[sdiy] LF398 and droop

[Veronica Merryfield]

I wouldn't use ceramic. Check out http://www2.naic.edu/~sulzer/cerCplots.pdf
Ceramics are ideal for high frequency bypass filtering and such. They also 
exhibit a voltage dependency characteristic. They aren' known for being low 
leakage either.

You need to be using a high performance, high precision, low leakage 
capacitors such as polypropylene or polystyrene.

The LF398 data sheet talks about a few dielectic types and has some other 
good info in it - http://www.national.com/pf/LF/LF398.html and click on the 
PDF link.

But in short, I am sure a ceramic capacitor is significantly responsible for 
your observed droop.

----- Original Message ----- 
From: mark verbos
To: Synth DIY
Sent: Wednesday, May 16, 2007 10:33 PM
Subject: [sdiy] LF398 and droop


How bad will a S&H build from an LF398 perform if a ceramic cap is
used? I built one using a .01 ceramic and I can actually watch the
voltage falling on the output. Is this the cap type? Am I missing
something?

Thanks,




Mark


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