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.

New worksheetPractise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
+−20 V470 Ω9.1 VIR​ = ?

A 9.1 V Zener diode is fed from 20 V through a 470 Ω resistor, with no load connected. Find the current IR in the resistor.

Vin = 20 VVZ = 9.1 VR = 470 Ω
IR = mA
2.Easy
+−Vs​10 VR = 1.5 kΩD1​D2​I = ?

A 10 V DC source drives current through a 1.5 kΩ 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 = 1.5 kΩVD = 0.7 V
I = mA
3.Medium
RC​ = 2.7 kΩβ = 80RE​ = 1.2 kΩVCC​ = 20 VR1​ = 47 kΩR2​ = 10 kΩ

An NPN transistor with β = 80 has voltage-divider bias from VCC = 20 V: R₁ = 47 kΩ from VCC to the base and R₂ = 10 kΩ from the base to ground. The collector resistor is RC = 2.7 kΩ and the emitter resistor is RE = 1.2 kΩ. Take VBE = 0.7 V and use the Thévenin equivalent of the divider (do not neglect the base current). Find the collector–emitter voltage VCE.

VCC = 20 VR1 = 47 kΩR2 = 10 kΩRC = 2.7 kΩRE = 1.2 kΩβ = 80
VCE = V
4.Medium
+−20 V150 Ω6.2 V3300 ΩIZ​ = ?

A 6.2 V Zener regulator is fed from 20 V through 150 Ω and supplies a 3300 Ω load. Find the Zener current IZ.

Vin = 20 VVZ = 6.2 VR = 150 ΩRL = 3300 Ω
IZ = mA
5.Hard
RC​ = 100 Ωβ = 80VCC​ = 24 V3.3 VRB​ = ?

An NPN transistor with β = 80 switches a 100 Ω load resistor connected between VCC = 24 V and its collector. The emitter is grounded. The base is driven from a 3.3 V logic output through a base resistor RB. Take VBE = 0.7 V and VCE(sat) = 0.2 V. For reliable switching, design for a base current 3 times the minimum needed for saturation. Find RB in kΩ.

VCC = 24 VRC = 100 Ωβ = 80Vin = 3.3 VVBE = 0.7 VVCE(sat) = 0.2 Voverdrive = 3
RB = kΩ
6.Hard
+−≥ 18 VR = ?6.2 V≤ 20 mA

A 6.2 V Zener regulator must supply up to 20 mA to a load. The input can drop to 18 V, and the Zener needs at least 2 mA to regulate. Find the largest series resistance Rmax that keeps it regulating.

Vin,min = 18 VVZ = 6.2 VIL,max = 20 mAIZ,min = 2 mA
Rmax = Ω

Answer key

  1. 1. IR = 23.19 mA
  2. 2. I = 5.733 mA
  3. 3. VCE = 11.66 V
  4. 4. IZ = 90.12 mA
  5. 5. RB = 0.2913 kΩ
  6. 6. Rmax = 536.4 Ω

Full step-by-step solutions: practise this topic on examproblems.com.