In this problem, the OP-AMP saturates at 10 V. For t < 0, with the switch open, the circuit is operating in the steady state. If the switch closes at t = 0:
1. What is v(0+)? (Notice that v is the voltage drop in the capacitor.)
2. What is the slope of v(t) at t = 0+?
3. What is the time constant of the circuit for t > 0?
4. Find v(t) for t > 0.
5. Sketch and label v(t) for all t > 0.
6. Sketch and label the current through the diode for all t > 0. Assume there is a 1 V voltage drop in the diode when it is ON.
7. Find the time instant at which the diode turns on.
+10 V
7 kΩ
+10 V
10 kΩ
200 Ω
1F
10 kΩ