[sdiy] Need one of two things....

[Pete Hartman]

1) Is there anyone with experience or a pointer to a description of how the
Serge '73 R7 envelope generator works?  Basic googling gets me various
summaries of Ken Stone's page where "a little on how it works" is just the
schematic.  Got that, don't grok it in the slightest...

...Because I don't really "get" Norton Amplifiers.  (I have been able to
repair VCS' in the past but leaned very heavily on Tim Stinchcombe's
description of how it worked).  I mean yes, I understand logically "current
differencing" but in practical uses I can't look at a topology and say "oh
yes, this is an inverter/summer with gain X" the way I can with a standard
Op Amp.

So

2) out of all of the various circuit simulation tools that have been
discussed, which one or ones has a decent Norton Amp simulation?
Simulation is usually my go to with circuits that don't follow "standard"
often used topologies (standard like an expo converter, or
integrator/differentiator, etc).  I'm one of those who has long leaned on
the Falstad javascript simulator, and they do NOT have a Norton Amp (at
least not as far as I could tell, no promises that I didn't miss something).


I've got one of ZThee's 73-75 panels and none of the three EGs will cycle
in the usual way.  Power looks good, components have not been 100% verified
but everything I've checked directly against the circuit appears to be
correct.  Nothing is hot.  Soldering is solid (I resoldered a few joints
here and there, but mostly out of an abundance of caution).  None of the
usual first step troubleshooting methods has borne fruit so I'm now into
"ok I have to understand the circuit well enough to know what each bit of
it SHOULD be doing when I have end connected to start or cycle."

Thanks!

Pete
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