[sdiy] Using audio to trigger CMOS

[Justin Owen]

Thanks to everyone that's chipped in on this - much appreciated.

I think the first - and maybe the biggest - problem is getting enough gain from the input signal. I was hoping to get this running on a 9 volt single supply - and it seems like the most I've been able to coax out of an op-amp configured as an AC Coupled inverting gain stage is just under 1 volt of gain - so basically 0.01 volts at Note Off and just under 1 volt at Note On.

I did look at some Envelope Follower schems (and the Polyfusion schem has given me some clues) - but I was hoping for something alot simpler as this really just needs to convert a particular type of audio signal into a gate/trigger. (Although maybe I've underestimated how simple this should be...)

Roy and Anthony's suggestion about using a Hex Inverter in Linear mode is cool - will try that and see what goes.

Paul - Your suggestion about using a 555 one shot was also v. helpful - but it would mean re-jigging the way I have the rest of the clock set up - so at the moment, I'd like to try and solve this current set of problems. Always good to have a Plan B.

Harry - Yeah, Ideally I'm looking to get Note On and Note Off (pitch doesn't matter - it's the timing/on/off part I need)

Since I'm still a little stumped on this - any more input would surely be welcomed.

Thanks again to those who've helped out.

J