ATT TEST 7 EXAM LATEST 2024 ACTUAL EXAM 150
QUESTIONS AND CORRECT DETAILED ANSWERS
WITH RATIONALES (VERIFIED ANSWERS)
|ALREADY GRADED A
Base one to emitter current flows. <<ANSWER :A UJT is ON when (____________.)
The SCR remains on. <<ANSWER :What happens to an SCR when it is turned on and
gate current is removed?
Change DC power to AC power. <<ANSWER :The purpose of a UJT oscillator is
to_________.
RC time constant. <<ANSWER :The operation of a basic UJT oscillator is based
on______.
Stopping or reducing anode current. <<ANSWER :An SCR is turned off by________.
2.1 Volts DC <<ANSWER :The average voltage applied to a load when the input
voltage has a RMS value of 25 volts and the SCR has a conduction angle of 30 degrees
is______.
SCR. <<ANSWER :The most common fault in a SCR circuit is the ______.
Pulsating DC <<ANSWER :Current that varies in amplitude but does not reverse
polarity `Not alt. Current because polarity remains the same
Protection. <<ANSWER :Optional section in an scr power supply. Prevents damage to
power supply from excess current flow
AC to DC <<ANSWER :Diode reflecters
Power Supply <<ANSWER :AC to DC
Half Wave Diode Reflector <<ANSWER :AC to DC
(VDC=VPeak of secondary x .318)
Full Wave Diode Rectifier <<ANSWER :AC to DC
VAVG= [VPP/2] x .636
If center tapped:
VAVG= [VPP/4] x .636
Diodes preform reflection
180° out of phase
Bridge Diode Rectifier <<ANSWER :Only conducts if forward biased
, (VAVG= VPEAK x .636)
Output: pulsating DC
Half Wave rectifier freq <<ANSWER :Ripple req: same as input freq
Full wave rectifier freq <<ANSWER :Ripple freq: twice input freq
With half VPEAK output
Bridge rectifier freq <<ANSWER :Ripple freq: twice input freq
Output: twice the voltage of a fullwave
Applied voltage is taken across the full potential of the transformer <<ANSWER
:Advantage of a Bridge vs Fullwave
Voltage regulators purpose <<ANSWER :Adjust voltage to maintain Eout at a constant
level
Zener diode normal operation <<ANSWER :Fwd biased: low ohms
Rev biased: high ohms
Zener diode <<ANSWER :Series voltage regulator
Efficiency of a full wave vs half wave <<ANSWER :Full wave is more efficient because
an output is developed for entire wave form
Purpose of a series volt regulator <<ANSWER :Maintain constant output voltages to a
load
series volt regulator <<ANSWER :Load current increases, r1 square root = er square
root
Eout increases, DC increases (OR current of load square rooted) <<ANSWER :In a
Parallel volt regulator...
rev bias Zener Diode <<ANSWER :Rev bias when anode (+) is more - than cathode (-)
In a zener reg.. Q1 Fwd bias increases when ___ ___ ___. <<ANSWER :load current
increases
Q1 maintains output voltage level <<ANSWER :In a variable volt regulator...
input V increases, Q1s voltage increases <<ANSWER :In a variable volt regulator...
reverse biasing an SCR with a multimeter <<ANSWER :Put meters negative port on
anode
QUESTIONS AND CORRECT DETAILED ANSWERS
WITH RATIONALES (VERIFIED ANSWERS)
|ALREADY GRADED A
Base one to emitter current flows. <<ANSWER :A UJT is ON when (____________.)
The SCR remains on. <<ANSWER :What happens to an SCR when it is turned on and
gate current is removed?
Change DC power to AC power. <<ANSWER :The purpose of a UJT oscillator is
to_________.
RC time constant. <<ANSWER :The operation of a basic UJT oscillator is based
on______.
Stopping or reducing anode current. <<ANSWER :An SCR is turned off by________.
2.1 Volts DC <<ANSWER :The average voltage applied to a load when the input
voltage has a RMS value of 25 volts and the SCR has a conduction angle of 30 degrees
is______.
SCR. <<ANSWER :The most common fault in a SCR circuit is the ______.
Pulsating DC <<ANSWER :Current that varies in amplitude but does not reverse
polarity `Not alt. Current because polarity remains the same
Protection. <<ANSWER :Optional section in an scr power supply. Prevents damage to
power supply from excess current flow
AC to DC <<ANSWER :Diode reflecters
Power Supply <<ANSWER :AC to DC
Half Wave Diode Reflector <<ANSWER :AC to DC
(VDC=VPeak of secondary x .318)
Full Wave Diode Rectifier <<ANSWER :AC to DC
VAVG= [VPP/2] x .636
If center tapped:
VAVG= [VPP/4] x .636
Diodes preform reflection
180° out of phase
Bridge Diode Rectifier <<ANSWER :Only conducts if forward biased
, (VAVG= VPEAK x .636)
Output: pulsating DC
Half Wave rectifier freq <<ANSWER :Ripple req: same as input freq
Full wave rectifier freq <<ANSWER :Ripple freq: twice input freq
With half VPEAK output
Bridge rectifier freq <<ANSWER :Ripple freq: twice input freq
Output: twice the voltage of a fullwave
Applied voltage is taken across the full potential of the transformer <<ANSWER
:Advantage of a Bridge vs Fullwave
Voltage regulators purpose <<ANSWER :Adjust voltage to maintain Eout at a constant
level
Zener diode normal operation <<ANSWER :Fwd biased: low ohms
Rev biased: high ohms
Zener diode <<ANSWER :Series voltage regulator
Efficiency of a full wave vs half wave <<ANSWER :Full wave is more efficient because
an output is developed for entire wave form
Purpose of a series volt regulator <<ANSWER :Maintain constant output voltages to a
load
series volt regulator <<ANSWER :Load current increases, r1 square root = er square
root
Eout increases, DC increases (OR current of load square rooted) <<ANSWER :In a
Parallel volt regulator...
rev bias Zener Diode <<ANSWER :Rev bias when anode (+) is more - than cathode (-)
In a zener reg.. Q1 Fwd bias increases when ___ ___ ___. <<ANSWER :load current
increases
Q1 maintains output voltage level <<ANSWER :In a variable volt regulator...
input V increases, Q1s voltage increases <<ANSWER :In a variable volt regulator...
reverse biasing an SCR with a multimeter <<ANSWER :Put meters negative port on
anode
