[sdiy] 4069 VCO

[Pat Kammerer]

Well, I just finished the main section of Scott's modified 4069 VCO.  I must
say that it seems really nice for its simplicity, and the PWM sounds really
good.

There seems to be one issue with it right now, though, and I'm not sure
where to start for troubleshooting.  I double and triple checked my
connections, and everything seems right.   The problem is that when the
circuit is powered up, it works good, and the pitch seems okay, like maybe a
couple of KHz.  It stays that way for a minute or so, and then slowly drops
until it's about 30Hz or so. If you have tune set lower, it drops faster.
The only way to bring it back up is to turn the power on and then off again.
Has anyone had this problem, or can anyone help me understand what might be
going on there?  The same thing happened when I applied an external CV as
well.

All in all a really fun circuit though.  The waveforms look pretty good on
the Oscope too.

Thank you to all of you for helping me get this far!
Pat