MOTM

I once opened up some later Serge modules with the intention of reverse
engineering them.  Saw lots of CA3280s but no 3900s, though this was in one
of the VCFs.  Didn't get far with the project, since the modules were very
tightly packed onto small pcbs and it wasn't my system to destroy.   
 

-----Original Message-----
From: jhaible@... [mailto:jhaible@...]
Sent: Monday, October 16, 2000 12:49 PM
To: motm@egroups.com
Subject: Re: [motm] Is this useful?



> I studied the LM3900 app notes a year or two ago, and came to the same
> conclusion about the Serge pulse divider.  I'm as sure as someone who has
> never seen the insides of a Serge module can be that it's using a purely
> analog LM3900 staircase generator to do the dividing.  And part of me
> respects the pure-analog-ness of that solution. ;-)

There is a chance that Serge started with a 3900 circuit and upgraded it
to something more involved later, of course.

My own pulse divider story goes like this: Read the Serge catalogue,
thought it was a cool feature, designed a mildly involved analogue
circuit with CMOS gates and opamps (also a charge pump design),
and discovered that National application note *later*.

BTW, I wonder how Serge's phaser looks like, just for the sake of
curiousity.
I've once built the circuit from his patent (also LM3900-based, big
surprise),
and the effect was very interesting but not quite what I expected from a
phaser.
As the Serge phaser has a reputation for being very clean (and what I built
from the patent disclosure is the very contrary), I'm sure he's added a lot
of extra circuitry, or has switched to a different concept later.

JH.