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150 lines
3.6 KiB
Plaintext
150 lines
3.6 KiB
Plaintext
% FILENAME = N22.TXT
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% Regulated Power Supplies
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% Release version 3, October 2001
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% Q 4, 10 corrected 6 Mar 2012
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%Question: 1
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#22.1 The block marked 'Filter' in the diagram is to:
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<img src = "regps.gif" align = center width = 511 height = 129>
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<totallines = 13 >
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filter RF radiation from the output of the power supply
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smooth the rectified waveform from the rectifier
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act as a 50 Hz tuned circuit
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restore voltage variations
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% ans 2
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%Question: 2
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#22.2 The block marked 'Regulator' in the diagram is to:
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<img src = "regps.gif" align = center width = 511 height = 129>
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<totallines = 13 >
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regulate the incoming mains voltage to a constant value
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ensure that the output voltage never exceeds a dangerous value
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keep the incoming frequency constant at 50 Hz
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keep the output voltage at a constant value
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% ans 4
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%Question: 3
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#22.3 The block marked 'Transformer' in the diagram is to:
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<img src = "regps.gif" align = center width = 511 height = 129>
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<totallines = 13 >
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transform the incoming mains AC voltage to a DC voltage
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ensure that any RF radiation cannot get into the power supply
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transform the mains AC voltage to a more convenient AC voltage
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transform the mains AC waveform into a higher frequency waveform
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% ans 3
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%Question: 4
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#22.4 The block marked 'Rectifier' in the diagram is to:
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<img src = "regps.gif" align = center width = 511 height = 129>
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<totallines = 13 >
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turn the AC voltage from the transformer into a fluctuating DC voltage
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rectify any waveform errors introduced by the transformer
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turn the sinewave output of the rectifier into a square wave
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smooth the DC waveform
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% ans 1
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%Question: 5
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#22.5 The block marked 'Regulator' in the diagram could consist of:
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<img src = "regps.gif" align = center width = 511 height = 129>
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<totallines = 13 >
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four silicon power diodes in a regulator configuration
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two silicon power diodes and a centre-tapped transformer
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a three-terminal regulator chip
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a single silicon power diode connected as a half-wave rectifier
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% ans 3
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%Question: 6
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#22.6 In the block marked regulator in the diagram below, a reversed diode may be present across the regulator. Its job is to
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<img src = "regps.gif" align = center width = 511 height = 129>
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<totallines = 15 >
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Block negative voltages from appearing at the output
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Blow a fuse if high voltages occur at the output
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Blow a fuse if negative currents occur at the output
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Bypass the regulator for higher voltage at its output compared to its input
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% ans 4
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%Question: 7
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#22.7 A power supply is to power a solid-state transceiver. A suitable
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over-voltage protection device is a:
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crowbar across the regulator output
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100 uF capacitor across the transformer output
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fuse in parallel with the regulator output
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zener diode in series with the regulator
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% ans 1
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%Question: 8
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#22.8 In a regulated power supply, the 'crowbar' is a:
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means to lever up the output voltage
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circuit for testing mains fuses
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last-ditch protection against failure of the regulator in the supply
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convenient means to move such a heavy supply unit
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% ans 3
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%Question: 9
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#22.9 In a regulated power supply, 'current limiting' is sometimes used to:
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prevent transformer core saturation
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protect the mains fuse
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minimise short-circuit current passing through the regulator
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eliminate earth-leakage effects
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% ans 3
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%Question: 10
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#22.10 The purpose of a series pass transistor in a regulated power supply is
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to:
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suppress voltage spikes across the transformer secondary winding
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work as a surge multiplier to speed up regulation
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amplify output voltage errors to assist regulation
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Allow for a higher current to be supplied than the regulator would otherwise allow
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% ans 4
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