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 = 470 ΩD​I = ?

A 10 V DC source drives current through a 470 Ω resistor in series with a forward-biased silicon diode. Use the constant-drop model with 0.7 V per conducting diode. Find the current I in mA.

Vs = 10 VR = 470 ΩVD = 0.7 V
I = mA
2.Easy
+−Vs​3 VR = 3.3 kΩD​I = ?

A 3 V DC source drives current through a 3.3 kΩ resistor in series with a forward-biased silicon diode. Use the constant-drop model with 0.7 V per conducting diode. Find the current I in mA.

Vs = 3 VR = 3.3 kΩVD = 0.7 V
I = mA
3.Medium
RC​ = 4.7 kΩβ = 50VCC​ = 9 VRB​ = 560 kΩ

An NPN transistor with β = 50 is biased by a base resistor RB = 560 kΩ from the supply VCC = 9 V. The collector resistor is RC = 4.7 kΩ and the emitter is grounded. Take VBE = 0.7 V and assume the transistor is in the active region. Find the collector–emitter voltage VCE.

VCC = 9 VRB = 560 kΩRC = 4.7 kΩβ = 50VBE = 0.7 V
VCE = V
4.Medium
RC​ = 1 kΩβ = 150IC​ = ?RE​ = 1.2 kΩVCC​ = 12 VR1​ = 47 kΩR2​ = 15 kΩ

An NPN transistor with β = 150 has voltage-divider bias from VCC = 12 V: R₁ = 47 kΩ from VCC to the base and R₂ = 15 kΩ from the base to ground. The collector resistor is RC = 1 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 current IC in mA.

VCC = 12 VR1 = 47 kΩR2 = 15 kΩRC = 1 kΩRE = 1.2 kΩβ = 150
IC = mA
5.Hard
V (V)I (mA)0.633Q = ?

A diode is modelled as 0.6 V in series with 25 Ω (it conducts above 0.6 V). It is in series with a 1000 Ω resistor across a 3 V supply. Find the operating current ID where the diode line meets the load line.

Vs = 3 VR = 1000 ΩV0 = 0.6 Vrd = 25 Ω
ID = mA
6.Hard
+−≥ 12 VR = ?6.2 V≤ 40 mA

A 6.2 V Zener regulator must supply up to 40 mA to a load. The input can drop to 12 V, and the Zener needs at least 5 mA to regulate. Find the largest series resistance Rmax that keeps it regulating.

Vin,min = 12 VVZ = 6.2 VIL,max = 40 mAIZ,min = 5 mA
Rmax = Ω

Answer key

  1. 1. I = 19.79 mA
  2. 2. I = 0.697 mA
  3. 3. VCE = 5.517 V
  4. 4. IC = 1.716 mA
  5. 5. ID = 2.341 mA
  6. 6. Rmax = 128.9 Ω

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