Caps vs Inductors

[Harry Bissell]

Harry Bissell: We know that caps and inductors are basically inverse functions
of each other, but the perfect cap has infinite series resistance, the perfect
inductor has zero series resistance. Build a moog ladder with inductors and it
isn't a ladder anymore, its just 4 transistors. The npn-pnp with 4 caps is
perfectly reasonable. Why not use the state-variable configuration and be done
with it?

Heresy: I think highpass filters kind of suck anyway...    :-) Harry


Terry Michaels <104065.2340 at compuserve.com> wrote:
Message text written by Martin Czech
>Yes, as somebody pointed out, you have to replace the ladder rungs (which
are C in the Moog LP) with a resistive element and the trannys with Cs.
Doing this straight forward causes Problems, 8 Caps, and the resistive
element isn't differential any more, how to bias ? 
So the resistive element is split up into a PNP to one rail and a NPN
to another rail, and only 4 caps couple the resistive element knots. The
original moog modular schematics are on the web (music machines, I think).
<

Hi Martin:

Actually, there might be another way to make a high pass.  Replace the
capacitors in the Moog ladder array with inductors.  Never tried it myself,
though.

Terry Michaels


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