What is the purpose of R1 in this circuit?

[stryker12]

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.

 

[rjenkinsgb]

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.

 

[Beau Schwabe]

Look up "summation" or "summing" amplifier. This does look like homework though