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​9 VR = 3.3 kΩD1​D2​I = ?

A 9 V DC source drives current through a 3.3 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 = 3.3 kΩVD = 0.7 V
I = mA
2.Easy
+−Vs​6 VR = 4.7 kΩD​I = ?

A 6 V DC source drives current through a 4.7 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 = 4.7 kΩVD = 0.7 V
I = mA
3.Medium
RC​ = 1 kΩβ = 120VCC​ = 15 VRB​ = 560 kΩ

An NPN transistor with β = 120 is biased by a base resistor RB = 560 kΩ from the supply VCC = 15 V. The collector resistor is RC = 1 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 = 560 kΩRC = 1 kΩβ = 120VBE = 0.7 V
VCE = V
4.Medium
+−20 V680 Ω5.1 V680 ΩIZ​ = ?

A 5.1 V Zener regulator is fed from 20 V through 680 Ω and supplies a 680 Ω load. Find the Zener current IZ.

Vin = 20 VVZ = 5.1 VR = 680 ΩRL = 680 Ω
IZ = mA
5.Hard
V (V)I (mA)0.65640Q = ?

A diode is modelled as 0.65 V in series with 20 Ω (it conducts above 0.65 V). It is in series with a 150 Ω resistor across a 6 V supply. Find the operating current ID where the diode line meets the load line.

Vs = 6 VR = 150 ΩV0 = 0.65 Vrd = 20 Ω
ID = mA
6.Hard
RC​ = 330 Ωβ = 200VCC​ = 5 V5 VRB​ = ?

An NPN transistor with β = 200 switches a 330 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 = 330 Ωβ = 200Vin = 5 VVBE = 0.7 VVCE(sat) = 0.2 V
RB = kΩ

Answer key

  1. 1. I = 2.303 mA
  2. 2. I = 1.128 mA
  3. 3. VCE = 11.94 V
  4. 4. IZ = 14.41 mA
  5. 5. ID = 31.47 mA
  6. 6. RB = 59.13 kΩ

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