[sdiy] Problems with linearized SSI2164 ?

Neil Johnson neil.johnson71 at gmail.com
Thu Feb 7 23:16:54 CET 2019


Hi Danjel,

> I swapped the 22p for 100p and problems seemed to go away!

Yay!  Problem solved.  And only one component to rework instead of
three.  I would also suggest rolling out this change to all your
linearised VCA circuits, even those still using the V2164.

> I guess the v2164 was less sensitive to HF oscillations (or at least we were able to get away with 22p) but it is critical to have a larger cap with the ssi2164.

The capacitor tames the TL072 from oscillating, so I suspect (I have
no evidence either way) that the difference between the V2164 and the
newer SSI2164 is that the outputs of the SSI2164 are stiffer than that
of the older V2164.
I'd be curious to know why you chose to go with 22p compared to the
100p as given by both Irwin and Gallo?  Was it simply BOM
optimisation?

Cheers,
Neil
-- 
http://www.njohnson.co.uk


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