[sdiy] Genital Electric P/V converter LIVES

[harrybissell]

Sometime in the late 70's when young Harry Bissell was realizing he
would
never be a serious keyboard player... he dreamt of controlling his
modular
from his guitar. Now if only he could afford a Gentle Electric GE-101
Pitch to
Voltage converter, he could DO that. At that time they were distributed
by Serge
as a 'kit' (board set)... in fact the very set that I got. They were
obviously intended
for the Aries system originally, as they have the same outline and 22
pin edge
connector.

It was about $800 at that time... cost more than my entire modular AND
guitar.
Glad I didn't get one then, it would not have worked well enough.  It
does not have
any filtering, so octave hopping and pitch-to-glitch conversion is very
real possibility.

It does have all the right stuff. What I came up with on my own has
quite a lot of the
same features. They use a compressor, ride the largest peaks on positive
and negative
half cycles, square that up with the equivalent of an RS flip-flop. They
reset and sample hold a ramp (same as Roland, 360 systems,
Etherwave/Moog P/V, and my
own system)... check for valid range (if the ramp is too big, stop
sampling) and look for
subsequent samples to be within a certain range of the previous sample,
or again inhibit the S/H.  It also features linear and log amplitude
envelopes, gate, trigger, retrigger... all the standard features.

How it works on other instruments I have no idea ???

That about sums it up.  I always wanted that P/V converter. Now I have
it and can understand it as well. Like a kid who wanted a mini-bike, and
thirty years later realized
his dream by buying a Mercedes.  Who needs a mini-bike anyway.   :^P

The original designer, Carl Fravel is still around. I gave him Cynthia's
web address incase he wanted to release a 'Tribute' version.  He did
offer to reveal the contents
of the potted module in exchange for a non-disclosure agreement.  I
declined because I
had already RE'd the circuit... and am doing P/V work of my own. Don't
want to tie my own hands.   I'll give him some time to maybe
come-out-of-the-closet and make some
modules or kits for the diy crowd. Failing that I might do so myself.  I
think he needs
to either make some boards, or loose the design to the world. Just mho.
Maybe you guys should contact him and tell him to come out and play.
Analog synthesis LIVES.

H^) harry

Tim Ressel wrote:

> Way to go Harry!  Woo Hoo!  You da man!
>
> Just one thing: What the hell is a GE-101 PV
> converter?
>
> --TimR
>
> --- Harry Bissell Jr <harrybissell at prodigy.net> wrote:
>
> > My Gentle Electric GE-101 PV converter has come
> > back from the grave. I bought it "as is but in good
> > shape" from someone on AH. It was blown to kingdom
> > come, probably from reverse voltage on the power
> > supplies. I paid way too much for it in the
> > condition
> > received (but hey, it was 'as-is' right ???)
> >
> > My first clues to an amateur repair attempt was that
> > ALL THE ELECTROLYTIC caps were replaced, cheap
> > sockets
> > were inserted for all the opamps (also replaced).
> >
> > another clue. One IC had the non inverting input
> > drilled OFF CENTER to accomodate a guard ring
> > (common
> > S/H technique).  The person (dis)effecting the
> > repair
> > put in an IC socket with that pin 'folded under' so
> > no
> > connection was made. Were they going to hook it up
> > later, or did they just bone it ???  I think (from
> > the
> > mass capacitor destruction) the latter...
> >
> > Sad is that the potted modules (2) were blown out...
> > the fundamental extractor AND the expo module. Even
> > the 2K Q81 tempco was toast. All the cmos chips were
> > trashed, as well as a large number of transistors
> > and
> > diodes.
> >
> > Glad is that I was able to reverse engineer the
> > modules
> > with hammer, chisel, and propane torch.  I just
> > found
> > the last problem, which was a defective opamp that
> > still worked, but maybe had an extrememly LOW input
> > impedance due to internal damage.  Replaced it with,
> > yup... a 741 and it started working. OK so 741's
> > suck... but I'm fresh out of LM301s
> >
> > It was a lot of pain to fix this, but I wanted it
> > for
> > educational purposes. If it HAD worked, would I have
> > smashed the potted modules open ???  Probably not.
> > How well does it work ?  I'm not sure yet, but it
> > does
> > the P/V thing as advertised.
> >
> > Maybe when its in a box, I should send it to another
> > Gentle Electric owner for an A/B test ???   :^P
> >
> > Anyway... I just wanted everyone to know there is
> > life-after-talking-about-your-manhood on s-diy
> >
> > H^) harry
> >
>
>
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