[sdiy] Welcome to the Twilight Zone

[Peter Grenader]

Thought I'd share a bit of bizarro behavior which occurred late last night.

When putzing around with the prototype Plan B (vector board) all of the
knobs except the PWM and FM attenuator - the Freq, fine tune, even the two
bipolar freq VC attenuators - suddenly operated in reverse.  Turning the
freq pot CCW made the pitch higher.  Turning a freq VC attenuation pots
fully CCW processed the VC fully positive (should be the other way around).

Turned the power off - still there.  repeated that a few times - still
there.  So then I put my VC Input through an external processor to invert in
before it went to the VCO to see if I could fake the VCO out and when
turning the offset knob on that processor in a  positive (more voltage)
direction, I suddenly noticed that the controls returned the 'normal'
operation on the VCO.

They are all running off the same supply.  However, in the name of science
and unparalleled universes, all of the effected controls do run through the
same op amp internally (they are summed).

Too weird and yes, I did check for flying donkeys outside and no, my cat did
not begin to bark during this time.

Now off sign to going I'm,


- P