[sdiy] Linearized 2164 VCA Warning

[David G. Dixon]

> If I read that correctly, you put an OP07 in the same socket?
> I assume you know that whereas the TL072 is a dual, the OP07 is a
> single, so completely different pinout.
> No surprise at all it got hot.

Ah!  Sorry, I misspoke (mistyped?).  I'm not actually that stupid (at least,
most of the time).  I checked my email archives, and it was in fact an
OPA2132 that I heated up.  I had a couple specimens lying around so I
replaced the TL072 with it based on Ian Fritz's suggestion.  He was as
surprised as I was that it heated up, as neither of us could see any reason
for it to do so based on my schematic, which (at least for that part) is
really quite ordinary.  Of course, the offset specs of the OPA2132 are not
that much more spectacular than a B-grade TL07X.

(Does this qualify as an "Emily Latella moment"?  If so, then "Nevermind!")

My misadventure with the OP-07 was something entirely different.  When I was
having such problems with my 2164 Expo VCO, I was seriously thinking about
using an ultra-low offset opamp to convert the 2164 expo current to a
voltage and then send this voltage into the saw integrator.  I did an
experiment with the OP-07, which has very low offset indeed, but the fact is
that there is no offset low enough for this particular application.
Ultimately, I found another solution.

Hey, they both start with OP!  :B