Serge Waveshaper schemos on Music Machines

Dan Higdon hdan at charybdis.com
Fri Jul 17 00:28:16 CEST 1998


From: Jim Johnson <jamos at technotoys.com>
>1) Which waveshaper is it? It looks closest to #2 based on the number of
>ins and outs, but it's not a perfect match.

I don't know - I haven't breadboarded this one yet, either.  The LM3900
is a quad, so I'd guess it's the other waveshaper - the one with multiple
identical sections (dang - I don't have my Serge catalog handy).  Maybe
a VC wave->square converter?

>2) Anyone know which input is which?

Nope.

>3) What's the polarity of the op-amp - which terminal is +?

3rd strike - but I'm not quite out yet.  :-)

>4) Why use an LM3900 in this circuit, rather than a TL-074? 

That one I *do* know - the LM3900 is a "Norton Amplifier", and as
such has some magical properties.  :-)  Seriously, the circuit only
works *because* it's an LM3900.  Mr. Serge patented a couple
of designs based on this chip.  If you look at the data sheet for it,
you'll also notice the Serge VC pulse divider.

----------------------------------------
hdan at charybdis.com
"Trust not the monkey, nor his clever schemes" - hdan




More information about the Synth-diy mailing list