Digital Electronics- Multivibrators and 555 Timer
Digital Electronics- Multivibrators and 555 Timer
21. A retriggerable one shot has a pulse of 10 ms. 3 ms after being triggered, another trigger pulse is applied. The resulting output pulse will be ________ ms.
- 3
- 7
- 10
- 13
22. What is another name for a bistable multivibrator?
- an on-off switch
- an oscillator
- a flip-flop
24. Which mode of operation is being used when a 555 timer chip has two external resistors and an external capacitor?
- monostable
- pulse stretching
- Schmitt triggering
- astable
25. Which of the following is NOT a characteristic of a retriggerable monostable multivibrator?
- It is a dual multivibrator.
- It has an active-HIGH reset, which terminates all timing functions.
- It has no internal timing resistor.
- none of the above
26. The pulse width out of a one-shot multivibrator increases when the:
- supply voltage increases
- timing resistor decreases
- UTP decreases
- timing capacitance increases
27. If the resistor in the Schmitt trigger astable multivibrator is a variable resistor, what part of the output voltage waveform will change when the resistance is changed?
- the shape of the waveform
- the amplitude of the waveform
- the period of the waveform
- none of the above
28. If Vcc of a 555 timer circuit is set to +10 V what is the level of output voltage from the circuit?
- VOH = 10 V, VOL = 0 V
- VOH = 10 V, VOL = 0.1 V
- VOH = 8.5 V, VOL = 0 V
- VOH = 8.5 V, VOL = 0.1 V
29. When extremely critical timing is required, a quartz crystal can be used.
- TRUE
- FALSE
30. In the 74121, which is nonretriggerable, any triggers that come in before the end of the timing cycle are ignored.
- TRUE
- FALSE