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ATT TEST 8 ACTUAL TEST 2025 | ALL QUESTIONS
AND CORRECT ANSWERS | GRADED A+ | VERIFIED
ANSWERS | LATEST TEST (JUST RELEASED)
What is difference between solenoid and relay? ---------CORRECT ANSWER-----------------Solenoid has movable core (plunger), core tries to center itself in mag field What are typical faults in relays? ---------CORRECT ANSWER----------------- Faulted magnetic coil or faulted contacts What fault is caused by current flowing in one direction in contacts? --------- CORRECT ANSWER-----------------Coned or cratered contacts What is used to fix burned contacts? ---------CORRECT ANSWER------------- ----Burnishing tool What is TS procedure for relays? ---------CORRECT ANSWER----------------- Check inputs, check outputs What is TS procedure for electrical circuits? ---------CORRECT ANSWER--- --------------Analyze, check setup, calculate/measure, check results What are most common faults in electrical circuits? ---------CORRECT ANSWER-----------------Open/short
If a diode is shorted in power supply what happens? ---------CORRECT ANSWER-----------------LED wont illuminate, AC isnt converted to DC If diode is open in power supply what happens? ---------CORRECT ANSWER-----------------LED wont illuminate, pulsating DC missing cycle What are three circuits in an op amp? ---------CORRECT ANSWER----------- ------Differential amp, common collector amp, push pull amp What is the purpose of op amps? ---------CORRECT ANSWER----------------- Use two inputs to determine an output (versatile, replace transistors) What does + indicate on op amp? ---------CORRECT ANSWER----------------
- Non-inverting What does - indicate on op amp? ---------CORRECT ANSWER----------------- Inverting Using both inputs produces what type of amp? ---------CORRECT ANSWER-----------------Diffential Connecting several inputs to inverting (-) input produces which type of amp? ---------CORRECT ANSWER-----------------Summing amp
What is the purpose of a power supply? ---------CORRECT ANSWER-------- ---------To convert AC power into smooth DC power What does the input of a power supply do? ---------CORRECT ANSWER---- -------------Step up or down the AC input voltage What does the rectifier do in a power supply? ---------CORRECT ANSWER- ----------------Changes AC into pulsating DC What does the filter do in a power supply? ---------CORRECT ANSWER----- ------------Changes pulsating DC into smooth DC How type of components do filters use? ---------CORRECT ANSWER--------- --------Reactive components What does a regulator do in a power supply? ---------CORRECT ANSWER-- ---------------maintains the output voltage at a constant level despite changes in load current What does the protection circuit do in power supply? ---------CORRECT ANSWER-----------------Prevents damage to power supply if load becomes faulty, limits or disables output
The half wave rectifier is the same as what circuit? ---------CORRECT ANSWER-----------------Series limiter Which rectifier is the least efficient using only half the input? --------- CORRECT ANSWER-----------------Half-wave Which two rectifiers require two input signals 180 degrees out of phase? --- ------CORRECT ANSWER-----------------Full-wave and bridge Which rectifier uses a center tapped transformer? ---------CORRECT ANSWER-----------------Full wave How is frequency determined for half wave rectifier? ---------CORRECT ANSWER-----------------Output frequency is same as input frequency How is frequency determined for full wave rectifier? ---------CORRECT ANSWER-----------------Output is twice the input frequency How is frequency determined for bridge rectifier? ---------CORRECT ANSWER-----------------Output is twice the input frequency What is the purpose of series voltage regulators? ---------CORRECT ANSWER-----------------To adjust voltage drop to maintain V out at constant level
In parallel voltage regulator, V out decreases when what happens? --------- CORRECT ANSWER-----------------When DC input decreases or load current increases What makes a zener diode different from junction diode? ---------CORRECT ANSWER-----------------Zener diode is designed operate in breakdown When does zener diode conduct reverse current? ---------CORRECT ANSWER-----------------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? ---------CORRECT ANSWER-----------------0.7V When reverse biased lower than Vz, what happens to zener diode? --------- CORRECT ANSWER-----------------Acts like an open If reverse biased lower than Vz, what is output voltage of shunt regulator? - --------CORRECT ANSWER-----------------Output is applied voltage When reverse biased higher than Vz, what is the output voltage of shunt regulator? ---------CORRECT ANSWER-----------------Vz Which component changes resistances to maintain constant V out (zener diode regulator)? ---------CORRECT ANSWER-----------------Q
Which component sets output voltage (zener diode regulator)? --------- CORRECT ANSWER-----------------D1 (holds Q1 at Vz) The voltage on emitter is established by what in zener diode regulator? ----- ----CORRECT ANSWER-----------------Action of Q If voltage increases what must happen to keep output voltage constant (zener diode regulator)? ---------CORRECT ANSWER-----------------Q collector-emitter resistance must increase If voltage decreases what must happen to keep output voltage constant (zener diode regulator)? ---------CORRECT ANSWER-----------------Q collector-emitter resistance must decrease In a voltage regulator, which component maintains a constant V out? --------
- CORRECT ANSWER-----------------Q In a voltage regulator, which components set voltage? ---------CORRECT ANSWER-----------------D1 and Q What does R2 do in voltage regulator? ---------CORRECT ANSWER---------- -------Varies conduction of Q2 (changes Vce)
What two conditions cause Vout to DECREASE in voltage regulator? --------
- CORRECT ANSWER-----------------Input voltage decreases or load current increases What are the most common faults in voltage regulators? ---------CORRECT ANSWER-----------------Semiconductor components (transistors/diodes) In a zener diode regulator, which faults cause output voltage to approach applied voltage? ---------CORRECT ANSWER-----------------D1 open, Short between Collector-Emitter In zener diode regulator, which faults cause output voltage to be 0V? --------
- CORRECT ANSWER-----------------D1 short/R1 Open, open between Base- Emitter Which fault in zener diode regulation can damage diode? --------- CORRECT ANSWER-----------------R1 short How do you calculate base voltage of Q1 in voltage regulator? --------- CORRECT ANSWER-----------------Vz + Vce = Vb Which fault in zener diode /voltage regulator causes Q1 base voltage to increase and approach saturation? ---------CORRECT ANSWER--------------- --D1 Open
Which fault in zener diode / voltage regulator causes Q1 base voltage to decreases and approach cutoff? ---------CORRECT ANSWER----------------- D1 short (no output volts) Which faults cause output voltage to approach applied volts in voltage regulator? ---------CORRECT ANSWER-----------------D1 open, R1 short, Q short Collector-Emitter Which faults cause output voltage to be 0V in voltage regulator? --------- CORRECT ANSWER-----------------R1 open, open Q1 base-emitter Which faults cause output voltage to decrease in voltage regulator? --------- CORRECT ANSWER-----------------D1 short, Q2 short What are two benefits of IC regulators? ---------CORRECT ANSWER--------- --------Safe/durable (thermal overload protection/current limiting protection) A constant 12 VDC output is maintained when input is between what values? (IC regulator) ---------CORRECT ANSWER-----------------14.5-30V What is max current output in 7812 IC regulator? ---------CORRECT ANSWER-----------------1.5A (RL never below 8 ohms) What is the purpose of unijunction transistors? ---------CORRECT ANSWER-----------------Switch voltage, turn on when input exceeds specific level
What happens when gate current is removed in SCR? ---------CORRECT ANSWER-----------------Nothing, diode is latched on How is SCR turned off? ---------CORRECT ANSWER-----------------Current flow must be interrupted with switch or by shorting anode to cathode What is the range of trigger currents in SCR? ---------CORRECT ANSWER- ----------------2mA to 20mA What is a purpose of relays? ---------CORRECT ANSWER----------------- Used for applying power to circuits or controlling signal flow What are two benefits of relays? ---------CORRECT ANSWER----------------- Can handle higher levels of current, make large power transfers possible How are relays shown on schematics? ---------CORRECT ANSWER---------- -------De-Energized Saying contacts are normally closed or normally open refers to them in which state? ---------CORRECT ANSWER-----------------De-energized What are 4 parts of relay? ---------CORRECT ANSWER----------------- magnetic coil, contacts, armature, spring
What replaces armature in multipole relays? ---------CORRECT ANSWER--- --------------Clapper and push rod What is one type of time delay relay? ---------CORRECT ANSWER------------ -----Bimetallic thermal relay
