[sdiy] Microphonics

[Roman]

Is whining somehow related to VCO frequency?  Do you have any DC/DC converter?  My first guess would be the largest ceramic cap you have there.  Or electrolytic capacitor run over maximum ripple specs.   Roman   Dnia 22 stycznia 2018 17:24 Tim Ressel <  timr at circuitabbey.com > napisał(a):  Got a weird one...   An oscillator I designed is whining. Well, some units do it. It is faint  and you have to have your ear right up against the board to hear it. But  an end user complained so we had to investigate. Other weirdness ensued  but we got the customer taken care of.   My question is: how to find where the whine is coming from? I tried  using a microphone but could not pick anything up. This is an ASM-1 type  VCO (saw core) so there is a pulse train present. That could explain the  mic not picking it up. I tried putting my finger over various components  on the board with no luck. I thought about using an accelerometer but it  would have to be high sensitivity and low mass to work.   I am at a loss.  Any thoughts?   --  --Tim Ressel  Circuit Abbey   timr at circuitabbey.com   ______________________________  Synth-diy mailing list   Synth-diy at synth-diy.org  synth-diy.org synth-diy.org
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