3340 osc makes weird stuff

Hey, I’m trying to build the 3340 Osscilator. It doesn’t work and i don’t understand whats going on. I’m a noob at building stuff, please help me^^
What i have found out so far:

  1. I only get sound from the saw out, the other ones stay quite. The pitch knob works but just between 4k-6k i’d guess, not the whole range.
  2. All outputs have -12 volt (I had in mind that standard be 5 volt, maybe its allready an fail? But the saw out is also -12)
  3. The trimpot changes nothing.
  4. The few volts on this picture match with my one (Annotated Simple 1V/Oct Oscillator Stripboard)

How do i troubleshoot the problem? I dont really understand the troubleshooting advice post, i guess beacuse i’m building the stripboard version.
thanks a lot


Hello Rufus and welcome to the forum.
Neither am I an expert but there are a lot of experienced people here who might be able to help. Could you post a picture of your build please?


I don’t understand your description, you say you have sound at saw out but you also say saw out is -12 V. These can’t both be correct. Are you using a scope or a multimeter? If you’re trying to measure voltage on the outputs with a multimeter you probably won’t get very useful results since these are not (supposed to be) constant voltages. Even so I would not expect it to show -12 V on an output that is producing sound.

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Hey, thanks:)
I dont have a phone with a camera, so it takes some time to upload a photo but i’ll try

Ok weirdly i’ve double checked it, now i dont have sound on the saw out anymore, but the -12 v stayed. I use a multimeter.
Hmm so probably i made a mistake while soldering or how could that be?

If you had sound then that would mean the 3340 chip is working, or was. If you have -12 V on the outputs that would suggest the output op amps have a problem, a bad connection or a solder bridge or something like that. If the sound was there and is gone now that sounds like an intermittent bad connection. Check around the op amps. Wiggle stuff and see if anything happens.


Welcome to the forum :slight_smile:
if it’s on stripboard, maybe pass a knife blade or other in the inter lines and / or check with a magnifying glass that there is no short circuit invisible to the eye.