asm1-VCO DRIFT!!

[Tony Clark]

> > i have  implanted my own build
> > regulator i (7815/7915) and i have notice this new disturbinese in 
> > the force every pot. that has + to - 15 range
> > such as the FC (filter section) pot , or pwm pot. causes the vco to drift
> > slightly while tweaking.
> > when the turn reaches the limit suddenly a small shift in the osc, is heared.
> > i scoped it , the change is measured like 30 to 40 mv shift.
> > (checking the coarse tune middle leg)

   Welcome to the fun world of building synths!  This kind of problem I 
have found to be quite common, even with good regulated linears.  This is 
why I never run much (if anything) from the supply rails but instead build 
stable voltage references (note:  _references_ and not _regulators_) for 
which to drive pots.  It also eliminates supply line signals/noise, which 
I find to be another annoyance.
   Done properly and your synth will not drift even if the supply line 
should vary by a few _volts_!

   Good luck!

   Tony

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