Op-amp circuits worksheet with answers

Free printable Op-amp circuits worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
−+Vout​3.5 VRs​ = 47 kΩRL​0.47 kΩIL​

A sensor behaves like a 3.5 V source with an internal resistance Rs = 47 kΩ. It feeds a load RL = 0.47 kΩ through an ideal voltage follower (unity-gain buffer). Find the load current IL supplied by the op-amp output.

Vs = 3.5 VRs = 47 kΩRL = 0.47 kΩ
IL = mA
2.Easy
−+Vout​10 VRs​ = 1 kΩRL​1 kΩ

A sensor behaves like a 10 V source with an internal resistance Rs = 1 kΩ. It feeds a load RL = 1 kΩ through an ideal voltage follower (unity-gain buffer). For comparison, find the load voltage VL if the load were connected directly to the sensor without the buffer.

Vs = 10 VRs = 1 kΩRL = 1 kΩ
VL = V
3.Medium
−+Vout​Rf​ = 22 kΩR1​ = 2 kΩVin​ = −2 VRa​ = 47 kΩRb​ = 1 kΩ

The op-amp is ideal and runs from ±15 V supplies. Find the output voltage Vout.

Vin = −2 VRa = 47 kΩRb = 1 kΩR1 = 2 kΩRf = 22 kΩ
Vout = V
4.Medium
−+Vout​R2​ = 2 kΩV1​ = 2.7 VR1​ = 1 kΩV2​ = 1.4 VR3​ = 1 kΩR4​ = 2 kΩ

The difference amplifier uses an ideal op-amp with ±15 V supplies, with R3 = R1 and R4 = R2. Find the voltage V− at the inverting input.

V1 = 2.7 VV2 = 1.4 VR1 = R3 = 1 kΩR2 = R4 = 2 kΩ
V− = V
5.Hard
−+Vout​C = 0.47 µFVin​ = 2 VR = 47 kΩ

The integrator uses an ideal op-amp with ±15 V supplies; its output saturates at ±12 V. The capacitor is uncharged when a constant input Vin = 2 V is applied at t = 0. How long after t = 0 does the output reach saturation? Find t.

Vin = 2 VR = 47 kΩC = 0.47 µFVsat = ±12 V
t = ms
6.Hard
−+Vout​Rf​ = 10 kΩV1​ = −0.2 VR1​ = 22 kΩV2​ = −0.7 VR2​ = 10 kΩIf​

The summing amplifier uses an ideal op-amp with ±15 V supplies. Find the current If through the feedback resistor, flowing towards the output.

V1 = −0.2 VV2 = −0.7 VR1 = 22 kΩR2 = 10 kΩRf = 10 kΩ
If = mA

Answer key

  1. 1. IL = 7.447 mA
  2. 2. VL = 5 V
  3. 3. Vout = −0.5 V
  4. 4. V− = 0.9333 V
  5. 5. t = 132.5 ms
  6. 6. If = −0.07909 mA

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