ELECTRONICS DEVICES AND CIRCUITS  QUESTION PAPERS FOR S3 CS

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY

PART A

1.Design a clipper circuit that eliminates the positive portion of this AC waveform, leaving only the negative half-cycles to appear on the output:
2.Design a circuit whose output will be in dc and should be multiple of its peak ac input voltage.

3.What is an SMPS? Where is it used?

4.“A depletion mode MOSFET can also be operated in enhancement mode but an enhancement mode MOSFET cannot be operated in depletion mode”. Justify?

PART B

5 (A).While doing an experiment in the circuit lab, Mr. Paul has given a square wave instead of sine wave as the input to the circuit.

As he started varying the frequency, he observed that when the frequency is high, the CRO shows a triangular wave as the output and when the frequency is decreased, slowly the output is changed from triangular to square wave shape.

Identify the circuit and write the reason for that result (4.5)

(B) Draw a circuit using a transistor for generating sweep waveform. (4.5)

6.(A)Explain the basic principle of high current short circuit protected regulator. (4. 5)

(B)Explain with neat sketch, the current limiting features of IC 723 voltage regulator.(4.5)

7.(A)Compare the merits & demerits of a Bipolar Junction Transistor (BJT) with Field effect Transistor in detail (3)

(B) A 125 volt square with period of 25ms is to be negatively clamped at 50 v.

Draw the circuit diagram required to accomplish it. Sketch the input and output waveforms. (6)

Part C