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Zero Cool 15th September 2010 11:49 PM

Op-amp EQ Experts? Puzzle for you!
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Any op-amp RC filter experts here? Here is an interesting puzzle for you.

here is an op-amp based RC filter circuit. input is on P801 and output on P804 I understand the power and the bias arraignment. As they are running these opamps off a single ended +9v supply, I understand how the 1/2 supply voltage line works to bias the opamp half way between the rails so it can swing + and - that is understood.

This looks to be a 3 band notch filter...I think. can anyone tell me what the filter specifics are? freq, q, boost/cut amount etc?

Andrew Eckhardt 16th September 2010 12:46 AM

Oh that's a beauty. They make it extra easy to follow by drawing it with the actual pin orientation, as if that were more important than understanding the circuit. Looks as if the drawing is mainly for servicers. I'd help but I'm hardly an Op-amp EQ expert and I already got confused by the Right Left position at the connectors. I'll bet if you re-draw it you can make better sense of it. Draft it into ltspice and see! Those amp specs don't look super.

Leon08 16th September 2010 01:45 PM

If you want to know what this circuit does, then you can build it in some simulator and test it, but to calculate it is to much work.

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