Diodes & transistors worksheet with answers

Free printable Diodes & transistors 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
+−Vs​10 VR = 680 ΩD1​D2​I = ?

A 10 V DC source drives current through a 680 Ω resistor in series with two forward-biased silicon diodes. Use the constant-drop model with 0.7 V per conducting diode. Find the current I in mA.

Vs = 10 VR = 680 ΩVD = 0.7 V
I = mA
2.Easy
+−24 V470 Ω5.1 VIR​ = ?

A 5.1 V Zener diode is fed from 24 V through a 470 Ω resistor, with no load connected. Find the current IR in the resistor.

Vin = 24 VVZ = 5.1 VR = 470 Ω
IR = mA
3.Medium
+−15 V270 Ω6.2 V3300 ΩIZ​ = ?

A 6.2 V Zener regulator is fed from 15 V through 270 Ω and supplies a 3300 Ω load. Find the Zener current IZ.

Vin = 15 VVZ = 6.2 VR = 270 ΩRL = 3300 Ω
IZ = mA
4.Medium
+−24 V680 Ω9.1 V1500 ΩIZ​ = ?

A 9.1 V Zener regulator is fed from 24 V through 680 Ω and supplies a 1500 Ω load. Find the Zener current IZ.

Vin = 24 VVZ = 9.1 VR = 680 ΩRL = 1500 Ω
IZ = mA
5.Hard
+−≤ 21 V470 Ω3.3 V

A 3.3 V Zener regulator has a 470 Ω series resistor. The input can rise to 21 V, and the load may be disconnected. Find the largest power PZ,max the Zener must dissipate.

Vin,max = 21 VVZ = 3.3 VR = 470 Ω
PZ,max = mW
6.Hard
RC​ = 680 Ωβ = 150IC​ = ?VCC​ = 12 V3.3 VRB​ = 10 kΩ

An NPN transistor with β = 150 switches a 680 Ω load resistor connected between VCC = 12 V and its collector. The emitter is grounded. The base is driven from a 3.3 V logic output through a base resistor RB = 10 kΩ. Take VBE = 0.7 V and VCE(sat) = 0.2 V. Find the collector current IC in mA when the input is high. Decide first whether the transistor is saturated.

VCC = 12 VRC = 680 Ωβ = 150Vin = 3.3 VVBE = 0.7 VVCE(sat) = 0.2 VRB = 10 kΩ
IC = mA

Answer key

  1. 1. I = 12.65 mA
  2. 2. IR = 40.21 mA
  3. 3. IZ = 30.71 mA
  4. 4. IZ = 15.85 mA
  5. 5. PZ,max = 124.3 mW
  6. 6. IC = 17.35 mA

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