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What is the purpose of R1 in this circuit?


New Member
Could someone please walk me through the math of how R1 fits into the the final output voltage? Without it, my simulation produces a lot of noise and oscillations.



Well-Known Member
Most Helpful Member
As I suggested and Ronsimpson said in answer to your previous question, you need a series resistor connected to the opamp output.

You should never connect an op amp output directly to a capacitive load without a series resistor.

Until you have a resistor there, the results will be unpredictable.

ps. The resistor values you are using are all rather low for the majority of opamps, you should increase then by a factor of five or ten.

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