ATT Test EXAM Questions AND CORRECT VERIFIED ANSWERS

ATT Test EXAM Questions AND CORRECT VERIFIED ANSWERS What is the purpose of parallel voltage regulator? - ANSWER -Adjust current flow to maintain V out at constant level In parallel voltage regulator, V out increases when what happens? - ANSWER DC input increases or load current decreases In parallel voltage regulator, V out decreases when what happens? - ANSWER When DC input decreases or load current increases What makes a zener diode different from junction diode? - ANSWER -Zener diode is designed operate in breakdown When does zener diode conduct reverse current? - 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? - ANSWER -0.7V When reverse biased lower than Vz, what happens to zener diode? - ANSWER Acts like an open If reverse biased lower than Vz, what is output voltage of shunt regulator? - ANSWER -Output is applied voltage When reverse biased higher than Vz, what is the output voltage of shunt regulator? - ANSWER -Vz Which component changes resistances to maintain constant V out (zener diode regulator)? - ANSWER -Q1 Which component sets output voltage (zener diode regulator)? - ANSWER -D1 (holds Q1 at Vz) The voltage on emitter is established by what in zener diode regulator? - ANSWER -Action of Q1 If voltage increases what must happen to keep output voltage constant (zener diode regulator)? - ANSWER -Q1 collector-emitter resistance must increase If voltage decreases what must happen to keep output voltage constant (zener diode regulator)? - ANSWER -Q1 collector-emitter resistance must decrease In a voltage regulator, which component maintains a constant V out? - ANSWER -Q1 In a voltage regulator, which components set voltage? - ANSWER -D1 and Q2 What does R2 do in voltage regulator? - ANSWER -Varies conduction of Q2 (changes Vce) If input voltage increases in voltage regulator, Q2 must do what to maintain constant output? - ANSWER -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? - ANSWER -Decrease resistance to drop less voltage (voltage of Q2 decrease) If load current increases in voltage regulator, how is base to emitter biasing affected? - ANSWER -FB increases If load current decreases in voltage regulator, how is base to emitter biasing affected? - ANSWER -FB decreases If load current increases in voltage regulator what needs to be done to maintain constant output? - ANSWER -Decrease resistance to drop less voltage If load current increases in voltage regulator, what needs to be done to maintain constant output? - ANSWER -Decrease resistance to drop less volts What two conditions cause Vout to INCREASE in voltage regulator? - ANSWER -Input voltage increases or load current decreases What two conditions cause Vout to DECREASE in voltage regulator? - ANSWER -Input voltage decreases or load current increases What are the most common faults in voltage regulators? - ANSWER Semiconductor components (transistors/diodes) In a zener diode regulator, which faults cause output voltage to approach applied voltage? - ANSWER -D1 open, Short between Collector-Emitter In zener diode regulator, which faults cause output voltage to be 0V? - ANSWER -D1 short/R1 Open, open between Base-Emitter Which fault in zener diode regulation can damage diode? - ANSWER -R1 short How do you calculate base voltage of Q1 in voltage regulator? - ANSWER -Vz + Vce = Vb How type of components do filters use? - ANSWER -Reactive components What does a regulator do in a power supply? - ANSWER -maintains the output voltage at a constant level despite changes in load current What does the protection circuit do in power supply? - ANSWER -Prevents damage to power supply if load becomes faulty, limits or disables output The half wave rectifier is the same as what circuit? - ANSWER -Series limiter Which rectifier is the least efficient using only half the input? - ANSWER -Half wave Which two rectifiers require two input signals 180 degrees out of phase? - ANSWER -Full-wave and bridge Which rectifier uses a center tapped transformer? - ANSWER -Full wave How is frequency determined for half wave rectifier? - ANSWER -Output frequency is same as input frequency How is frequency determined for full wave rectifier? - ANSWER -Output is twice the input frequency How is frequency determined for bridge rectifier? - ANSWER -Output is twice the input frequency What is the purpose of series voltage regulators? - ANSWER -To adjust voltage drop to maintain V out at constant level In a series voltage regulator, V out INCREASES when what happens? - ANSWER -Load current decreases OR DC input increases