STUDY NOTES       QUESTIONS WITHOUT ANSWERS 

1. The block marked 'Filter' in the diagram is to:
   1. filter RF radiation from the output of the power supply
   2. smooth the rectified waveform from the rectifier
   3. act as a 50 Hz tuned circuit
   4. restore voltage variations
   ========= Answer is b =========
   
2. The block marked 'Regulator' in the diagram is to:
   1. regulate the incoming mains voltage to a constant value
   2. ensure that the output voltage never exceeds a dangerous value
   3. keep the incoming frequency constant at 50 Hz
   4. keep the output voltage at a constant value
   ========= Answer is d =========
   
3. The block marked 'Transformer' in the diagram is to:
   1. transform the incoming mains AC voltage to a DC voltage
   2. ensure that any RF radiation cannot get into the power supply
   3. transform the mains AC voltage to a more convenient AC voltage
   4. transform the mains AC waveform into a higher frequency waveform
   ========= Answer is c =========
   
4. The block marked 'Rectifier' in the diagram is to:
   1. turn the AC voltage from the transformer into a fluctuating DC voltage
   2. rectify any waveform errors introduced by the transformer
   3. turn the sinewave output of the rectifier into a square wave
   4. remove any AC components from the output of the transformer
   ========= Answer is a =========
   
5. The block marked 'Regulator' in the diagram could consist of:
   1. four silicon power diodes in a regulator configuration
   2. two silicon power diodes and a centre-tapped transformer
   3. a three-terminal regulator chip
   4. a single silicon power diode connected as a half-wave rectifier
   ========= Answer is c =========
   
6. The power supply in the diagram is to replace a car battery to power a solid-state transceiver to full amateur ratings. A typical expected maximum current load will be:
   1. 1 - 5 amp
   2. 6 - 8 amp
   3. 20 - 25 amp
   4. 30 - 60 amp
   ========= Answer is d =========
   
7. A power supply is to power a solid-state transceiver. A suitable over-voltage protection device is a:
   1. crowbar across the regulator output
   2. 100 uF capacitor across the transformer output
   3. fuse in parallel with the regulator output
   4. zener diode in series with the regulator
   ========= Answer is a =========
   
8. In a regulated power supply, the 'crowbar' is a:
   1. means to lever up the output voltage
   2. circuit for testing mains fuses
   3. last-ditch protection against failure of the regulator in the supply
   4. convenient means to move such a heavy supply unit
   ========= Answer is c =========
   
9. In a regulated power supply, 'current limiting' is sometimes used to:
   1. prevent transformer core saturation
   2. protect the mains fuse
   3. minimise short-circuit current passing through the regulator
   4. eliminate earth-leakage effects
   ========= Answer is c =========
   
10. The purpose of a series pass transistor in a regulated power supply is to:
    1. suppress voltage spikes across the transformer secondary winding
    2. work as a surge multiplier to speed up regulation
    3. amplify output voltage errors to assist regulation
    4. maintain the output voltage at a constant value
    ========= Answer is d =========