@Audioguru again @tautech et al. AG convinced me to prototype instead of breadboard, so I've been doing that but still getting some puzzling artifacts in the Bode Plot sometimes. That is the really strange part, it doesn't happen all the time. It seems that if I start cold the first pass is clean and then the successive passes pick up 2 artifacts. For example...
First pass @ low bandwidth
First pass @ higher bandwidth
Subsequent passes
I've been seeing this on other Bode Plots and assumed it was noise (still do) but not sure why I don't see it at all times. One artifact from 10-40Hz and another ~110-140Hz (60Hz harmonic? but nothing @ 60Hz). There is a very small blip @ 60Hz and would expect any harmonic to be less? Adding 1nF caps between V and GND and placing them on the op amp power pins makes no difference. I even twisted the power and GND cables from the PSUs with no difference noted. What is causing this artifact, and can it be controlled or eliminated?Would this somehow have to do with the capacitors charging minutely over time?
First pass @ low bandwidth
First pass @ higher bandwidth
Subsequent passes
I've been seeing this on other Bode Plots and assumed it was noise (still do) but not sure why I don't see it at all times. One artifact from 10-40Hz and another ~110-140Hz (60Hz harmonic? but nothing @ 60Hz). There is a very small blip @ 60Hz and would expect any harmonic to be less? Adding 1nF caps between V and GND and placing them on the op amp power pins makes no difference. I even twisted the power and GND cables from the PSUs with no difference noted. What is causing this artifact, and can it be controlled or eliminated?