[sdiy] Singin' the S&H blues...

[Tim Ressel]

Yo,

Play me a durge, matie ... I be tellin' a tale of
sample and holds.

Yes, the drama is required. Silly me, I thought an
LM324 would be okay for a sample and hold buffer. It
looked good on the scope. Sadly, ears are very
sensitive to tiny little changes in pitch. So when my
okay-looking s&h output was tied to my VCO, well, it
was not good.

A quick look-see at the datasheets tells the tale: The
LM324 has worse-case 100nA of input bias current. The
TL074 is about 500 times better at 200pA input bias
current. Luckily, the pinout is the same.

So tomorrow I will try it and see if it fixes the
problem.

Sigh...

--Tim



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