[sdiy] CV outputs from 3.3V and 5V uC systems

Tom Wiltshire tom at electricdruid.net
Wed Sep 16 12:57:36 CEST 2020

Why not just use an op-amp on the +/-12V rails to increase the output from the DAC from 3.3V or 5V or whatever you have? It’s only a little bit of gain you need. Of course, the steps between DAC values increase too, but that’s just a question of having enough resolution, which you’d need to do anyway, even with a higher voltage DAC.

Messing around with power supplies is overcomplicating it, it seems to me.


      Electric Druid
Synth & Stompbox DIY

> On 16 Sep 2020, at 10:29, Spiros Makris <spirosmakris92 at gmail.com> wrote:
> Hello list,
> 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.
> 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.
> The options I can think of are:
> 1. Don't do anything, have 5 octaves of range.
> 2. Use a boost converter to get a 12V rail, then have 0-10V range
> 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.
> 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? 
> Regards,
> Spiros
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