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

[Oren Leavitt]

On 10/30/20 8:42 PM, Pete Hartman wrote:
> Thanks Neil!
>
> Currently trying to absorb it.... :)
>
> Pete
>
Clone a PAiA Gnome - It'll give you a feel for how Norton op-amps work.


> On Fri, Oct 30, 2020 at 7:52 PM Neil Johnson <neil.johnson71 at gmail.com 
> <mailto:neil.johnson71 at gmail.com>> wrote:
>
>     Hi Pete,
>
>     TI's AN-72 is a pretty good read on how Norton op-amps work and many
>     applications, including all the "standard" circuit blocks:
>     https://www.ti.com/lit/pdf/snoa653
>     <https://www.ti.com/lit/pdf/snoa653>
>
>     Neil
>
>     On Sat, 31 Oct 2020 at 00:09, Pete Hartman <pete.hartman at gmail.com
>     <mailto:pete.hartman at gmail.com>> wrote:
>     >
>     > 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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