Op-amp circuit question.

[Merc]

Can someone tell me what the purpose of the circled RC network is? I'm guessing it would slow the feedback response.

[Jerry]

It is part of a bandpass filter. Check out the TGSL diagram, and you will find that U103 is the same circuit but with different component values. Most Tesoro circuits I have seen have similar filter sections.

Jerry

[Carl-NC]

True, it's a high-pass filter, and passes frequencies above about 7.2Hz. R16|C9 form the low-pass portion, with a cut-off of 7.2Hz. So the overall response is a very narrow bandpass.

[Merc]

It makes sense to me now. I looked online for similar circuits, but didn't really find anything similar. I'm guessing that needing a bandpass centered around 7 Hz is unique to this field.

Thanks,
Merc

[Carl-NC]

This is the post-demod filter, where the signal "frequency" is due to the sweep of the coil, which is relatively slow. 7Hz is a pretty decent setting for an average swing rate. You could eliminate the high-pass portion (C10) if you wanted zero-motion response, at the expense of greater noise.