8 Jun
2010
8 Jun
'10
3:13 p.m.
The stuff around 14 kHz in R is strange. It's
noise, not a
single frequency interference. No idea where it comes from.
Last time I saw a random peak that strong, it turned out to be a
byproduct from an opamp that was underdamped and self-oscillating at
about 10MHz... It moved around just a little bit as the oscillation
wasn't itself entirely stable. Complete shot in the dark, I do't
expect to ever see it again (except in homebrew designs that are
slapped together without alot of design analysis).
Ah, the fun of using sound cards as analyzers :-)
Monty