Indian Institute of Technology Kharagpur
BASIC ELECTRONICS(EC21201)
Chapter 2: Diode Circuits
Problems set 2
Q1. Consider the circuit shown. The input voltage is 𝑣𝑠 (𝑡) = 15sin𝜔𝑡 V and the diode cut-in voltage is 𝑉𝛾 =
0.7 V. The voltage 𝑉𝐵 varies between 4 V ≤ 𝑉𝐵 ≤ 8 V. The peak current is to be limited to 𝑖𝐷 (peak) = 18 mA.
Determine the range of peak current.
(a) 11 mA ≤ 𝑖𝐷 (peak) ≤ 18 mA
(b) 21 mA ≤ 𝑖𝐷 (peak) ≤ 18mA
(c) 21 mA ≤ 𝑖𝐷 (peak) ≤ 28 mA
(d) 11 mA ≤ 𝑖𝐷 (peak) ≤ 28 mA
Q2. Consider the circuit shown. The input voltage is 𝑣𝑠 (𝑡) = 15sin𝜔𝑡 V and the diode cut-in voltage is 𝑉𝛾 =
0.7 V. The voltage 𝑉𝐵 varies between 4 V ≤ 𝑉𝐵 ≤ 8 V.If the output voltage 𝑣𝑂 (𝑡) is taken across 𝑅,then
determine the range of the percentage duty cycle of this output voltage.
Note:The value of 𝑅 won’t affect the Duty cycle so it’s not necessary.
(a) 30.3% ≤ %DutyCycle ≤ 49.9%
(b) 30.3% ≤ %DutyCycle ≤ 39.9%
(c) 40.3% ≤ %DutyCycle ≤ 49.9%
(d) 40.3% ≤ %DutyCycle ≤ 49.9%
Q3. In the circuit shown below, a Zener diode is used to maintain a constant voltage of 8 V across a load
resistance 𝑅𝐿 = 5 kΩ after breakdown. The Zener diode has a power rating of 0.32 W. The series resistance
𝑅𝑖 = 100 Ω. Determine the range of the input power supply voltage 𝑉𝑃𝑆 that ensures the Zener diode maintains
the constant 8 V across the load resistance 𝑅𝐿 , without exceeding its power rating.
(a) 8.16 V ≤ 𝑉𝑃𝑆 ≤ 12.16 V
(b) 16.16 V ≤ 𝑉𝑃𝑆 ≤ 22.16 V
(c) 8.16 V ≤ 𝑉𝑃𝑆 ≤ 22.16 V
(d) 22.16 V ≤ 𝑉𝑃𝑆 ≤ 27.16 V
Q4. A voltage regulator shown below is to have a nominal output voltage of 10 V. The specified Zener diode has
a rating of 1 W, has a 10 V drop at 𝐼𝑍 = 25 mA, and has a Zener resistance of 𝑟𝑧 = 5 Ω. The input power supply
has a nominal value of 𝑉𝑃𝑆 = 20 V and can vary by ±25%. The output load current is to vary between 𝐼𝐿 = 0
and 20 mA. If the minimum Zener current is to be 𝐼𝑍 = 5 mA, then determine the maximum variation in output
voltage due to changes in 𝑉𝑃𝑆 , and calculate the source regulation.
(a) 5V and 50%
(b) 0.75V and 7.5%
(c) 1V and 10%
(d) 0.1875V and 1.875%
Q5. A limiter circuit is shown below
Assuming the forward voltage drop of the diodes to be 𝑉𝛾 = 0.7V and the reverse break down voltage of the
Zener diode 𝑉𝑧 = 10V, the input-output transfer characteristics of the circuit is depicted
Q6 A voltage signal 𝑉𝑖𝑛 = 10𝑠𝑖𝑛𝑤𝑡 is applied to the circuit with ideal diodes(i.e 𝑉𝛾 = 0V), as shown in the figure
below . What are the maximum and minimum values of the output 𝑉𝑜𝑢𝑡 waveform of the circuit are respectively?
(a) 𝑉𝑚𝑎𝑥 = +10V and 𝑉𝑚𝑖𝑛 = −10V
(b) 𝑉𝑚𝑎𝑥 = +4V and 𝑉𝑚𝑖𝑛 = −4V
(c) 𝑉𝑚𝑎𝑥 = +7V and 𝑉𝑚𝑖𝑛 = −4V
(d) 𝑉𝑚𝑎𝑥 = +4V and 𝑉𝑚𝑖𝑛 = −7V