[sdiy] Using audio to trigger CMOS

[harrybissell at wowway.com]

Are you trying to trigger on a note event, or to divide a frequency?

If it is a frequency, check out any of the "octave pedal" schematics
such as Boss, Roland, DOD etc...  

H^) harry




On Mon, 28 Apr 2008 22:33:53 +1000, Paul Perry wrote
> A 555 timer rigged as a one-shot might be useful here.
> 
> paul perry Melbourne Australia
> 
> -----Original Message-----
> 
> I'm hoping for some help refining a circuit I'm working on that uses 
> an audio signal as a clock to trigger a 4024 Ripple Counter.
> 
> The audio signal is a 1/16th note sequence that is meant to 
> represent a square wave i.e. Note On = High (or Mark), Note Off = 
> Low (or Space).
> 
> I've got a prototype that uses an AC Coupled gain stage to take the audio
> input and feeds it into a comparator.
> 
> The current version works(ish) minus some problems which I think are 
> down to some ac coupling mistakes and a lack of headroom on my power 
> supply - all of which I think I can sort - but I was wondering if 
> there also needs to be any type of rectification between the gain 
> stage and the comparator?
> 
> I can be pretty specific about the type of audio signal that goes in 
> (I'm currently using a PWM square wave with a 90/10 mark/space ratio 
> at a fairly high pitch - which I figured would give the greatest 
> ratio of High to Low signal when the Note was 'on') - I'm not 
> expecting to get a square wave trigger out of a guitar input for 
> example - but I'd like the circuit to be as safe and reliable as possible.
> 
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Harry Bissell & Nora Abdullah 4eva