Cochin University of Science and Techology (CUST) 2007-2nd Year B.E Electrical and Electronics Engineering btech electronic devices and circuits - Question Paper

BTECH DEGREE 1st TERM exam SEPTEMBER 2007
ELECTRONIC DEVICES& CIRCUITS.

Time: 2Hrs Max marks:50

PART A

1. discuss the DC power supply with block diagram.

2. discuss the principle & operation of Photodiode, PIN diode& Phototransistor.

3. discuss the pulse characteristics.

4. discuss the positive& negative clippers with neat ckt diagram.

PART B

5. a) discuss voltage multipliers.
b) An ac supply of 230 v is applied to a half wave rectifier ckt through a T/F of turns
ratio 10:1 .Determine
1. Im,Idc&Irms
2. dc power o/p.
3. ac power o/p.
4. efficiency of rectification.
5. dc o/p voltage.
6. Peak inverse voltage
presume that the crystal diode has a forward resistance of 20 ohm& the load
resistance is one Kilo ohm

6. a) discuss the working of T/F as a switch.

b) A bridge rectifier is supplying a load of 200mA at 30V. It uses a pi-section filter
with a choke of 0.5 H & two capacitors every of 80 microF. presume the supply
frequency of 50 Hz. obtain (i)the i/p rms voltage of the secondary of the T/F.(ii) the
percentage ripple in o/p.

7. a) discuss the Breeder resistor& voltage regulation.

b) discuss astable, monostable& bistable multivibrators using BJT’s.

8. a) discuss zener& avalanche diode.

b) A full wave rectifier has a peak o/p voltage of 25 V at 50Hz.& feeds a resistive load of 1Kohm. The filter used is shunt capacitor 1 with C=20 microfarad. Determine (i) dc load current(ii) dc o/p voltage(iii) ripple voltage(iv) ripple factor.
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Earning:   Approval pending.