<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">I have researched this issue a bit.<div class="">A) I tried using a Digilent PMOD DA4 8-channel DAC. I got eight channels and only needed one set of SPI wires. Wicked fast.</div><div class="">B) I tried using PWM pins on the Teensy to drive "non-critical” (non-pitch-accurate) CV, example filter resonance and mixing the outputs of a state variable filter.</div><div class="">C) I looked into DAC boards with built-in wider voltage range. </div><div class=""><br class=""></div><div class="">A —> This thing is great but only gives me 0-2.5V range. It’s 12 bits, so I if double the output I get that reasonable range for 5 octaves of CV. (EIGHT OF THEM)</div><div class="">B —> This covers many use cases for CV. Teensy has lots of pins. I was able to automate all the knobs on a home-made drum synth with this approach.</div><div class="">C —> I purchased a break-out board for a Maxim Pixi chip. This crazy thing has 20 bidirectional DAC/ADC ports and you get a 0-10V range for free. I ran out of time this summer to explore this more.</div><div class=""><br class=""></div><div class="">My observations: </div><div class=""><br class=""></div><div class="">X) Modular synth folks tend to be “purists”, and most of the time I am not a purist. I don’t mind using CV that’s not pitch perfect if I am not trying to control something that does not emit a musical pitch.</div><div class="">I’m not heavy into that laboratory-grade normalization scheme. Not at this time, anyway. </div><div class="">Y) People are selling MIDI-to-CV products that use PWM. (Example: <a href="https://www.tindie.com/products/Robertron2084/midi-to-cv-converter-kit-midimuso-cv12/" class="">https://www.tindie.com/products/Robertron2084/midi-to-cv-converter-kit-midimuso-cv12/</a> )</div><div class="">Z) There ain’t nothing wrong with buying a break-out board for $60 if it saves me hundreds of hours of R&D and micro-soldering. </div><div class=""><br class=""></div><div class="">Other MIDI/Audio boards are competing with Teensy (<a href="http://www.axoloti.com/product/axoloti-core/" class="">http://www.axoloti.com/product/axoloti-core/</a> , <a href="https://www.electro-smith.com/daisy" class="">https://www.electro-smith.com/daisy</a> ) and they’re both 5V on the outside but a tender 3.3V on the inside.</div><div class="">In a year we’re all just going to get over the limited V/Octave range of the Teensy. </div><div class=""><br class=""></div><div class="">Bes wishes,</div><div class=""><br class=""></div><div class="">Ben</div><div class=""><div class=""><br class=""></div><div class=""><div class=""><div class="">
<div style="color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-east-asian: normal; font-variant-position: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-east-asian: normal; font-variant-position: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-east-asian: normal; font-variant-position: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-east-asian: normal; font-variant-position: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Benjamin Tremblay</div><div class=""><a href="mailto:btremblay@me.com" class="">btremblay@me.com</a></div><div class="">330 Fiske Street</div><div class="">Carlisle, MA 01741</div><div class=""><span style="color: rgb(51, 51, 51); font-family: Arial; line-height: 15.600000381469727px; white-space: nowrap; background-color: rgb(255, 255, 255);" class="">978-831-8315</span></div><div class=""><a href="http://www.linkedin.com/in/bentremblay" class="">http://www.linkedin.com/in/bentremblay</a></div></div></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"><br class="Apple-interchange-newline">
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<div><br class=""><blockquote type="cite" class=""><div class="">On Sep 16, 2020, at 5:29 AM, Spiros Makris <<a href="mailto:spirosmakris92@gmail.com" class="">spirosmakris92@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="">Hello list,</div>I am working on a (predominantly) midi project, based around the Teensy platform, and I'm trying to figure out the best way of adding a CV output, compatible (and useful) with eurorack.<div class="">Without any additions, I can use any off the shelf DAC to get 4 or 5 octaves of 1V/oct, but I would be interested in supporting the whole MIDI range (~10 octaves) - which means I need some switching converters, perhaps even a voltage inverter.</div><div class="">The options I can think of are:</div><div class="">1. Don't do anything, have 5 octaves of range.</div><div class="">2. Use a boost converter to get a 12V rail, then have 0-10V range</div><div class="">3. Use both a boost and inverting converter, to get a pair of dual voltage rails (-12/+12 or similar?), and use a (-3,8V) range.</div><div class=""><br class=""></div><div class="">I know the basic concepts of switching converters, but have never used one myself. I assume I need less than 100mA of current (to supply 4 opamps and a DAC), what parts would you recommend? </div><div class=""><br class=""></div><div class="">Regards,</div><div class="">Spiros</div><div class=""></div></div>
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