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
+−15 V150 Ω3.3 VIR​ = ?

A 3.3 V Zener diode is fed from 15 V through a 150 Ω resistor, with no load connected. Find the current IR in the resistor.

Vin = 15 VVZ = 3.3 VR = 150 Ω
IR = mA
2.Easy
+−Vs​9 VR = 4.7 kΩD1​D2​I = ?

A 9 V DC source drives current through a 4.7 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 = 9 VR = 4.7 kΩVD = 0.7 V
I = mA
3.Medium
RC​ = 2.2 kΩβ = 100IC​ = ?RE​ = 470 ΩVCC​ = 15 VR1​ = 82 kΩR2​ = 10 kΩ

An NPN transistor with β = 100 has voltage-divider bias from VCC = 15 V: R₁ = 82 kΩ from VCC to the base and R₂ = 10 kΩ from the base to ground. The collector resistor is RC = 2.2 kΩ and the emitter resistor is RE = 470 Ω. Take VBE = 0.7 V and use the Thévenin equivalent of the divider (do not neglect the base current). Find the collector current IC in mA.

VCC = 15 VR1 = 82 kΩR2 = 10 kΩRC = 2.2 kΩRE = 470 Ωβ = 100
IC = mA
4.Medium
+−12 V270 Ω3.3 V1500 ΩIZ​ = ?

A 3.3 V Zener regulator is fed from 12 V through 270 Ω and supplies a 1500 Ω load. Find the Zener current IZ.

Vin = 12 VVZ = 3.3 VR = 270 ΩRL = 1500 Ω
IZ = mA
5.Hard
+−≤ 24 V680 Ω9.1 V

A 9.1 V Zener regulator has a 680 Ω series resistor. The input can rise to 24 V, and the load may be disconnected. Find the largest power PZ,max the Zener must dissipate.

Vin,max = 24 VVZ = 9.1 VR = 680 Ω
PZ,max = mW
6.Hard
RC​ = 470 Ωβ = 150VCC​ = 5 V3.3 VRB​ = ?

An NPN transistor with β = 150 switches a 470 Ω load resistor connected between VCC = 5 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 10 times the minimum needed for saturation. Find RB in kΩ.

VCC = 5 VRC = 470 Ωβ = 150Vin = 3.3 VVBE = 0.7 VVCE(sat) = 0.2 Voverdrive = 10
RB = kΩ

Answer key

  1. 1. IR = 78 mA
  2. 2. I = 1.617 mA
  3. 3. IC = 1.65 mA
  4. 4. IZ = 30.02 mA
  5. 5. PZ,max = 199.4 mW
  6. 6. RB = 3.819 kΩ

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