all visible wavelengths of light, which means that you can send any color LED into it, and, while the response curve will be different for different colors, they will all induce a response as long as they\u2019re bright enough.<\/p>\n\n\n\n<p>This is what we call <i>very&nbsp;interesting<\/i><span>. It means on the one hand that the same signal coming down the cable will make different waveforms if the cable has a differently colored LED at the end. This is the kind of experimentation I want to encourage.<\/span><\/p>\n\n\n\n<p>On the other hand, it also means that white light gives a very even response because it spans the wavelengths \u2014 where it becomes less sensitive to red, it\u2019s already becoming more sensitive to green, and where it\u2019s becoming less sensitive to green, it\u2019s becoming more sensitive to blue. I don\u2019t know how it responds to infrared or ultraviolet.<\/p>\n\n\n\n<div class=\"wp-block-media-text alignwide\" style=\"grid-template-columns:10% auto\"><figure class=\"wp-block-media-text__media\"><img loading=\"lazy\" decoding=\"async\" width=\"500\" height=\"480\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/60B49FC0-28D4-4BB7-9C8C-6FACD0E48B77.png\" alt=\"\" class=\"wp-image-6521\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/60B49FC0-28D4-4BB7-9C8C-6FACD0E48B77.png 500w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/60B49FC0-28D4-4BB7-9C8C-6FACD0E48B77-150x144.png 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/60B49FC0-28D4-4BB7-9C8C-6FACD0E48B77-300x288.png 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/60B49FC0-28D4-4BB7-9C8C-6FACD0E48B77-400x384.png 400w\" sizes=\"auto, (max-width: 500px) 85vw, 500px\" \/><\/figure><div class=\"wp-block-media-text__content\">\n<p><a href=\"\/\/www.patreon.com\/Joshua\u201d\" target=\"\u201c_blank\u201d\" rel=\"noopener noreferrer\">Help me with my professional nerding by supporting my <i>xenoglyph<\/i><span> Patreon!<\/span><\/a><\/p>\n<\/div><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Transmitter\/Cable Forward Voltage<\/h2>\n\n\n\n<figure class=\"wp-block-gallery columns-2 is-cropped wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\"><ul class=\"blocks-gallery-grid\"><li class=\"blocks-gallery-item\"><figure><a href=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/9253DC0F-DE38-493F-9EC5-130C5E8FE1D0-1038x779.jpeg\"><img loading=\"lazy\" decoding=\"async\" width=\"1038\" height=\"779\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/9253DC0F-DE38-493F-9EC5-130C5E8FE1D0-1038x779.jpeg\" alt=\"\" data-id=\"6498\" data-link=\"https:\/\/glyphpress.com\/talk\/?attachment_id=6498\" class=\"wp-image-6498\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/9253DC0F-DE38-493F-9EC5-130C5E8FE1D0-1038x779.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/9253DC0F-DE38-493F-9EC5-130C5E8FE1D0-150x113.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/9253DC0F-DE38-493F-9EC5-130C5E8FE1D0-300x225.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/9253DC0F-DE38-493F-9EC5-130C5E8FE1D0-768x576.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/9253DC0F-DE38-493F-9EC5-130C5E8FE1D0-1200x900.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/9253DC0F-DE38-493F-9EC5-130C5E8FE1D0-400x300.jpeg 400w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><\/a><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><a href=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/EF617ACE-104A-4195-A1B2-DA32106DE933-1038x779.jpeg\"><img loading=\"lazy\" decoding=\"async\" width=\"1038\" height=\"779\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/EF617ACE-104A-4195-A1B2-DA32106DE933-1038x779.jpeg\" alt=\"\" data-id=\"6501\" data-link=\"https:\/\/glyphpress.com\/talk\/?attachment_id=6501\" class=\"wp-image-6501\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/EF617ACE-104A-4195-A1B2-DA32106DE933-1038x779.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/EF617ACE-104A-4195-A1B2-DA32106DE933-150x113.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/EF617ACE-104A-4195-A1B2-DA32106DE933-300x225.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/EF617ACE-104A-4195-A1B2-DA32106DE933-768x576.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/EF617ACE-104A-4195-A1B2-DA32106DE933-1200x900.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/EF617ACE-104A-4195-A1B2-DA32106DE933-400x300.jpeg 400w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><\/a><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><a href=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AAB28A50-90A3-4EC6-898C-6254087FD2AE-1038x779.jpeg\"><img loading=\"lazy\" decoding=\"async\" width=\"1038\" height=\"779\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AAB28A50-90A3-4EC6-898C-6254087FD2AE-1038x779.jpeg\" alt=\"\" data-id=\"6502\" data-link=\"https:\/\/glyphpress.com\/talk\/?attachment_id=6502\" class=\"wp-image-6502\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AAB28A50-90A3-4EC6-898C-6254087FD2AE-1038x779.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AAB28A50-90A3-4EC6-898C-6254087FD2AE-150x113.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AAB28A50-90A3-4EC6-898C-6254087FD2AE-300x225.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AAB28A50-90A3-4EC6-898C-6254087FD2AE-768x576.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AAB28A50-90A3-4EC6-898C-6254087FD2AE-1200x900.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/AAB28A50-90A3-4EC6-898C-6254087FD2AE-400x300.jpeg 400w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><\/a><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><a href=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E2A46C10-5C13-40C3-992D-B4EB904BC0D4-1038x779.jpeg\"><img loading=\"lazy\" decoding=\"async\" width=\"1038\" height=\"779\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E2A46C10-5C13-40C3-992D-B4EB904BC0D4-1038x779.jpeg\" alt=\"\" data-id=\"6500\" data-link=\"https:\/\/glyphpress.com\/talk\/?attachment_id=6500\" class=\"wp-image-6500\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E2A46C10-5C13-40C3-992D-B4EB904BC0D4-1038x779.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E2A46C10-5C13-40C3-992D-B4EB904BC0D4-150x113.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E2A46C10-5C13-40C3-992D-B4EB904BC0D4-300x225.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E2A46C10-5C13-40C3-992D-B4EB904BC0D4-768x576.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E2A46C10-5C13-40C3-992D-B4EB904BC0D4-1200x900.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/E2A46C10-5C13-40C3-992D-B4EB904BC0D4-400x300.jpeg 400w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><\/a><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><a href=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/00D44A8E-8D15-441C-B554-18C9638F52AE-1038x779.jpeg\"><img loading=\"lazy\" decoding=\"async\" width=\"1038\" height=\"779\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/00D44A8E-8D15-441C-B554-18C9638F52AE-1038x779.jpeg\" alt=\"\" data-id=\"6503\" data-link=\"https:\/\/glyphpress.com\/talk\/?attachment_id=6503\" class=\"wp-image-6503\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/00D44A8E-8D15-441C-B554-18C9638F52AE-1038x779.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/00D44A8E-8D15-441C-B554-18C9638F52AE-150x113.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/00D44A8E-8D15-441C-B554-18C9638F52AE-300x225.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/00D44A8E-8D15-441C-B554-18C9638F52AE-768x576.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/00D44A8E-8D15-441C-B554-18C9638F52AE-1200x900.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/00D44A8E-8D15-441C-B554-18C9638F52AE-400x300.jpeg 400w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><\/a><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><a href=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/1A36BE01-0867-4925-9907-A25E14A34AF1-1038x779.jpeg\"><img loading=\"lazy\" decoding=\"async\" width=\"1038\" height=\"779\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/1A36BE01-0867-4925-9907-A25E14A34AF1-1038x779.jpeg\" alt=\"\" data-id=\"6504\" data-link=\"https:\/\/glyphpress.com\/talk\/?attachment_id=6504\" class=\"wp-image-6504\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/1A36BE01-0867-4925-9907-A25E14A34AF1-1038x779.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/1A36BE01-0867-4925-9907-A25E14A34AF1-150x113.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/1A36BE01-0867-4925-9907-A25E14A34AF1-300x225.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/1A36BE01-0867-4925-9907-A25E14A34AF1-768x576.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/1A36BE01-0867-4925-9907-A25E14A34AF1-1200x900.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/1A36BE01-0867-4925-9907-A25E14A34AF1-400x300.jpeg 400w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><\/a><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><a href=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/D9A5B1D6-2A35-484C-AEBA-D2A1528E6A31-1038x779.jpeg\"><img loading=\"lazy\" decoding=\"async\" width=\"1038\" height=\"779\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/D9A5B1D6-2A35-484C-AEBA-D2A1528E6A31-1038x779.jpeg\" alt=\"\" data-id=\"6505\" data-link=\"https:\/\/glyphpress.com\/talk\/?attachment_id=6505\" class=\"wp-image-6505\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/D9A5B1D6-2A35-484C-AEBA-D2A1528E6A31-1038x779.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/D9A5B1D6-2A35-484C-AEBA-D2A1528E6A31-150x113.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/D9A5B1D6-2A35-484C-AEBA-D2A1528E6A31-300x225.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/D9A5B1D6-2A35-484C-AEBA-D2A1528E6A31-768x576.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/D9A5B1D6-2A35-484C-AEBA-D2A1528E6A31-1200x900.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/D9A5B1D6-2A35-484C-AEBA-D2A1528E6A31-400x300.jpeg 400w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><\/a><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><a href=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/A42818D5-23C3-4D98-A8A6-7022872C24D0-1038x779.jpeg\"><img loading=\"lazy\" decoding=\"async\" width=\"1038\" height=\"779\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/A42818D5-23C3-4D98-A8A6-7022872C24D0-1038x779.jpeg\" alt=\"\" data-id=\"6507\" data-link=\"https:\/\/glyphpress.com\/talk\/?attachment_id=6507\" class=\"wp-image-6507\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/A42818D5-23C3-4D98-A8A6-7022872C24D0-1038x779.jpeg 1038w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/A42818D5-23C3-4D98-A8A6-7022872C24D0-150x113.jpeg 150w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/A42818D5-23C3-4D98-A8A6-7022872C24D0-300x225.jpeg 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/A42818D5-23C3-4D98-A8A6-7022872C24D0-768x576.jpeg 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/A42818D5-23C3-4D98-A8A6-7022872C24D0-1200x900.jpeg 1200w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2019\/05\/A42818D5-23C3-4D98-A8A6-7022872C24D0-400x300.jpeg 400w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><\/a><\/figure><\/li><\/ul><\/figure>\n\n\n\n<p>An LED doesn\u2019t start to light (or even conduct electricity) until its power supply exceeds the \u201cbackpressure\u201d of voltage called <i>Forward&nbsp;Voltage<\/i><span>. That value is determined by the precise chemistry of the LED and the energy level of the light (which is determined unequivocally by General Relativity\u2014 this is a fundamental feature of LEDs that can\u2019t get better within our universe), which means there\u2019s some manufacturing variation in the precise color and therefore forward voltage, but in general, you can\u2019t light an infrared LED with less than 1.5V; or a red, yellow, or green LED without at least 1.8V; and a blue LED doesn\u2019t light until there\u2019s at least 3.3V behind it. White LEDs, which are actually blue LEDs with a yellow phosphorescent coating that respond to blue light, therefore also require at least 3.3V before they start to conduct, and therefore produce light.<\/span><\/p>\n\n\n\n<p>What this means is that, if my output is 5V and I\u2019m slowly turning it up from 0V to 5V, the output is 0 until the output reaches 3.3V, and then as I turn the voltage up to 5V, the LED only responds to the power increase from 3.3V to 5V. That\u2019s only 1.7V of the total range. It means that all control signals below 3.3V come out as 0, and higher level changes come out as between 0V and 1.7V. If you were to listen to an audio signal that did this, it would sound like the blown subwoofer in the back of a 1994 Celica from two blocks away as 67% of the signal gets lost to a speaker cone long ago drenched in Zima that keeps that cone from moving except under the strongest pressure.<\/p>\n\n\n\n<p>The first way I tried overcoming this was by using a <a href=\"https:\/\/www.allaboutcircuits.com\/textbook\/semiconductors\/chpt-8\/averager-summer-circuits\/\">voltage averager circuit<\/a> to make sure that 3.3V was always against the output and the output ran from 3.3V to 5V, which gave a full, smooth, linear output. But that defies one of the core design objectives of S16: that the transmitter does not need to be purpose-built \u2014 and, even worse, it\u2019s only appropriate for a blue or white LED. If I wanted to use a different color, the values would be wrong.<\/p>\n\n\n\n<p>My subsequent attempt, using an op-amp to accomplish the same thing (but additionally working for any forward voltage, (including 0V, which means it would work with a regular wire to another VC module), didn\u2019t work for no reason that I could discern even though it worked fine in my circuit simulator. And, in any event, still would require modification to the transmitter, so I bailed on that solution, though of course anyone who wants to implement it in their designs probably won\u2019t have the frustration I was having.<\/p>\n\n\n\n<p>My intention next is to forward bias the LED with an inline battery and run the voltage through it in series. With the low brightness of the LED, the current drain can be very low. Using three Size 13 hearing aid batteries would forward bias the LED with 4.2V. I\u2019m even thinking about putting a tiny 3.3V voltage regulator in there to make it give good signal for as long as possible.<\/p>\n\n\n\n<p>Of course, then you have a cable with batteries that can die.<\/p>\n\n\n\n<p>They don\u2019t call it Mad Science for nothing.<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img loading=\"lazy\" decoding=\"async\" width=\"1080\" height=\"209\" src=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2016\/08\/image.png\" alt=\"\" class=\"wp-image-3360\" srcset=\"https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2016\/08\/image.png 1080w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2016\/08\/image-300x58.png 300w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2016\/08\/image-768x149.png 768w, https:\/\/glyphpress.com\/talk\/wp-content\/uploads\/2016\/08\/image-1024x198.png 1024w\" sizes=\"auto, (max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px\" \/><figcaption class=\"wp-element-caption\">Modular systems are a function of industrial society. But do people of The Fifth World still know how to agree to standards? With their acute interest in efficiency, I think they might have carried that lesson forward!<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>The purpose of the S16 analog synthesizer communication network protocol is to make direct, machine-to-machine collaboration between experimental musicians safe and easy, guided by curiosity. Naturally, as I\u2019ve been refining and experimenting, I\u2019ve been finding ways to make it more difficult. But at least I don\u2019t think it\u2019s less safe.<\/p>\n","protected":false},"author":35,"featured_media":6519,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[192],"class_list":["post-6494","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-set-of-all-sets-that-do-not-include-themselves","tag-s16"],"_links":{"self":[{"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/posts\/6494","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/users\/35"}],"replies":[{"embeddable":true,"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/comments?post=6494"}],"version-history":[{"count":16,"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/posts\/6494\/revisions"}],"predecessor-version":[{"id":9100,"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/posts\/6494\/revisions\/9100"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/media\/6519"}],"wp:attachment":[{"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/media?parent=6494"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/categories?post=6494"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/glyphpress.com\/talk\/wp-json\/wp\/v2\/tags?post=6494"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}