moog hp

[tomg]

> From: Osamu Hoshuyama 
> Schematics of Moog HPF is included in Moog Modular at E-MUSIC DIY
> ARCHIVE.
> 
> http://aupe.phys.andrews.edu/diy_archive/manuals/moog/modular/
> 
> The redrawn schematic (mod_19a.gif) has an error around buffer amp
> using NPN and PNP transistors.  Collector of PNP transistor should be
> connected to the emitter of NPN transistor for current feedback.
> Dots which indicate connection are missing.

> > >Could you explain how close, without having to write a novel. 
> > >I would like to know how close I came.
> > >tg

> > I remember I've seen the Moog HP somewhere 
> > JH.

Thanks Osamu...
Yeah...Right! Like I thought I was gona be close or something. I'm not
even in the same universe.... If I had tried this from the schematic I
would
still be working on it. It's almost unbelievable that my version works at
all.

It helped thought. I put 1Ks on all the pnp collectors and 2.2Ks on all the
npn collectors, changed the 10K common base resistors to 100 ohms.

This increased the range a little. With the res at 100% it now oscillates
from 0 to about 75% frequency.

Heres a new sample ( my usual crap way of holding the mic over my
bench amp ) the fist part is a on the edge sweep with audio breaking
into oscillation right at the bottom and the second part is a no audio
sweep at max res.

The reason I explain this is hi-pass filters examples are really hard
to sample if you're going to cut them down in size

So the new sample comes in two flavors big and crappy or smaller 
and worse. It's the same sample... only here for a short time.

Big - 525K
http://www.mindspring.com/~vco/cbook/pics/moog_hp2.wav

Small - 191K

http://www.mindspring.com/~vco/cbook/pics/moog_hp3.wav

-tg