Chapter 21 Mendoza
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Transcript of Chapter 21 Mendoza
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Chapter 21Power Supplies
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1. The output rectifer is:
A. 60-Hz ac. B. Smooth dc.
C. Pulsating dc.
. 120-Hz ac.
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2 . Which o the ollowing might not be needed in power supply?
A. !he trans"ormer.
B. !he #lter.
C. !he recti#er.
. All o" the a$o%e are generall& needed.
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3. O the ollowing appliances, which would neebiggest transormer?
A. A cloc' radio. B. A !( $roadcast transmitter.
C. A shortwa%e radio recei%er.
. A home !( set.
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. !n ad"antage o ull#wa"e bridge rectifca
A. )t uses the whole trans"ormer secondathe entire ac input c&cle.
B. )t costs less than other recti#er t&pes.
C. )t cuts o* hal" o" the ac wa%e c&cle.
. )t ne%er needs a regulator.
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$. %n. a supply designed to pro"ide high power"oltage, the best rectifer design would proba
A. Hal"-wa%e.
B. +ull-wa%e, center-tap.
C. Bridge.
. (oltage multiplier.
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&. The part o a power supply immediately precethe regulator is:
A. !he trans"ormer. B. !he recti#er.
C. !he #lter.
. !he ac input.
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'. % a hal#wa"e rectifer is used with 11'#( rms )house mains*, the a"erage dc output "oltage is
A. 2. (. B. 10 (.
C. 11 (.
. /2 (.
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Solution
11rms 2 3 16.46(p
A%erage %alue output
(a%g 3 3 3 52.668V or 52.67V
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+. % a ull#wa"e bridge circuit is used with atransormer whose secondary pro"ides $ the -%( across the diodes is about:
A. 0 (. B. 0 (.
C. 100 (.
. 140 (.
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. The principal disad"antage o a "oltage multi
A. 7cessi%e current. B. 7cessi%e %oltage.
C. )nsu8cient recti#cation.
. Poor regulation.
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1. ! transormer secondary pro"ides 1 ( rms t"oltage#doubler circuit. The dc output "oltage is
A. 14 (. B. 20 (.
C. 2 (.
. /6 (.
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11. The ripple re/uency rom a ull#wa"e rect
A. !wice that "rom a hal"-wa%e circuit. B. !he same as that "rom a hal"-wa%e circ
C. Hal" that "rom a hal"-wa%e circuit.
. 9ne-"ourth that "rom a hal"-wa%e circu
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10. Which o the ollowing would mae the besor a power supply?
A. A capacitor in series. B. A cho'e in series.
C. A capacitor in series and a cho'e in parallel.
. A capacitor in parallel and a cho'e in series.
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13. % you needed e2ceptionally good ripple fltera power supply, the best approach would be to:
A. Connect se%eral capacitors in parallel. B. :se a cho'e-input #lter.
C. Connect se%eral cho'es in series.
. :se two capacitor;cho'e sections one
the other.
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1. (oltage regulation can be accomplished by adiode connected in:
A. Parallel with the #lter output, "orward-$ B. Parallel with the #lter output, re%erse-$
C. Series with the #lter output, "orward-$
. Series with the #lter output, re%erse-$
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1$. ! current surge taes place when a power sufrst turned on because:
A. !he trans"ormer core is suddenl&magnetized.
B. !he diodes suddenl& start to conduct.
C. !he #lter capacitor
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1&. Transient suppression minimi4es the cha
A. iode "ailure. B. !rans"ormer "ailure.
C. +ilter capacitor "ailure.
. Poor %oltage regulation.
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1'. % a use blows, and it is replaced with one halower current rating, there5s a good chance that:
A. !he power suppl& will $e se%erel& dam B. !he diodes will not recti"&.
C. !he "use will $low out right awa&.
. !ransient suppressors won>t wor'.
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1+. ! use with nothing but a straiwire inside is probably:
A. A slow-$low t&pe. B. A ?uic'-$rea' t&pe.
C. 9" a low current rating.
. 9" a high current rating.
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1. 6leeder resistors are:
A. Connected in parallel with #lter capacitors.
B. 9" low ohmic %alue.
C. *ecti%e "or transient suppression.
. *ecti%e "or surge suppression.
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0. To ser"ice a power supply withwhich you are not completely ami
you should: A. )nstall $leeder resistors.
B. :se proper "using.
C. @ea%e it alone and ha%e a pro"essionalon it.
. :se a %oltage regulator.