IGNOU BPHET-143 June 2023 Previous Year Question Paper

Q1.Attempt any five parts : 2×5=10

(a) Draw the labelled I-V characteristics of an intrinsic semiconductor.

(b) Draw the circuit symbol s of an LED and a solar cell.

(c) Convert the octal number 3458 into its equivalent binary number.

(d) Draw the circuit symbol and write the truth table of 2-input XOR gate.

(e) Explain why class A amplifier is preferred in the audio circuits.

(f) In a voltage regulator, the no -load voltage is 15 V and full -load voltage is 14.5 V. Calculate the percentage voltage regulation.

(g) Calculate the gain of the circuit shown in the figure given below :

(h) What is a monostable multi-vibrator ?

Q2.Attempt any two parts :

(a) Explain the construction and working of a Zener diode and draw its labelled I -V characteristics. 4+1

(b) Draw the labelled drain characteristics of an n-channel JFET for zero gate -source (VGS = 0) voltage and explain them. 5

(c) Draw the load line and show the quiescent operating point on the output characteristics of a BJT in CE configuration. Explain their function in the operation of a transistor amplifier.

Q3.Attempt any two parts :

(a) Explain how a 2 -input OR gate is realised using p-n junction diodes. Write the truth table of OR gate and dra w its circuit symbol. 3+1+1

(b) Obtain the MSP expression for the following Boolean equation and draw its corresponding simplified logic circuit : 5

(c) Draw the truth table and symbol of a full adder for adding two 3 -bits binary numbers. Obtain the MSP for its sum and carry from the truth table using SOP method. 5 [ 4 ]

Q4.Attempt any two parts :

(a) For a CE amplifier biased using universal biasing of an n-p-n transistor, with VCE = 16 V, R 1 = 30 k , R 2 = 10 k , collector current = 10 mA, VCE = 7 V, VBE =

Q5.6 V and  = 50, calculate the values of collector resisto r R C and emitter resisto r RE. Also find the output voltage, at the collector of the transistor. 5

(b) Draw the circuit of Colpitts o scillator and explain its working . Write the e xpression for its frequency of oscillation. 4+1

(c) What is the function of a filter used in regulated power supply ? Explain the action of capacitance filter with appropriate waveforms.

Q6.Attempt any two parts :

(a) Draw the circuit of basic differentiator using an op-amp. Obtain the expression for its output voltage. 2+3

(b) Explain with appropriate waveforms, how a trace is obtained on the CRT screen. 5

(c) Draw the pin out diagram of IC 555. Explain the working of a monostable multi- vibrator using IC 555 with the help of a circuit diagram. 1+4 2023 -143 LED 3458 XOR 15 V