Moog 904A lowpass filter Question

[jh.]

> BTW, does anyone know for sure it is OK to leave the substrate connected
> transistor (pins 13,12, and 14) floating rather than hard wiring pin 13 to
> v- ?  In that case it would seem to me that diode action with the other
> transistors would bring the substrate at least as negative as any other
> transistor.

I don't remember in which circuit, but I'm quite sure that ARP were so
bold (and probably so experienced) that they even broke the rule
of pin 13 being the most negative of the array. In that circuit pin 13
was slightly more positive than the emitter of another transistor of the
array, but not so much more positive that a significant current would
be drawn. Joachim, maybe you remember that circuit ? I only remember
that we talked about that ...

As for ARP's "Moog" filter, maybe the extra diodes were just in there
to confuse patent lawyers ? Might be worth a thought, given the situation
at the time ...

JH.

(just back from Poland, switching 20 MegaWatts at 110kVolts, so
expect a confused mind being directed to microAmperes again (;->) )