[sdiy] PWM from a Micro as a CV source?

[harrybissell at wowway.com]

The LPF after the PWM will limit how fast you can change the CV...
otoh its not likely to be slower than optocouplers anyway...

H^) harry




On Fri, 13 Jun 2008 12:34:08 +0000, Justin Owen wrote
> Hey all,
> 
> I'm after some advice on using PWM-capable pins from a Micro 
> (probably the ATMega168/Arduino, and possibly via a TLC5940 LED 
> driver) as a CV source.
> 
> The oscillator I'm using at the moment has its Pitch and PWM 
> controlled by two HF113 Optocouplers, each sitting in the negative 
> feedback loop an Op-Amp to make the control linear, which is fed a 
> control voltage - which at the moment is basically pots set up as 
> voltage dividers.
> 
> I'd like to replace the pot/voltage dividers with PWM outputs from a 
> Micro.
> 
> Are there any reasons why this shouldn't work?
> 
> Would I need a Low-Pass filter of some sort on the PWM output?
> 
> All the info I've seen says it will control LEDs just fine - so 
> therefore it should drive an Optocoupler - just wanted to see if 
> there were any problems I might not have thought of.
> 
> Thanks as always - J
> 
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Harry Bissell & Nora Abdullah 4eva