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I need the last 14 pennfoster Electronics Technician exams

Customer Question

I need the last 14 pennfoster Electronics Technician exams answers they are (1)08603901 (2)00290901 (3)2703C (4)2708A(5)2708B (6)2709A (7)2709B (8)2710A (9)2710B (10)2711A (11)2711B (12)2711C (13)2712A and (14)2712B....thank you
Submitted: 1 year ago.
Category: Homework
Expert:  akch2002 replied 1 year ago.
I may help you with some of these exams if you upload the questions here and you will have to rate each exam's answer separately.
Customer: replied 1 year ago.

how can i upload a file the questions are to big ?

Customer: replied 1 year ago.

Hello please can you help me most justanswer homework all you have to do is give them the exams number and they have the answers i can't upload the questions it to large please i need the answers soon as posibble...thank you

Expert:  akch2002 replied 1 year ago.

I don't have access to the questions. Hence, I need questions to reply. You can upload one set of questions at one time. Once it has been answered, you can proceed to the next one.

Customer: replied 1 year ago.


Hello can you help me at lease with some of yhe exam answers?....thank you

Expert:  akch2002 replied 1 year ago.
If I get the questions, I may help you.
Expert:  akch2002 replied 1 year ago.
Justanswer.com has forwarded some questions files to me. I will go through them and will upload the answers asap. Thanks.
Expert:  akch2002 replied 1 year ago.
Here are answers for 2703C.
1.B
2.D
3.A
4.D not sure
5.C
6.C
7.B
8.B
9.B
10.C
11.B
12.C
13.A
14.B
15.C

Kindly rate these answers. BONUS will be appreciated.
akch2002, Engineer
Category: Homework
Satisfied Customers: 2802
Experience: Home work expert
akch2002 and other Homework Specialists are ready to help you
Customer: replied 1 year ago.

Would like to move on the the next one great work....thank you

Expert:  akch2002 replied 1 year ago.

Thanks.
I was not sure about 4 but why 6 went wrong. I will look into it.
Do you have any text material for these exams? If, yes; kindly upload.

I will look into other exams and will try to upload the answers asap.

Customer: replied 1 year ago.

akch2002 here is another exam question's thank you ---2708A
Pulse Circuits
When you feel confident that you have mastered the material in this study unit, complete
the following examination. Then submit only your answers to School Headquarters for
grading, using one of the examination answer options described in your first shipment. Send
your answers for this examination as soon as you complete it. Do not wait until another
examination is ready.
Questions 1-25: Select the one best answer to each question.
1. What would be the time constant in an RC circuit when R = 200 kn and C = 10 f.lF?
A. 20 sec C. 2 sec
B. 5 sec D. 0.5 sec
2. Which of the output waveforms is correct for the input signal shown?
INPUT SIGNAL
A. B.
c.IJ D.
3. When a pulse is amplified in a linear amplifier, the charge carrier transmit time can
cause
A. loss of the d-e reference levels.
B. rise-time distortion.
C. waveform tilt.
D. propagation delay.
4. It requires 5 time divisions for a pulse to go from 10% to 90% of full amplitude. The
sweep of the scope is calibrated so that 10 f.lSec are represented by 20 divisions. What
is the rise time of the pulse?
A. 0.25 p.sec C. 10 p.sec
B. 2.5 p.sec D. 15 p.sec
5. In a certain LR time constant circuit, it takes 135 msec for the current to reach
maximum after the switch is closed. If the inductance is 4 henrys, what is the value
of circuit resistance?
A. 670 n
B. 148 n
3
c. 0.670 n
D. o.l48 n 6. When you increase the width of a pulse, you
A. decrease average value. C. increase overshoot.
B. decrease duty cycle. D. increase RMS value.
7. Which of the following will most likely cause arcing at the switch contacts?
A. A switch that starts current flowing in an LR time constant circuit
B. A switch that opens an LR time constant circuit
C. A switch that starts the capacitor charge in an RC time constant circuit
D. A switeh--that opens an R-b'-time constant circuit fer ihe capacitor to discharge
8. In a certain circuit the output signal is NOT permitted to exceed a certain value
even though the input signal tries to drive it beyond that value. What is the circuit?
A. Limiter C. Baseline stabilizer
B. Clipper D. Ringing oscillator
9. How would you describe a differentiator?
A. An RC circuit where the time constant is greater than 1.
B. An RC circuit where the time constant is equal to 1.
C. A circuit that has an output signal proportional to the sum of input pulses.
D. A circuit that has an output signal proportional to the rate of change of the
input signal.
10. Of the following devices, which one is most suitable for frequency domain displays?
A. Memory scope C. Spectrum analyzer
B. Oscillograph D. Triggered sweep scope
11. An NPN common emitter transistor, when operated without d-e bias, can be used as a
A. d-e restorer. C. positive peak clipper.
B. negative peak clipper. D. baseline stabilizer.
12. The amplifier circuit shown uses an enhancement-type N-channel MOSFET. The input
signal goes from a slightly positive value to a negative value, then back to a slightly
positive value. Which waveform is correct for the output signal?
ov-uINPUT
SIGNAL
4
A. __.n.____
B.
c.
D. 13. What is the bandwidth of an amplifier that produces a square wave with a rise time
of 2 p.sec?
A. 20kHz C. 70kHz
B. 57 kHz D. 175kHz
14. An advantage of direct-coupled amplifiers is that they
A. make ideal clippers.
B. make ideal limiters.
C. can amplify a signal without inverting it.
D. can amplify a signal without changing its d-e reference level.
15. Determine the duty cycle for the pulse shown below.
A. 9%
B. 23%
c. 27%
D. 80%
1--- 22.5 p.sec ---1
16. When a pulse is delivered to an amplifier, ringing may occur if
A. the amplifier is overdriven.
B. direct coupling is used.
C. there is inductance in the output circuit.
D. the amplifier is operated without bias.
17. To transmit only portions of an input wave lying on one side of an amplitude
boundary, you would use a
A. toggled flip flop. C. limiter.
B. d-e restorer. D. clipper.
18. When working with pulse generators, you should be aware that a monostable multi,
vibrator is also a(n)
A. collector-coupled multivibrator. C. astable multivibrator.
B. one-shot multivibrator. D. bilateral compressor.
19. How long will it take for the current to reach 36.7% of its initial value in an inductive
discharge circuit if R equals 1000 n and L equals 4 henrys?
A. 40 sec C. 0.004 sec
B. 10 sec D. 0.001 sec
5 20. An oscilloscope grid is calibrated so that one square represents 1-V vertically and 1 msec
horizontally. If the height of a square wave pulse display is 6 squares, the width of the
pulse is 7 squares, and the cycle of the wave is 16 squares, the average value of the
pulse is
A. 1.73 V.
B. 2.63 v.
c. 3.97 v.
D. 4.32 V.
21. To change the relationship between a waveform and the zero-volt axis, and at the same
time retain the shape of the wave, you would use a
A. toggled flip flop. C. limiter.
B. d-e restorer. D. clipper.
22. Which one of the following actions will you take to decrease the rise time of pulses
passing through an amplifier?
A. Increase low-frequency response.
B. Decrease low-frequency response.
C. Increase high-frequency response.
D. Decrease high-frequency response.
23. The simplest clamping circuit consists of a
A. diode and capacitor. C. capacitor and resistor.
B. diode and resistor. D. capacitor and inductor.
24. If the pulse repetition rate (PRR) of a transmitted pulse is 400 pulses per second, what
is the period of the waveform?
A. 2.5 msec C. 25 msec
B. 4.0 msec D. 40 msec
25. The time that it takes for a capacitor to completely charge or discharge is, for all
practical purposes, equal to time constants.
A. two C. four
B. three D. five

Expert:  akch2002 replied 1 year ago.
I will try to complete it today. If you have some reference material pertaining to these questions, kindly upload. Thanks.
Customer: replied 1 year ago.


Ok thank you

Expert:  akch2002 replied 1 year ago.
You are most welcome.
Customer: replied 1 year ago.

This is also one of the exams question...thank you


 


EXAMINATION
27088
Pulse Circuits
When you feel confident that you have mastered the material in this study unit, complete
the following examination. Then submit only your answers to School Headquarters for
grading, using one ofthe examination answer options described in your first shipment. Send
your answers for this examination as soon as you complete it. Do not wait until another
examination is ready.
Questions 1-25: Select the one best answer to each question.
1. Which one of the following resistance-capacitance combinations has the longest time
constant?
A. R = 0.089 MD; C = 0.09 pF C. R = 82 kQ; C = 27,000 pF
B. R = 75 kQ; C = 0.3 pF D. R = 88,000 n; C = 0.15 JJ.F
2. Which one of the following statements is characteristic of the output pulse of a 555
monostable multivibrator? (Assume a positive trigger pulse.)
A. The output pulse ends when the trigger pulse ends.
B. The output pulse ends when the trigger pulse starts.
C. The output pulse starts when the trigger pulse ends.
D.- The output pulse starts when the trigger pulse starts.
3. Which one of the following conditions must you avoid when you use a logic pulser to
troubleshoot a sine-wave-operated digital clock?
A. Two logic 0 levels at the same point in the circuit
B. Two logic 1 levels at the same point in the circuit
C. Two logic signals in phase at the same point in the circuit
D. Two logic signals out of phase at the same point in the circuit
4. To obtain the greatest possible accuracy in a timing device, you should use a
A. digital timer operated from a crystal-controlled oscillator.
B. 3905 IC operated through an electronic inductor.
C. timer with a unijunction transistor in its circuit.
D. 555 IC operated through an electronic capacitor.
Question 5 is based on the following schematic of an astable-multivibrator.
Sk!l
15 k !l
SSSIC
9 5. In order to obtain a 0.5-msec discharge time in the multivibrator circuit, you will need
a capacitor rated at 11 F.
A. 0.14
B. 0.09
c. 0.07
D. 0.05
6. You have two methods of locating faults in electronic systems - signal tracing and
signal
A. dumping. C. shaping.
B. injecting. D. squaring.
7. A disadvantage of timers operated by an RC time constant circuit is that efficient
operation
A. requires long timing periods.
B. requires a high input power.
C. depends on maintaining a constant temperature.
D. depends on maintaining a minimum 15-V input.
8. You use a square-wave test to determine if an amplifier is functioning properly. This
test may NOT be conclusive if the amplifier is
A. operating in an overdriven mode.
B. acting as an emitter follower.
C. displaying poor low-frequency response.
D. looking into a resistive load.
Question 9 is based on the following schematic.
9. The output of the circuit will be a high when
A
A. A, B, and Care high.
B. A, B, and Care low.
C. A is low and B and C are high.
D. A is high and B and C are low.
10. Which one of the following distinguishes a switching power supply from other power
suppliers?
A. Simpler circuitry C. Higher output voltage
B. Smaller transformer D. Elimination of diode rectifier
11. Which of the following devices is connected internally to an output pin of a 555 IC?
A. RS flip-flop C. Reset transistor
B. Power amplifier D. Threshold comparator
10 Question 12 is based on the following graph.
12. Using the time delay graph, determine the approximate capacitance needed with a
10,000 n resistance to obtain a 10-msec delay with· a 555 monostable multivibrator.
A. 0.008 ,uF
TIME DELAY VERSUS RAND C
100
B. 0.08 ,uF
C. 0.8 ,uF 10
D. 8 ,uF ...
w
"'
u
z
<(
...
u
<( 0.1
11.
<(
u
O.Ql
0.001 L...L...---L..L...----1-..__~'---'---'----:'
10 100 1 10 1 10
"'sec ,. sec maec: msec maec sec sec
TIME DELAY
13. In troubleshooting a pulse circuit by waveform comparison, you should use
A. a logic probe. C. an oscilloscope.
B. a logic scope. D. a pulser.
14. Which one of the following probe circuits will activate the LED when the probe touches
a logic 0?
+
A.~
+
c.~
B.~ D.~
Question 15 is based on the following schematic.
I
15. When the switch in the circuit has just closed, which one of the following waveforms
will occur at output A? (Note: Under the conditions shown in the schematic, the
capacitor is not charged. )
A./ B. /c.\__ D. L
11 16. The most convenient and least time-consuming method of determining an amplifier's
ability to pass a pulse in a digital circuit is to use the
A. sine-wave test. C. VOM test.
B. square-wave test. D. Wattmeter test.
17. "An output of a high from a logic gate having a high on only one input" describes the
operation of
A. an AND gate. C. an NOR gate.
B. a NOT gate. D. ah XOR gate.
18. A one-shot multivibrator contains two transistors. What is the condition of the
transistors in the standby state?
A. Input transistor is cut off; output transistor is saturated.
B. Output transistor is cut off; input transistor is saturated.
C. Both transistors are saturated.
D. Both transistors are cut off.
19. You would use a logic analyzer to test
A. voltage values. C. an ac amplifier.
B. a digital integrated circuit. D. a system's power supply.
20. When you hold down the switch in most types of pulsers, the instrument will generate a
A. clock waveform. C. single pulse.
B. sine wave. D. triangular wave.
21. The input trigger pulse to the 3905 timer must be
A. negative-going to pin 1. C. negative-going to pin 2.
B. positive-going to pin 1. D. positive-going to pin 2.
22. Which one of the following testing methods should you use in comparing the power
requirements of several different computer systems?
A. Benchmark testing C. Logic probing
B. Component-by-component testing D. Signal tracing
23. Which one of the following changes in resistance and capacitance will produce the
shortest pulse width in a 555 one-shot multivibrator?
A. Decrease resistance and increase capacitance.
B. Increase resistance and decrease capacitance.
C. Decrease both resistance and capacitance.
D. Increase both resistance and capacitance.
24. The reason for connecting a diode across the resistor in the trigger circuit of a 555
monostable multivibrator is to
A. rectify the trigger circuit d-e supply.
B. give a sharper rise time to the trigger pulse.
C. prevent a negative voltage from entering the comparator.
D. lower the cost of the system by substituting a cheap diode for an expensive
resistor.
12 25. Which one of the following testing devices should you use in checking the power
supply for a digital system in which the value of logic 1 CANNOT vary by more
than 0.5%?
A. Logic scope C. Voltmeter
B. Pulser D. Wattmeter
13

Expert:  akch2002 replied 1 year ago.
I will try these questions also. Thanks.
Expert:  akch2002 replied 1 year ago.
I am not sure about some of the questions in both sets of questions and, hence, I will opt out.
Customer: replied 1 year ago.

Well i understand i will take what you got...thank you

Expert:  akch2002 replied 1 year ago.
Should I reply about which I am sure.
Customer: replied 1 year ago.

yea sure thanks

Expert:  akch2002 replied 1 year ago.
I will upload the answers later today. Thanks.
Customer: replied 1 year ago.


Ok thank you

Expert:  akch2002 replied 1 year ago.
THIS ANSWER IS LOCKED!
You can view this answer by clicking here to Register or Login and paying $3.
If you've already paid for this answer, simply Login.
Customer: replied 1 year ago.

akch2002 i got a 65 score thanks most of the answers you enter was correct and the others that i enter was incorrect thanks again great job

Expert:  akch2002 replied 1 year ago.
Actually I can comfortably reply electrical questions. I have idea about Electronics questions but these require study. I don't have books; hence, I can't study and reply.
Customer: replied 1 year ago.


ok


 

Expert:  akch2002 replied 1 year ago.
No problem. Kindly upload if any electrical questions are there.
Customer: replied 1 year ago.

akch2002 this is one of the exams i need help with thank you


EXAMINATION
27088
Pulse Circuits
When you feel confident that you have mastered the material in this study unit, complete
the following examination. Then submit only your answers to School Headquarters for
grading, using one ofthe examination answer options described in your first shipment. Send
your answers for this examination as soon as you complete it. Do not wait until another
examination is ready.
Questions 1-25: Select the one best answer to each question.
1. Which one of the following resistance-capacitance combinations has the longest time
constant?
A. R = 0.089 MD; C = 0.09 pF C. R = 82 kQ; C = 27,000 pF
B. R = 75 kQ; C = 0.3 pF D. R = 88,000 n; C = 0.15 JJ.F
2. Which one of the following statements is characteristic of the output pulse of a 555
monostable multivibrator? (Assume a positive trigger pulse.)
A. The output pulse ends when the trigger pulse ends.
B. The output pulse ends when the trigger pulse starts.
C. The output pulse starts when the trigger pulse ends.
D.- The output pulse starts when the trigger pulse starts.
3. Which one of the following conditions must you avoid when you use a logic pulser to
troubleshoot a sine-wave-operated digital clock?
A. Two logic 0 levels at the same point in the circuit
B. Two logic 1 levels at the same point in the circuit
C. Two logic signals in phase at the same point in the circuit
D. Two logic signals out of phase at the same point in the circuit
4. To obtain the greatest possible accuracy in a timing device, you should use a
A. digital timer operated from a crystal-controlled oscillator.
B. 3905 IC operated through an electronic inductor.
C. timer with a unijunction transistor in its circuit.
D. 555 IC operated through an electronic capacitor.
Question 5 is based on the following schematic of an astable-multivibrator.
Sk!l
15 k !l
SSSIC
9 5. In order to obtain a 0.5-msec discharge time in the multivibrator circuit, you will need
a capacitor rated at 11 F.
A. 0.14
B. 0.09
c. 0.07
D. 0.05
6. You have two methods of locating faults in electronic systems - signal tracing and
signal
A. dumping. C. shaping.
B. injecting. D. squaring.
7. A disadvantage of timers operated by an RC time constant circuit is that efficient
operation
A. requires long timing periods.
B. requires a high input power.
C. depends on maintaining a constant temperature.
D. depends on maintaining a minimum 15-V input.
8. You use a square-wave test to determine if an amplifier is functioning properly. This
test may NOT be conclusive if the amplifier is
A. operating in an overdriven mode.
B. acting as an emitter follower.
C. displaying poor low-frequency response.
D. looking into a resistive load.
Question 9 is based on the following schematic.
9. The output of the circuit will be a high when
A
A. A, B, and Care high.
B. A, B, and Care low.
C. A is low and B and C are high.
D. A is high and B and C are low.
10. Which one of the following distinguishes a switching power supply from other power
suppliers?
A. Simpler circuitry C. Higher output voltage
B. Smaller transformer D. Elimination of diode rectifier
11. Which of the following devices is connected internally to an output pin of a 555 IC?
A. RS flip-flop C. Reset transistor
B. Power amplifier D. Threshold comparator
10 Question 12 is based on the following graph.
12. Using the time delay graph, determine the approximate capacitance needed with a
10,000 n resistance to obtain a 10-msec delay with· a 555 monostable multivibrator.
A. 0.008 ,uF
TIME DELAY VERSUS RAND C
100
B. 0.08 ,uF
C. 0.8 ,uF 10
D. 8 ,uF ...
w
"'
u
z
<(
...
u
<( 0.1
11.
<(
u
O.Ql
0.001 L...L...---L..L...----1-..__~'---'---'----:'
10 100 1 10 1 10
"'sec ,. sec maec: msec maec sec sec
TIME DELAY
13. In troubleshooting a pulse circuit by waveform comparison, you should use
A. a logic probe. C. an oscilloscope.
B. a logic scope. D. a pulser.
14. Which one of the following probe circuits will activate the LED when the probe touches
a logic 0?
+
A.~
+
c.~
B.~ D.~
Question 15 is based on the following schematic.
I
15. When the switch in the circuit has just closed, which one of the following waveforms
will occur at output A? (Note: Under the conditions shown in the schematic, the
capacitor is not charged. )
A./ B. /c.\__ D. L
11 16. The most convenient and least time-consuming method of determining an amplifier's
ability to pass a pulse in a digital circuit is to use the
A. sine-wave test. C. VOM test.
B. square-wave test. D. Wattmeter test.
17. "An output of a high from a logic gate having a high on only one input" describes the
operation of
A. an AND gate. C. an NOR gate.
B. a NOT gate. D. ah XOR gate.
18. A one-shot multivibrator contains two transistors. What is the condition of the
transistors in the standby state?
A. Input transistor is cut off; output transistor is saturated.
B. Output transistor is cut off; input transistor is saturated.
C. Both transistors are saturated.
D. Both transistors are cut off.
19. You would use a logic analyzer to test
A. voltage values. C. an ac amplifier.
B. a digital integrated circuit. D. a system's power supply.
20. When you hold down the switch in most types of pulsers, the instrument will generate a
A. clock waveform. C. single pulse.
B. sine wave. D. triangular wave.
21. The input trigger pulse to the 3905 timer must be
A. negative-going to pin 1. C. negative-going to pin 2.
B. positive-going to pin 1. D. positive-going to pin 2.
22. Which one of the following testing methods should you use in comparing the power
requirements of several different computer systems?
A. Benchmark testing C. Logic probing
B. Component-by-component testing D. Signal tracing
23. Which one of the following changes in resistance and capacitance will produce the
shortest pulse width in a 555 one-shot multivibrator?
A. Decrease resistance and increase capacitance.
B. Increase resistance and decrease capacitance.
C. Decrease both resistance and capacitance.
D. Increase both resistance and capacitance.
24. The reason for connecting a diode across the resistor in the trigger circuit of a 555
monostable multivibrator is to
A. rectify the trigger circuit d-e supply.
B. give a sharper rise time to the trigger pulse.
C. prevent a negative voltage from entering the comparator.
D. lower the cost of the system by substituting a cheap diode for an expensive
resistor.
12 25. Which one of the following testing devices should you use in checking the power
supply for a digital system in which the value of logic 1 CANNOT vary by more
than 0.5%?
A. Logic scope C. Voltmeter
B. Pulser D. Wattmeter

Expert:  akch2002 replied 1 year ago.
Sorry, I won't be able to help with these questions.
Customer: replied 1 year ago.

I need the last 12 pennfoster Electronics Technician exams answers they are
(2)00290901 (4)2708A(5)2708B (6)2709A (7)2709B (8)2710A (9)2710B (10)2711A
(11)2711B (12)2711C (13)2712A and (14)2712B i need the price and the answers
....thank you

Expert:  akch2002 replied 1 year ago.
Kindly upload the questions. to enable me to decide whether I can reply or not.
Customer: replied 1 year ago.

I need the answers for exam 00290901 answers can you help....thank you

Expert:  akch2002 replied 1 year ago.
After having a look on the questions, I can decide whether I can help you or not. Kindly upload the questions.
Customer: replied 1 year ago.

INTRODUCTION
Welcome to your ninth electronics practical exercise! The purpose of
this practical exercise is to help you apply your program learning to
some real-life situations. First, you’ll complete some suggested activities
that relate to the topics you’ve studied in this module. The suggested
activities are fun, hands-on activities you may want to try on your own.
These activities will enable you to learn more about electronic circuits,
components, and applications.
After you’ve read through the activities, we’ll present you with some
electronics scenarios and illustrations of common components and
equipment, and ask you to answer some questions about them. These
questions will be graded as an examination for your program.
Note that the suggested activities are optional—they aren’t required to
complete the program, and you won’t be graded on them. However,
because the suggested activities are designed to help you increase and
enhance your learning, we strongly recommend that you attempt to
complete as many of the activities as possible. The examination at the
end of the exercise is required and must be submitted to the school for
grading.
Now, when you’re ready, complete the practical exercise. Then, submit
only your answers to school headquarters for grading, using one of the
answer options described in your first shipment.
Remember that even though this exercise contains examination questions, we’ve designed it to be fun, challenging, and interesting. Applying your knowledge to real-life situations will help you realize how
much you’ve learned. It will be a rewarding experience that will give
you confidence in your newly acquired skills.
We hope you enjoy this practical exercise!
Practical Exercise 9
1SUGGESTED EXERCISES
It’s time to take a break and have some fun. The following are some
hands-on activities that you may want to try to enhance your learning.
None of these activities will be graded. However, these activities will
help you expand your practical understanding of electronics applications, troubleshooting techniques, and the on-the-job responsibilities
you’ll face as an electronics technician. We therefore recommend that
you read through the exercises in order to help you learn to apply your
electronics knowledge to some practical situations. At any time, you
can proceed to the graded portion of the practical exercise.
Activity 1
The purpose of this activity is to construct and demonstrate a switch
that responds to touch. In order to complete this activity, you’ll need a
low-wattage soldering iron, the desoldering device that was supplied
with an earlier module, and a 9 V battery. You’ll also need the components in the following list. At this time, locate the components in your
parts pack and check them off on the list.
Now, when you’re ready, work through the following steps to construct your touch switch. Figure 1 shows the location of the components
on the circuit board.
Step 1: Insert the eight-pin IC socket into the U1
position on the circuit board. Observe the position of the notch as you install
the socket. The notch on the socket should align with the
markings on the circuit board. Then, solder all eight pins to
the foil side of the board.
2 Practical Exercise 9
Description Quantity
Printed-circuit board 1
Eight-pin integrated-circuit socket 1
4.7 F electrolytic capacitor 2
Slide switch 1
0.01 F disc capacitor (labeled 103) 1
1.5 k resistor (brown-green-red) 1
22 k resistor (red-red-orange) 1
Red LED 1
Plastic instrument case 1
3 8 mm self-tapping screws 2
100 k potentiometer 1
555 integrated circuit 1
Length of hookup wire 1Step 2: Insert the power switch into the circuit board at the SW1
position. The switch may be inserted in either direction. Solder
the switch leads to the foil.
Step 3: Mount a 4.7 F electrolytic capacitor at the C1
position on the
board. (Note the position of the negative terminal.) Bend the
capacitor over on its side as shown in Figure 2 so that it lies
between the power switch and the eight-pin socket, and
make sure that the capacitor doesn’t cover hole C. Solder the
capacitor leads to the foil and clip off the excess lead lengths.
Practical Exercise 9 3
B A
R1
C3
BAT
BAT
C1
SPKR
SW 1
D
E
C
R3
J2
Q2
J1
C2
R2
F
MODEL
213
b
e
e
c
b c
U1
+

– +
– +
– +
+
RX/Q1
RED LEAD
FIGURE 1—This illustration
shows the locations of the
eight-pin integrated circuit
socket, the power switch
(SW1
), the 4.7 F electrolytic
capacitor, the 0.01 F disc
capacitor, the 1.5 k resistor, the 22 k resistor, and
the red LED on the circuit
board.

+
C1
FIGURE 2—Bend the
4.7 F electrolytic
capacitor over on its
side as shown here so
that it lies between the
power switch and the
eight-pin socket.Step 4: Mount a 0.01F disc capacitor (marked 103) to the C 3
position on the board. Solder the leads to the foil and clip off the
excess lead lengths.
Step 5: Mount a 1.5 k resistor (brown-green-red) at the R1
position
on the board. Solder the leads to the foil and clip off the excess lead lengths.
Step 6: Mount a 22 k resistor (red-red-orange) at the R2
position.
Solder the leads to the foil and clip off any excess lead
lengths.
Step 7: Next, you’ll mount the LED on the circuit board. Insert the
LED in the LED1
position on the circuit board. Observe the
position of the flat as shown in Figure 3, and spread the leads
slightly to hold the LED in place.
Step 8: The LED must be installed at a specific height off the circuit
board. This height is important because the completed board
will be mounted in the case supplied and the LED must protrude through the hole in the case.
In order to ensure that the LED is mounted properly, you’ll temporarily
mount the circuit board in the case at this time. Mount the circuit board
in the case, using two 3 × 8 mm self-tapping screws to hold it in place
as shown in Figure 4. Tighten the screws.
4 Practical Exercise 9
FLAT
CATHODE
FIGURE 3—When you
mount the LED on the circuit board, observe the
position of the flat as
shown here.Step 9: Gently push on the LED leads until the head of the LED protrudes through the hole in the front of the case. Solder the
LED leads to the foil.
Step 10: Remove the circuit board from the case and put the screws
aside for later use.
Step 11: Clip off any excess length from the LED leads.
Step 12: Mount a 4.7 F electrolytic capacitor to the C2
position on the
board. Solder the leads to the foil and clip off any excess lead
lengths.
Now, refer to Figure 5 as you work through the following step.
Step 13: Mount a 100 k potentiometer at the RX
/Q1
position on the
circuit board. Solder all three leads to the foil side of the
board.
Step 14: Cut a 1-inch length of hookup wire and strip 1
4
inch of insulation from each end of the wire.
Step 15: Insert one end of the 1-inch wire into hole A (shown in Figure 1)
and solder it to the foil. Clip off any excess lead length.
Practical Exercise 9 5
FIGURE 4—Temporarily
mount the circuit board
in the case using two
3 8 mm self-tapping
screws to hold it in place.Step 16: Insert the other end of the 1-inch wire into hole D and solder.
Clip off any excess lead length.
Step 17: Cut a 11
2
-inch length of hookup wire and strip 1
4
inch of insulation from each end of the wire.
Step 18: Insert one end of the 11
2
-inch wire into hole C, located near
pin 7 of U1
, as shown in Figure 1. (Note that this hole is labeled with an uppercase C.) Solder the lead to the foil, and
cut off any excess lead length.
Step 19: Insert the other end of the 11
2
-inch wire into hole c as shown
in Figure 6. (Note that this hole is labeled with a lowercase c.)
Solder the lead to the foil, and cut off any excess lead length.
Step 20: Cut another 11
2
-inch length of hookup wire and strip 1
4
inch
of insulation from each end.
6 Practical Exercise 9
FIGURE 5—This illustration
shows you how to mount
the 100 k potentiometer at the RX
/Q1
position
on the circuit board.
Q2
e
b
c
FIGURE 6—Insert one
end of this wire into hole
“c” as shown here.Step 21: Insert one end of the 11
2
-inch into hole E and solder (Figure 1).
Clip off any excess lead length.
Step 22: Leave the other end of the 11
2
-inch wire unconnected. This
end of the wire will be used as the probe for the touch sensor.
Step 23: Insert the IC into the socket at U1
as shown in Figure 1. Note
the position of the notch in the IC, on the same side of the
IC as pin 1, as shown in Figure 7. Insert the IC so the notch
aligns with the notch on the IC socket (that is, with pin 1
closest to the “U1” marking on the board).
Step 24: Carefully examine the foil side of the board for solder bridges
or unsoldered connections. Make sure that no excess lead
lengths are protruding from the foil.
Your touch switch circuit is now complete. This touch switch circuit is
actually a monostable multivibrator circuit, which means that the circuit
has one stable state. The monostable multivibrator (sometimes called a
one-shot) is used to produce an output pulse of a specified duration in
response to an input trigger. Figure 8 shows a schematic diagram of the
circuit.
Practical Exercise 9 7
FIGURE 7—Insert the IC
into the socket at U1
,
making sure that pin 1 of
the IC is closest to the
“U1” marking on the
board.
FIGURE 8—This schematic
diagram illustrates the
touch switch circuit you just
constructed on your circuit
board.Now, let’s test the operation of your touch switch circuit. The trigger for
the circuit will be provided by your body. Stray signals picked up by
your body will be sufficient to cause the monostable to produce an output pulse.
Step 25: Connect a 9 V battery to the battery holder and make sure
that the switch is in the ON position. (The ON position is
with the switch trigger toward the BAT+ marking on the circuit board.)
Step 26: Touch your finger to the probe tip that extends from hole E
on the circuit board. The LED should turn on for a short duration, then switch off. Each time you touch the probe tip, the
LED should light for the same duration, indicating the presence of the output pulse.
Step 27: Adjust RX
, the 100 k control mounted on the circuit board.
Observe how the position of the control affects the duration
of the output pulse.
When RX
is in its middle position, its resistance value will be approximately 50 k. You can use this value to calculate the output pulse
width by using the following formula:
pulse width = 1.1 ″ (RX
+ R2
)″ C2
Substitute the known values of RX
, R2
, and C2
into the formula and
solve.
pulse width = 1.1 ″ (50 k + 22 k)″ 4.7 F
pulse width = 1.1 ″ (50,000 + 22,000)″ 0.0000047F
pulse width = 1.1 ″ (72,000)  0.0000047
pulse width = 79,200 ″ 0.0000047
pulse width = 0.37224 seconds
The actual value that you measure may vary somewhat from the calculated value due to component tolerances. However, you should be able
to clearly demonstrate the action of the one-shot and verify the action of
the pulse-width-determining components.
When you’ve finished your experiments with the one-shot, turn off the
power switch and disconnect the 9 V battery. Keep the circuit on the
circuit board to use in the next activity.
8 Practical Exercise 9Activity 2
The purpose of this activity is to modify your touch switch circuit to
convert it to an audio oscillator. To complete this activity, you’ll need
the circuit board with the one-shot that you constructed in the previous
activity, a 0.01 F film capacitor, and a miniature piezoelectric
transducer.
Now, when you’re ready, work through the following steps to convert
your touch switch to an audio oscillator. Figure 9 shows the location of
the new components on the circuit board.
Step 1: Connect the free end of the wire connected to hole E to hole F
on the circuit board. Solder the wire to the foil, and clip off
any excess lead length.
Step 2: Use your desoldering tool to unsolder and remove C2
, the
4.7 F electrolytic. (This capacitor won’t be used again.)
Step 3: Unsolder and remove both ends of the jumper wire that’s
connected between holes A and D. (This jumper wire won’t
be used again.)
Step 4: Cut a 1
2
-inch length of hookup wire and strip all of the insulation from the wire. Connect this wire from hole A to hole B
on the circuit board, and solder both ends to the foil. Clip off
any excess lead length.
Practical Exercise 9 9
B A
R1
C3
BAT
BAT
C1
SPKR
SW 1
E
C
R3
J2
Q2
J1
C2
R2
F
MODEL
213
b
e
e
c
b c
U1
+

– +
– +
– +
+
RX/Q1
RED LEAD
FIGURE 9—This illustration
shows the location of the
0.01 F film capacitor and
the piezoelectric transducer
on the circuit board.Step 5: Mount a 0.01 F film capacitor at the C2
position on the circuit board. Clip off any excess lead lengths.
Step 6: Mount the piezoelectric transducer at the SPKR position on
the circuit board. Note that the transducer terminals are identified as positive (+) and negative (–). Make sure that the
positive (+) terminal on the transducer goes in the positive
(+) terminal on the circuit board.
Figure 10 shows the schematic of the circuit you just constructed on
your circuit board. This circuit is an audio oscillator that produces a
square wave at its output.
The positive and negative excursions of the square wave produced by
the circuit are separately determined by the combination of R1
, R2
and
C1
. In other words, the square wave isn’t necessarily symmetrical.
The positive-going portion of the square wave can be calculated with
the following formula:
high output (in seconds) = 0.693 ″ (RX
+ R2
)″ C1
The negative-going portion of the square wave can be calculated with
the following formula:
low output (in seconds) = 0.693 ″ R2
″ C1
One complete cycle of the square wave is equal to the high-output duration plus the low-output duration.
To convert the duration into frequency, you can use the following
formula:
f
T

1
10 Practical Exercise 9
FIGURE 10—This illustration is
a schematic diagram of the
audio oscillator circuit you
just constructed on your circuit board.In this equation, f stands for the frequency in cycles per second, and T
stands for the time of one complete cycle in seconds.
Now, connect the 9 V battery to the battery holder and turn on the
power to your oscillator circuit. Adjust the 100 k control over its
range and observe the effect that it has on the frequency. By adjusting
the 100 k control to its maximum (lowest output frequency) and to its
midpoint (50 k) , you can determine the frequency.
You can substitute the values from the high-output and low-output formulas for T to obtain the following formula:
f
R R C X

 
1 44
2
2 2
.
[ ( )] ″
Try substituting the value 100 k for RX
in this formula and solve for
the frequency.
f
R R C X

 
1 44
2
2 2
.
[ ( )] ″
f 

1 44
100 2 22 0 01
.
[ ( ] . k k F   ″ ″ 
f 

1 44
100 000 2 22 000 0 00000001
.
[ , ( , )] .   ″ ″ F
f 

1 44
100 00 44 000 0 00000001
.
[ , , ] .   ″ F
f 
1 44
144 000 0 00000001
.
, . ″ F
f  
1 44
0 00144
1 000
.
.
, Hz
Now, try substituting the value 50 k for RX
in this formula and solve
for the frequency.
f
R R C X


1 44
2
2 2
.
[ ( )] ″ ″
f 

1 44
50 2 22 0 01
.
[ ( )] . k k F   ″ ″ 
f 

1 44
50 000 2 22 000 0 00000001
.
[ , ( , )] .   ″ ″ F
f 

1 44
50 000 44 000 0 00000001
.
[ , , ] .   ″ F
f 
1 44
94 000 0 00000001
.
, . ″ F
Practical Exercise 9 11f  
1 44
0 00094
1 531
.
.
, Hz
Now, turn off your oscillator circuit and disconnect the 9 V battery. In
the next activity, you’ll make further modifications to this same circuit
and install the circuit board in its cabinet.
Activity 3
In this activity, you’ll convert your oscillator circuit into a continuity
checker. To complete this activity, you’ll need your circuit board with
the oscillator circuit already installed on it from the previous activity.
You’ll also need the components in the following list. At this time, locate the components in your parts pack and check them off on the list.
Now, when you’re ready, work through the following steps to convert
your audio oscillator circuit to a continuity checker. Figure 11 shows the
location of the new components on the circuit board.
Step 1: Unsolder and remove the jumper wire between point “c”
and point “C” on the circuit board. (This was illustrated in
Figure 9.)
Step 2: Unsolder and remove the 100 k potentiometer. (This component won’t be used again.) Mount R3, the 100 k resistor,
to the circuit board at the R3 location and solder in place.
Step 3: Mount one of the 2SA1015Y transistors at the Q1
position on
the circuit board. Insert the transistor so that the flat side
aligns with the markings on the circuit board. Push the transistor into the board so that it sits approximately 3
16
inch
above the surface of the board. Solder the leads to the foil,
and clip off any excess lead lengths.
Step 4: In the same way, mount the second transistor 2SA1015Y at
the Q2
position on the circuit board. Again, make sure that
the flat side on the transistor aligns with the marking on the
board. Position the transistor 3
16
inch above the surface of the
board and solder the leads to the foil. Clip off any excess lead
lengths.
12 Practical Exercise 9
✔ Description Quantity
R3/100 k resistor (brown-black-yellow) 1
2SA1015Y transistor 2
Instrument case 1
Red banana jack with hardware 1
Black banana jack with hardware 1
Probe set (red and black) 1
3 8 self-tapping screws 2
Cabinet label 1Now, refer to Figure 12 as you work through the following steps.
Step 5: Locate the red banana jack and remove the hardware from
the jack.
Step 6: Insert the inner insulator and jack into the left hole of the
case.
Practical Exercise 9 13
B A
R1
C3
BAT
BAT
C1
SPKR
SW 1
E
C
R3
J2
Q2
J1
C2
R2
F
MODEL
213
e
e
c
c
U1
+

– +
– +
– +
+
RX/Q1
RED LEAD
FIGURE 11—This illustration
shows the location of two
2SA1015Y transistors on
your circuit board.
FLAT END
OUTER
INSULATOR
WASHER
NUT
RED
INNER
INSULATOR
BLACK
METAL
JACK
FIGURE 12—This figure illustrates how to install the red
and black banana jacks.Step 7: While you hold the jack with your finger, install the outer
insulator. Make sure that the flat end is closes to the case.
Install one flat washer and one nut onto the jack as shown in
Figure 12. Tighten the nut using only your fingers (it will be
fully tightened later).
Step 8: In the same way, mount the black banana jack. Install the flat
washer and nut, and tighten the nut using only your fingers.
Step 9: Make sure that the two jacks are as far apart as possible, and
then securely tighten both nuts.
Now, refer to Figure 13 as you work through the following steps.
Step 10: Place one solder tab on the red jack. Secure the tab in place
with one of the nuts that was removed earlier. Tighten the
nut while keeping the solder tab pointed up as shown in
Figure 13.
Step 11: Place the other solder tab on the black jack. Secure the tab in
place with the remaining nut while keeping it pointed up as
shown in Figure 13.
Step 12: Bend both solder tabs outward so that they’re parallel with
the front of the cabinet as shown.
Refer to Figure 14 as you work through the following steps.
14 Practical Exercise 9
FIGURE 13—This figure
illustrates how to secure
the solder tabs to the
banana jacks.Step 13: Insert the circuit board into the cabinet, making sure that the
power switch and the LED are in the holes provided. Secure
the board in place by using two 3 ″ 8 mm self-tapping screws.
Step 14: Cut a 1-inch length of hookup wire and remove all of the insulation from the wire. Then, cut the bare wire in half.
Step 15: Make a small hook in one end of each piece of wire. Then,
insert the straight end of one hooked wire through the red
solder tab and into the J
1
RED hole in the circuit board
(Figure 15). Solder the wire to the solder tab and to the hole
in the circuit board.
Practical Exercise 9 15
FIGURE 14—This illustration shows you how to install the circuit board in
the cabinet.
J1
J2
FIGURE 15—Make a small
hook in the end of your
piece of wire, then insert
the straight end of one
hooked wire through the
red solder tab and into
the J
1
RED hole in the circuit board.Step 16: In the same way, make a small hook in one end of the second
piece of wire. Then, insert the straight end of the hooked wire
through the black solder tab and into the hole marked J
2
BLACK in the circuit board. Solder the wire to the solder tab
and to the hole in the circuit board.
Set the completed circuit board and cabinet aside in a safe place while
you assemble the test leads. Refer to Figure 16 as you work through the
following steps.
16 Practical Exercise 9
PROBE
TIPS
BANANA
PLUG TIPS
SHORT PLUG
HOUSINGS
LONG PROBE
HANDLES
RED
BLACK
RED
(A)
WIRE
SOLDER
PROBE
TIP
SOLDERING
IRON
VISE
(B)
FIGURE 16—This figure illustrates the construction of
the test leads.Step 17: Remove the test lead kit from its plastic bag.
Step 18: Cut the tinned conductors on the ends of both wires to 1
8
inch.
Step 19: Hold one of the probe tips with pliers or in a vise as shown in
Figure 16B. Heat the top of the probe tip with your soldering
iron, and fill the recess with solder. As you continue to heat
the solder in the recess, insert the tip of the red wire into the
molten solder. Remove the iron and hold the wire steady until the solder solidifies. If you move the wire before the solder
has solidified, it will take on the dull, glazed appearance of a
cold solder joint. If this happens, simply reheat the solder and
allow it to solidify once more while holding the lead steady.
Step 20: Repeat the previous step with the other probe tip and the
black lead.
Step 21: Insert the free end of the red wire into the threaded end of
the long red probe handle. Pull the wire all the way through
the handle, screw the probe tip into the handle, and tighten.
Step 22: Insert the free end of the black wire into the threaded end
of the long black probe handle. Pull the wire all the way
through the handle, screw the probe tip into the handle, and
tighten.
Step 23: Insert the free end of the red wire into the nonthreaded end
of the short red plug housing. Slide the housing all the way
into the probe handle.
Step 24: Insert the free end of the black wire into the nonthreaded end
of the short black plug housing. Slide the housing all the way
into the probe handle so it doesn’t get in the way of
soldering.
Step 25: Place one of the banana plug tips vertically in a vise, or hold
it with pliers with the threaded section on top. Be careful not
to crush the plug while you’re holding it.
Step 26: Heat the top of the metal plug with your soldering iron, and
fill the recess with solder. While keeping the solder in the recess hot, insert the free end of the red wire vertically into the
molten solder. Remove the heat and hold the wire still until
the solder solidifies.
Step 27: Repeat the previous two steps with the other metal banana
plug and the black wire.
Practical Exercise 9 17Step 28: Slide the red plastic housing up to the banana plug, screw the
plug into the housing, and tighten. Repeat this procedure for
the black housing and plug.
Step 29: Connect a 9 V battery to the battery holder.
Step 30: Plug the red test lead into the red banana jack and the black
lead into the black banana jack.
Step 31: Turn on the power switch and touch the test leads together.
You should hear a steady tone. When you separate the test
leads, the tone should stop.
If you don’t hear the tone when the test leads are touched together, turn
off the power switch and carefully inspect the connections on your circuit board. Look for unsoldered connections, solder bridges between
adjacent holes on the board, or components that were installed incorrectly. You may have to remove the board from the cabinet to ensure
that the transistors were correctly installed.
Now, refer to Figure 17 as you work through the following steps.
Step 32: Install the battery in the case as shown in Figure 17.
Step 33: Mount the case cover, making sure that you don’t pinch any
wires.
Step 34: Insert and tighten four 3 ″ 8 mm self-tapping screws to hold
the cover in place and install the label. Your continuity tester
is now completely assembled.
The continuity tester allows you to quickly check a circuit to see if it’s
open, shorted, or has some resistance across it. Touch the test leads
together and listen to the tone. This tone indicates zero resistance or a
short circuit. When you’re testing fuses or closed switches, this is the
tone you should hear.
Now, moisten your fingers and hold each of the test leads in one hand.
Again, you’ll hear sound from the transducer (it could be a lowfrequency clicking sound). This sound indicates a relatively high
resistance between the probes.
As your knowledge of electronics and circuit operation increases,
you’ll be able to perform a wide range of troubleshooting tests with
your continuity checker. A short circuit is indicated by a relatively
high-frequency tone. Increasing values of resistance are indicated by
progressively lower-frequency tones, all the way down to a series of
low-frequency clicks.
18 Practical Exercise 9WARNING: Do not connect your continuity checker to any circuit that
has power applied to it. This could result in damage to your
instrument, as well as to the circuit under test.
Conclusion
We hope you enjoyed these suggested exercises! Now, when you’re
ready, proceed to the graded portion of the practical exercise that
follows. This part of the exercise is completed in the same way as the
other examinations for your program. Remember, you can refer back to
your program materials at any time if you feel that you need to review
any material. When you’re finished with the examination, send your
answers in to the school for grading. Good luck!
Practical Exercise 9 19
PCB
(A)
(B)
FIGURE 17—This figure shows the installation of the cover and the label.NOTES
20 Practical Exercise 9Practical Exercise 9
When you feel confident that you have mastered the material in this practical exercise, complete
the following examination. Then submit only your answers to the school for grading, using one of
the examination answer options described in your “Test Materials” envelope. Send your answers
for this examination as soon as you complete it. Do not wait until another examination is ready.
Questions 1–20: Select the one best answer to each question.
1. A modulation technique that uses two tones that are separated in frequency is called
A. FSK. C. CTSS.
B. LSB. D. SSB.
2. In order to recover audio from a received single sideband signal, the receiver must
A. have an extremely narrow bandwidth.
B. reinsert the missing carrier.
C. contain a balanced modulator.
D. have several stages of frequency multiplication.
3. Which of the following represents an invalid DTMF tone pair?
A. 941 and 1209 C. 1336 and 852
B. 1336 and 770 D. 1633 and 1477
Examination 21
EXAMINATION NUMBER:
00290901
Whichever method you use in submitting your exam
answers to the school, you must use the number above.
For the quickest test results, go to
http://www.takeexamsonline.com4. Look at the schematic diagram shown in Figure A-1. This schematic diagram represents a
A. Wein bridge oscillator. C. twin-T oscillator.
B. phase-shift oscillator. D. relaxation oscillator.
5. In the circuit illustrated in Figure A-1, which of the following are frequency-determining components?
A. R1
and R2
C. C1
and R3
B. R2
and R5
D. R1
and C4
6. Look at the schematic diagram shown in Figure A-2. In this circuit, the lamp will light only when
A. S2
is closed and S1
is in position B.
B. S2
is closed and S1
is in position A or position B.
C. S2
is closed and S1
is in position A.
D. S2
is closed and S1
is in position A, position B, or position C.
7. Which of the following statements about series regulators is correct?
A. Series regulators are inherently less efficient than shunt regulators because the current through
the shunt regulator flows through the load.
B. Series regulators are inherently more efficient than shunt regulators because the current through
the shunt regulator flows through the load.
C. Series regulators are inherently less efficient than shunt regulators because the current through
the shunt regulator doesn’t flow through the load.
D. Series regulators are inherently more efficient than shunt regulators because the current through
the shunt regulator doesn’t flow through the load.
22 Examination
C1 C2 C3 R2
R1
R3 R4 R5
C4
+

FIGURE A-1—Use this illustration to answer Questions
4 and 5.
LAMP
S2
S1
POSITION A
POSITION C
POSITION B
FIGURE A-2—Use this illustration to
answer Question 6.8. Look at the circuit diagram shown in Figure A-3. An electronics technician measures a voltage of 25.7
V at the collector of Q 2
. Which of the following statements about this circuit is correct?
A. The circuit is operating normally.
B. Resistor R1
is open in the circuit.
C. An emitter-to-base short is present in Q1
.
D. Resistor R3
has increased in value.
9. In the circuit shown in Figure A-3, an electronics technician measures the output voltage of the
regulator circuit at 30 V. Which of the following statements about this circuit is correct?
A. A collector-to-emitter short is present in Q1
.
B. Resistor R2
is shorted.
C. Resistor R4
is shorted.
D. Resistor R1
is open.
10. When a load is applied to the power supply in the circuit shown in Figure A-3, the output voltage
tends to decrease. Which of the following actions in the circuit counteracts this tendency?
A. The conduction of Q2
decreases.
B. The conduction of Q1
decreases.
C. The voltage at the emitter of Q2
increases.
D. The voltage at the junction of R3
and R4
increases.
11. Look at the schematic diagram shown in Figure A-4. This circuit diagram represents a(n)
A. Wein bridge oscillator. C. full-wave rectifier.
B. frequency synthesizer. D. audio amplifier.
12. In the circuit illustrated in Figure A-4, which of the following factors determines the accuracy of the
output frequency?
A. The stability of the VCO C. The stability of the phase detector
B. The accuracy of the divider D. The accuracy of the reference signal
Examination 23
20 V
DZ
R4
R5
R3
POWER
SUPPLY
R2
R1 20.7 V
Q2
Q1
+ 30 V
25 V
FIGURE A-3—Use this illustration to answer Questions 8,
9, and 10.13. For the circuit shown in Figure A-4, what countdown is necessary from the divider circuit to produce
an output frequency of 10 MHz? (Assume a reference frequency of 100 kHz.)
A. 10 C. 1,000
B. 100 D. 10,000
14. At which of the following points in the circuit shown in Figure A-4 would it be normal to measure a
varying DC voltage?
A. Point 1 C. Point 3
B. Point 2 D. Point 4
15. Which of the following does a relaxation oscillator depend on for proper operation?
A. Positive feedback C. Negative resistance
B. Negative feedback D. Frequency synthesis
16. Look at the schematic diagram and the four waveforms that are shown in Figure A-5. Which of the
following statements about this circuit is correct?
A. To obtain waveform 3 at the output of this circuit, both switch S1
and switch S3
would have to be
closed.
B. To obtain waveform 3 at the output of this circuit, either switch S1
or switch S3
must be closed.
C. To obtain waveform 3 at the output of this circuit, only switch S2
must be closed.
D. No combination of closed switches will produce waveform 3 at the output of this circuit.
17. Again, look at the circuit diagram and the four waveforms that are shown in Figure A-5. Which of the
following waveforms will be produced when only S1
is closed?
A. Waveform 1 C. Waveform 3
B. Waveform 2 D. Waveform 4
24 Examination
PHASE
DETECTOR
DIVIDE-BY
N
VOLTAGECONTROLLED
OSCILLATOR
REFERENCE
SIGNAL
POINT 2
POINT 3
POINT 1
POINT 4
OUTPUT
FIGURE A-4—Use this illustration to answer Questions
11, 12, 13, and 14.18. In order for a circuit to oscillate, it’s absolutely essential that the circuit have
A. degenerative feedback. C. negative resistance.
B. regenerative feedback. D. a gain of less than unity.
19. Look at the block diagram shown in Figure A-6. Which of the following multiplication factors must take
place in the two unmarked stages to obtain the 60 kHz output?
A. ″ 6 and ″ 6 C. ″ 5 and ″ 5
B. ″ 6 and ″ 2 D. ″ 3 and ″ 2
Examination 25
FIGURE A-5—Use this illustration to answer Questions 16
and 17.
? x 2
5 kHz
OSCILLATOR
? 60 kHz
FIGURE A-6—Use this
illustration to answer
Question 19.20. Look at the circuit diagram and the four waveforms that are shown in Figure A-7. Which of the four ripple waveforms shown would result if D2
were to open?
A. Waveform 1 C. Waveform 3
B. Waveform 2 D. Waveform 4

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