I've seen schematics with polarised coupling capacitor at the output of op amps. Is the reasoning that the offsets are so small that it doesn't matter if the cap is the wrong way round?
There doesn't seem to be a way to predict the polarity of the offset voltages (at least not with the FET input op amps I'm using).
There doesn't seem to be a way to predict the polarity of the offset voltages (at least not with the FET input op amps I'm using).
A bipolar type works fine for this purpose, and will be fail safe if a problem results in high DC out.
Such as Nichicon Muse audio bipolar caps: (UES series) eg.
UES0J102MHM Nichicon Aluminium Electrolytic Capacitors - Radial Leaded | Mouser Europe
Before soldering polarised cap at the output of opamp I usually measure offset. If it is positive you solder positive side of cap to output and other side is properly polarised with resistor to ground, which is always there. If offset is negative you solder negative side of cap to output. That way you can use small footprint polarised cap without any concern.
You can see in Japanese amps many polarized caps between stages and I got the impression that their opamps are made in such way that have small offset but always with the same polarity so they dont have to measure anything and they know how to orient cap.
You can see in Japanese amps many polarized caps between stages and I got the impression that their opamps are made in such way that have small offset but always with the same polarity so they dont have to measure anything and they know how to orient cap.
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