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# 2708A 2708b pennfoster pulse circuits exam

### Customer Question

2708A 2708b
pennfoster pulse circuits exam
Submitted: 13 days ago.
Category: Homework
Customer: replied 13 days ago.
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-u-
INPUT
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 peri
Expert:  Wiz of All replied 12 days ago.

Hi

Please tell me asap so that I get started with the solution. :)

Thanks

Customer: replied 12 days ago.
ASAP
Customer: replied 12 days ago.
How long do you think it may take
Customer: replied 12 days ago.
how soon will I have these answers
Expert:  Wiz of All replied 11 days ago.

Hi

Some questions you sent are incomplete. Is it okay if I send you the solution for the remaining questions?

I'll do my best to send it before the end of the day.

Thanks

Customer: replied 11 days ago.
that will be fine its to just check my answers. Thank you
Expert:  Wiz of All replied 11 days ago.

Hi

Please know that I have tried answering them to the best of my knowledge and just like you said you need to only check them against your own solution then I think its alright.

https://www.mediafire.com/?222x1yu4tdrvoaw

Customer: replied 11 days ago.
Not good that's for sure did it my way got 75 your was 64
Customer: replied 11 days ago.
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"' uz
.<..(
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
Customer: replied 11 days ago.
Expert:  Wiz of All replied 11 days ago.

Sorry I won't be able to help you with the last set :(

I have tried but i'm afraid i might be wrong and I don't want to affect your result

Customer: replied 11 days ago.
Expert:  Wiz of All replied 11 days ago.

I would give it a try if I had some time to go through it. Is it okay if i solve it by tomorrow?

Customer: replied 11 days ago.
that's fine even by Monday is good please just let me known
Expert:  Wiz of All replied 11 days ago.

Okay I will.

I will try to solve it to the best of my knowledge.

Expert:  Wiz of All replied 9 days ago.

Hi

This is the best I could do for you. Know that I'm not sure of the answers though but I did as you asked me to-I gave it a try :)

4 a
6 b
10 b
11 a
13 c
16 c or d
17 d
18 a
19 b
20 b
21 b

Expert:  Wiz of All replied 8 days ago.