https:\/\/learnexams.com\/search\/study?query=<\/a>
What are 5 parts of a power supply? Input, rectifier, filter, regulator, protection
Which two parts of a power supply are optional? Regulator and protection
What is the purpose of a power supply? To convert AC power into smooth DC power
What does the input of a power supply do? Step up or down the AC input voltage
What does the rectifier do in a power supply? Changes AC into pulsating DC
What does the filter do in a power supply? Changes pulsating DC into smooth DC
How type of components do filters use? Reactive components
What does a regulator do in a power supply? maintains the output voltage at a constant level despite changes in load current
What does the protection circuit do in power supply? Prevents damage to power supply if load becomes faulty, limits or disables output
The half wave rectifier is the same as what circuit? Series limiter
Which rectifier is the least efficient using only half the input? Half-wave
Which two rectifiers require two input signals 180 degrees out of phase? Full-wave and bridge
Which rectifier uses a center tapped transformer? Full wave
How is frequency determined for half wave rectifier? Output frequency is same as input frequency
How is frequency determined for full wave rectifier? Output is twice the input frequency
How is frequency determined for bridge rectifier? Output is twice the input frequency
What is the purpose of series voltage regulators? To adjust voltage drop to maintain V out at constant level
In a series voltage regulator, V out INCREASES when what happens? Load current decreases OR DC input increases
In series voltage regulator, V out DECREASES when what happens? Load current increases OR DC input decreases
If load current decreases or DC input increases, what needs to be done to maintain constant level of V out (series volt regulator)? Increase R1 resistance to increase voltage drop on R1
If load current increases or DC input decreases, what needs to be done to maintain constant level of V out (series voltage regulator)? Increase R1 resistance to decreases voltage drop on R1
What is the purpose of parallel voltage regulator? Adjust current flow to maintain V out at constant level
In parallel voltage regulator, V out increases when what happens? DC input increases or load current decreases
In parallel voltage regulator, V out decreases when what happens? When DC input decreases or load current increases
What makes a zener diode different from junction diode? Zener diode is designed operate in breakdown
When does zener diode conduct reverse current? When reverse bias voltage is HIGHER than Vz (diode acts like resistor)
When diode is forward biased, what is the output voltage in shunt regulator? 0.7V
When reverse biased lower than Vz, what happens to zener diode? Acts like an open
If reverse biased lower than Vz, what is output voltage of shunt regulator? Output is applied voltage
When reverse biased higher than Vz, what is the output voltage of shunt regulator? Vz
Which component changes resistances to maintain constant V out (zener diode regulator)? Q1
Which component sets output voltage (zener diode regulator)? D1 (holds Q1 at Vz)
The voltage on emitter is established by what in zener diode regulator? Action of Q1
If voltage increases what must happen to keep output voltage constant (zener diode regulator)? Q1 collector-emitter resistance must increase
If voltage decreases what must happen to keep output voltage constant (zener diode regulator)? Q1 collector-emitter resistance must decrease
In a voltage regulator, which component maintains a constant V out? Q1
In a voltage regulator, which components set voltage? D1 and Q2
What does R2 do in voltage regulator? Varies conduction of Q2 (changes Vce)
If input voltage increases in voltage regulator, Q2 must do what to maintain constant output? Increase resistance to drop more voltage (voltage of Q2 increase)
If input voltage decreases in voltage regulator, Q2 must do what to maintain constant output? Decrease resistance to drop less voltage (voltage of Q2 decrease)
If load current increases in voltage regulator, how is base to emitter biasing affected? FB increases
If load current decreases in voltage regulator, how is base to emitter biasing affected? FB decreases
If load current increases in voltage regulator what needs to be done to maintain constant output? Decrease resistance to drop less voltage
If load current increases in voltage regulator, what needs to be done to maintain constant output? Decrease resistance to drop less volts
What two conditions cause Vout to INCREASE in voltage regulator? Input voltage increases or load current decreases
What two conditions cause Vout to DECREASE in voltage regulator? Input voltage decreases or load current increases
What are the most common faults in voltage regulators? Semiconductor components (transistors\/diodes)
In a zener diode regulator, which faults cause output voltage to approach applied voltage? D1 open, Short between Collector-Emitter
In zener diode regulator, which faults cause output voltage to be 0V? D1 short\/R1 Open, open between Base-Emitter
Which fault in zener diode regulation can damage diode? R1 short
How do you calculate base voltage of Q1 in voltage regulator? Vz + Vce = Vb
Which fault in zener diode \/voltage regulator causes Q1 base voltage to increase and approach saturation? D1 Open
Which fault in zener diode \/ voltage regulator causes Q1 base voltage to decreases and approach cutoff? D1 short (no output volts)
Which faults cause output voltage to approach applied volts in voltage regulator? D1 open, R1 short, Q1 short Collector-Emitter
Which faults cause output voltage to be 0V in voltage regulator? R1 open, open Q1 base-emitter
Which faults cause output voltage to decrease in voltage regulator? D1 short, Q2 short
What are two benefits of IC regulators? Safe\/durable (thermal overload protection\/current limiting protection)
A constant 12 VDC output is maintained when input is between what values? (IC regulator) 14.5-30V
What is max current output in 7812 IC regulator? 1.5A (RL never below 8 ohms)
What is the purpose of unijunction transistors? Switch voltage, turn on when input exceeds specific level
What type material are the bases in unijunction transistor? N-type
When is unijunction transistor on? When current flows from emitter to base 1
How is turn on voltage determined unijunction transistor? Eta times Vcc
What is the purpose of silicon control rectifier? Switch current on and off, turns on when current is applied to gate
The gate is attached to which part of diode in SCR? Cathode
What type of material is gate in SCR? Very thin p-type material
When will current flow in SCR? When diode is forward biased AND positive current flow is attached to gate
What happens when gate current is removed in SCR? Nothing, diode is latched on
How is SCR turned off? Current flow must be interrupted with switch or by shorting anode to cathode
What is the range of trigger currents in SCR? 2mA to 20mA
What is a purpose of relays? Used for applying power to circuits or controlling signal flow
What are two benefits of relays? Can handle higher levels of current, make large power transfers possible
How are relays shown on schematics? De-Energized
Saying contacts are normally closed or normally open refers to them in which state? De-energized
What are 4 parts of relay? magnetic coil, contacts, armature, spring
What replaces armature in multipole relays? Clapper and push rod
What is one type of time delay relay? Bimetallic thermal relay
What is difference between solenoid and relay? Solenoid has movable core (plunger), core tries to center itself in mag field
What are typical faults in relays? Faulted magnetic coil or faulted contacts
What fault is caused by current flowing in one direction in contacts? Coned or cratered contacts
What is used to fix burned contacts? Burnishing tool
What is TS procedure for relays? Check inputs, check outputs
What is TS procedure for electrical circuits? Analyze, check setup, calculate\/measure, check results
What are most common faults in electrical circuits? Open\/short
If a diode is shorted in power supply what happens? LED wont illuminate, AC isnt converted to DC
If diode is open in power supply what happens? LED wont illuminate, pulsating DC missing cycle
What are three circuits in an op amp? Differential amp, common collector amp, push pull amp
What is the purpose of op amps? Use two inputs to determine an output (versatile, replace transistors)
What does + indicate on op amp? Non-inverting
What does – indicate on op amp? Inverting
Using both inputs produces what type of amp? Diffential
Connecting several inputs to inverting (-) input produces which type of amp? Summing amp
How are op amps packaged? IC chip
Where does most of amplification happen in op amp? Pushpull amp
External circuits stabilize op amp operation using what type of feedback? Degenerative
What is the point of degenerative feedback in op amp? Reduces gain
What is typical gain of differential amp? 1
How do you determine output of summing amp? Output = -(input1 + input2)<\/p>\n","protected":false},"excerpt":{"rendered":"ATT Test 8 (Latest 2024\/ 2025 Update) Questions and Verified Answers| 100% Correct| Grade A ATT Test 8 (Latest 2024\/ 2025 Update)Questions and Verified Answers| 100%Correct| Grade AQ: Which rectifier is the least efficient using only half the input?Answer:Half-waveQ: Which two rectifiers require two input signals 180 degrees out of phase?Answer:Full-wave and bridgeQ: Which rectifier […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-131721","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/131721","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=131721"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/131721\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=131721"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=131721"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=131721"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}