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​3 VR = 2.2 kΩD​I = ?

A 3 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 = 3 VR = 2.2 kΩVD = 0.7 V
I = mA
2.Easy
+−Vs​24 VR = 1 kΩD​I = ?

A 24 V DC source drives current through a 1 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 = 24 VR = 1 kΩVD = 0.7 V
I = mA
3.Medium
RC​ = 2.2 kΩβ = 80VCC​ = 15 VRB​ = 680 kΩ

An NPN transistor with β = 80 is biased by a base resistor RB = 680 kΩ from the supply VCC = 15 V. The collector resistor is RC = 2.2 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 = 15 VRB = 680 kΩRC = 2.2 kΩβ = 80VBE = 0.7 V
VCE = V
4.Medium
+−24 V100 Ω6.2 V1000 ΩIZ​ = ?

A 6.2 V Zener regulator is fed from 24 V through 100 Ω and supplies a 1000 Ω load. Find the Zener current IZ.

Vin = 24 VVZ = 6.2 VR = 100 ΩRL = 1000 Ω
IZ = mA
5.Hard
RC​ = 150 Ωβ = 80IC​ = ?VCC​ = 24 V5 VRB​ = 100 kΩ

An NPN transistor with β = 80 switches a 150 Ω load resistor connected between VCC = 24 V and its collector. The emitter is grounded. The base is driven from a 5 V logic output through a base resistor RB = 100 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 = 24 VRC = 150 Ωβ = 80Vin = 5 VVBE = 0.7 VVCE(sat) = 0.2 VRB = 100 kΩ
IC = mA
6.Hard
RC​ = 100 Ωβ = 200VCC​ = 5 V5 VRB​ = ?

An NPN transistor with β = 200 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. Take VBE = 0.7 V and VCE(sat) = 0.2 V. Find the largest base resistor RB, in kΩ, that still drives the transistor just into saturation.

VCC = 5 VRC = 100 Ωβ = 200Vin = 5 VVBE = 0.7 VVCE(sat) = 0.2 V
RB = kΩ

Answer key

  1. 1. I = 1.045 mA
  2. 2. I = 23.3 mA
  3. 3. VCE = 11.3 V
  4. 4. IZ = 171.8 mA
  5. 5. IC = 3.44 mA
  6. 6. RB = 17.92 kΩ

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