How about one op-amp and 3 resistors?? The input goes to a 100K
resistor (R1) and one end of a 100K pot. The output of the op-amp is
connected to the the other end of the pot and another 100K resistor
(R2). The other end of R2 is coonected to the inverting input of the
amp and the other end of R1. The non-inverting input of the op-amp
is connect to ground. The input of the next next stage (the output
of your reversing attenuator) is connected to the wiper of the pot
with a 49.9K resistor (R3). Do I win?? :)
If the pot has a centertap to ground, it would need to be connected
with small resistor. You could build it on a MUUB or CGS
mixer/inverter PCB.
On 7/9/08, Scott Deyo put forth:
>
>The SEM VCF uses just one op-amp and four resistors, the pot having
>the CV straight to one side of the pot, the inverted CV to the
>other. Maybe a buffer on the output would be good, but that's still
>pretty darn tiny. NanoPolarizer?
>Doesn't Peter Grenader's Gizmotron do that, though?
>Are those still available?