No triangle for me

So for some reason my 3340 oscillator build has no triangle out! The sawtooth is working, but not the triangle signal. Any possible ideas on this one?


which circuit have you built?


The simple 1v per octave

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If you have the other waveforms, then unless there’s something very weird wrong with your 3340, it’s putting out a triangle too, on pin 10. From there all that happens is it goes (via that long yellow jumper) into the TL072 which also presumably works, and then out. So the only reasonable possibilities are bad solder joints or layout errors on:

3340 pin 20 to long yellow jumper to TL072 pin 5
TL072 pin 7 to short yellow jumper to pin 6
TL072 pin 7 to yellow hookup wire to triangle out jack
ground connection to triangle out jack

Examine and re-flow those solder connections. Check that the layout is correct (looks right to me). Are the ICs socketed? Make sure they’re seated properly,

If there are still problems you can try swapping in new ICs (TL072 first, of course) but, again, given that other outputs work, it’s unlikely there’s an IC problem.


Oddly, only one of my CEM chips does this - I get no sound from any of the others at all.

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HAH! I found it. The 1.5M resistor was on the wrong trace! Now everything works!


Once you have one thing working, it makes life easier for everything else.

Maybee there is a need for a CEM/AS “Chip Tester” to check basic operation on them ( with ZIF sockets.


That’s pretty much what the simple 1 v/oct stripboard layout is, though :slight_smile: That circuit is about as minimal as you can make it.


Good thing. Its obviously taxing my abilities as now I have to figure out why I have no square wave XD

Once again, incorrect resistor value. I am certainly getting better at troubleshooting.