Physics Help Forum Op Amp circuit and RC circuit transient analysis.

 Sep 6th 2017, 02:02 PM #2 Senior Member   Join Date: Nov 2013 Location: New Zealand Posts: 548 The first looks like a controlled gain circuit (So A shouldn't figure in final analysis). I think you should be able to solve that with Kirchoff's laws. https://en.wikipedia.org/wiki/Kirchh...s_circuit_laws. The voltage $\displaystyle V^{+} = V_{in}$ as there is no voltage drop across RS as no current is flowing through the inputs of the op amp. R1 and R2 comprise a voltage divider which you can work out the voltage drop between them from ohms law. That should give you V- and from there you should be able to calculate $\displaystyle V_{out}$ and the gain $\displaystyle \frac{V_{out}}{V_{in}}$. The second just looks like a capacitor resistance network. From google the current formula for a capacitor is $\displaystyle I = C \frac{dV}{dt}$. I would assume the two $\displaystyle V_{dd}$ points are connected, as they are at the same potential, even though they are not drawn that way. You should be able to solve this using Kirchoff's current laws. __________________ Burn those raisin muffins. Burn 'em all I say. Last edited by kiwiheretic; Sep 7th 2017 at 12:14 AM.