Touch Kbds

[Dan Higdon]

Yeah, I have this book.  It's kinda interesting.  The thing I didn't like about it
was that Mr. Thomas decided to go with a very non-standard, wacky control
voltage scheme.  He uses 0 to 15v linear (V/Hz) controls for everything.  Granted, he
does give an exponentiator schematic near the back of the book, but all of
his modules seem to be linear.

I have built (proto only) his resonant filter (4 pole, BP), and it works ok
(linear CV response, natch), and his sequencer seems to work as well, though
I haven't tried to build out a whole sequencer yet, just a proto of the LED flashing
part. :-)  Oh yeah, and I proto-ed the VCO as well, and it works just fine for
a linear-control VCO, although I didn't really hammer on it since I don't have
a linear-control keyboard. :-(

If you don't mind doing a little extra design, the schematics look fairly sound
and simple.  After studying transistor design a little (he does almost everything
with trasistors and special purpose ICs, not opamps), some of his designs seem
a little screwy, but I admit I'm no electrical engineer. :-)

Because of the v/hz control, I haven't built any Thomas designs fully, because Wally
is working from 0-5 v/octave controls, and "he" won't talk to other standards happily.

Later,
Dan Higdon (hdan at charybdis.com)

----------
From: 	Joe Farler[SMTP:joef at roland.co.uk]
Sent: 	Friday, May 31, 1996 9:27 AM
To: 	synth-diy at horus.sara.nl
Subject: 	Touch Kbds

Just to let the list know that there is a design for a simple touch keyboard in
a book I recently borrowed.  There are also some other interesting synth
circuits. Here's the info:

"Sound Synthesis - Analog and Digital Techniques" by Terence Thomas

First published 1990 by TAB books.   ISBN 0-8306-9276-2 ( hardback )
                                       or 0-8306-   9276-x ( pbk )

Has anyone out there built any of the circuits in this book?
-- 
Joe Farler
joef at roland.co.uk