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​5 VR = 2.2 kΩD1​D2​I = ?

A 5 V DC source drives current through a 2.2 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 = 5 VR = 2.2 kΩVD = 0.7 V
I = mA
2.Easy
+−Vs​6 VR = 2.2 kΩD​I = ?

A 6 V DC source drives current through a 2.2 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 = 6 VR = 2.2 kΩVD = 0.7 V
I = mA
3.Medium
RC​ = 1.5 kΩβ = 100RE​ = 2.2 kΩVCC​ = 18 VR1​ = 22 kΩR2​ = 22 kΩ

An NPN transistor with β = 100 has voltage-divider bias from VCC = 18 V: R₁ = 22 kΩ from VCC to the base and R₂ = 22 kΩ from the base to ground. The collector resistor is RC = 1.5 kΩ and the emitter resistor is RE = 2.2 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 = 18 VR1 = 22 kΩR2 = 22 kΩRC = 1.5 kΩRE = 2.2 kΩβ = 100
VCE = V
4.Medium
RC​ = 1.5 kΩβ = 120RE​ = 1.2 kΩVCC​ = 18 VR1​ = 33 kΩR2​ = 15 kΩ

An NPN transistor with β = 120 has voltage-divider bias from VCC = 18 V: R₁ = 33 kΩ from VCC to the base and R₂ = 15 kΩ from the base to ground. The collector resistor is RC = 1.5 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 = 18 VR1 = 33 kΩR2 = 15 kΩRC = 1.5 kΩRE = 1.2 kΩβ = 120
VCE = V
5.Hard
+−≥ 15 VR = ?5.6 V≤ 40 mA

A 5.6 V Zener regulator must supply up to 40 mA to a load. The input can drop to 15 V, and the Zener needs at least 5 mA to regulate. Find the largest series resistance Rmax that keeps it regulating.

Vin,min = 15 VVZ = 5.6 VIL,max = 40 mAIZ,min = 5 mA
Rmax = Ω
6.Hard
RC​ = 100 Ωβ = 100IC​ = ?VCC​ = 5 V5 VRB​ = 220 kΩ

An NPN transistor with β = 100 switches a 100 Ω load resistor connected between VCC = 5 V and its collector. The emitter is grounded. The base is driven from a 5 V logic output through a base resistor RB = 220 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 = 5 VRC = 100 Ωβ = 100Vin = 5 VVBE = 0.7 VVCE(sat) = 0.2 VRB = 220 kΩ
IC = mA

Answer key

  1. 1. I = 1.636 mA
  2. 2. I = 2.409 mA
  3. 3. VCE = 4.753 V
  4. 4. VCE = 7.701 V
  5. 5. Rmax = 208.9 Ω
  6. 6. IC = 1.955 mA

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