Multivibrators and 555 Timer problems
- 1. 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
Correct Answer: It has an active-HIGH reset, which terminates all timing functions.
- 2. With most monostable multivibrators, what is the Q output when no input trigger has occurred?
Options- A. LOW
- B. +5 V
- C. SET
- D. HIGH Discuss
Correct Answer: LOW
- 3. The output of the astable circuit ________.
Options- A. constantly switches between two states
- B. is LOW until a trigger is received
- C. is HIGH until a trigger is received
- D. floats until triggered Discuss
Correct Answer: constantly switches between two states
- 4. When a capacitor charges:
Options- A. the voltage across the plates rises exponentially
- B. the circuit current falls exponentially
- C. the capacitor charges to the source voltage in 5×RC seconds
- D. all of the above Discuss
Correct Answer: all of the above
- 5. The pulse width out of a one-shot multivibrator increases when the:
Options- A. supply voltage increases
- B. timing resistor decreases
- C. UTP decreases
- D. timing capacitance increases Discuss
Correct Answer: supply voltage increases
- 6. What is another name for a bistable multivibrator?
Options- A. an on-off switch
- B. an oscillator
- C. a flip-flop Discuss
Correct Answer: a flip-flop
- 7. A 0.3-µF capacitor has an initial charge of 2.7 V. If it is discharged through a 10-kΩ resistor for 6.5 ms, how much voltage will be left across the capacitor?
Options- A. 0.0 V
- B. 0.309 V
- C. 2.7 V
- D. 2.295 V Discuss
Correct Answer: 0.309 V
- 8. The bistable multivibrator is an R-C flip-flop.
Options- A. True
- B. False Discuss
Correct Answer: False
- 9. A single Schmitt trigger inverter is all that is needed to build a simple astable multivibrator.
Options- A. True
- B. False Discuss
Correct Answer: False
- 10. In the 74121, which is nonretriggerable, any triggers that come in before the end of the timing cycle are ignored.
Options- A. True
- B. False Discuss
Correct Answer: True
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