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Home ‣ Digital Electronics ‣ Multivibrators and 555 Timer Comments
- Question
Design a circuit using a 74121 to convert a 33-kHz, 30% duty cycle waveform to a 33-kHz, 60% duty cycle waveform.
Options- A. Rint = 2 kΩ, Cext = 0.012 nF
- B. Rint = 2 kΩ, Cext = 0.012 µF
- C. Rint = 4 kΩ, Cext = 0.012 nF
- D. Rint = 4 kΩ, Cext = 0.012 µF
- Correct Answer
- Rint = 2 kΩ, Cext = 0.012 µF
- 1. What is the duty cycle of the waveform at the output of the circuit given below?
Options- A. 78%
- B. 56%
- C. 50%
- D. 44% Discuss
- 2. The internal circuitry of the 555 timer consists of ________, an R-S flip-flop, a transistor switch, an output buffer amplifier, and a voltage divider.
Options- A. a comparator
- B. a voltage amplifier
- C. two comparators
- D. a peak detector Discuss
- 3. What controls the output pulse width of a one shot?
Options- A. the clock frequency
- B. the width of the clock pulse
- C. an RL time constant
- D. an RC time constant Discuss
- 4. What does the discharge transistor do in the 555 timer circuit?
Options- A. charge the external capacitor to stop the timing
- B. charge the external capacitor to start the timing over again
- C. discharge the external capacitor to stop the timing
- D. discharge the external capacitor to start the timing over again Discuss
- 5. Does the 74123 one shot have an internal timing resistor?
Options- A. yes
- B. no Discuss
- 6. What is the pulse width of the output of a 74123 if an external 4.7-kΩ resistor and a 0.022-µF capacitor are used?
Options- A. 290 ms
- B. 29 ms
- C. 33.3 µs
- D. 290 µs Discuss
- 7. A monostable 555 timer has the following number of stable states:
Options- A. 0
- B. 1
- C. 2
- D. 3 Discuss
- 8. Pulse stretching, time-delay, and pulse generation are all easily accomplished with which type of multivibrator circuit?
Options- A. astable
- B. monostable
- C. multistable
- D. bistable Discuss
- 9. What is the difference between a retriggerable one shot and a nonretriggerable one shot?
Options- A. The nonretriggerable can only be triggered once.
- B. The retriggerable can be triggered many times.
- C. The output pulse can be stretched with a nonretriggerable.
- D. The output pulse can be stretched with a retriggerable. Discuss
- 10. Which of the following is NOT a characteristic of a retriggerable monostable multivibrator?
Options- A. It is a dual multivibrator.
- B. It has an active-HIGH reset, which terminates all timing functions.
- C. It has no internal timing resistor.
- D. none of the above Discuss
Multivibrators and 555 Timer problems
Search Results
Correct Answer: 56%
Correct Answer: two comparators
Correct Answer: an RC time constant
Correct Answer: discharge the external capacitor to start the timing over again
Correct Answer: no
Correct Answer: 33.3 µs
Correct Answer: 1
Correct Answer: monostable
Correct Answer: The output pulse can be stretched with a retriggerable.
Correct Answer: It has an active-HIGH reset, which terminates all timing functions.
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