Q.1

What is the difference between an astable multivibrator and a monostable multivibrator?

  • The astable is free running.
  • The astable needs to be clocked.
  • The monostable is free running.
  • none of the above
Q.2

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
Q.3

Is there any limit to the number of times that a 74123 can be retriggered?

  • yes
  • no
Q.4

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
Q.5

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
Q.6

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
Q.7

The pulse width out of a one-shot multivibrator increases when the:

  • supply voltage increases
  • timing resistor decreases
  • UTP decreases
  • timing capacitance increases
Q.8

The output of the astable circuit ________.

  • constantly switches between two states
  • is LOW until a trigger is received
  • is HIGH until a trigger is received
  • floats until triggered
Q.9

The pulse width out of a one-shot multivibrator increases when the:

  • supply voltage increases
  • timing resistor decreases
  • UTP decreases
  • timing capacitance increases
Q.10

The pulse width out of a one-shot multivibrator increases when the:

  • supply voltage increases
  • timing resistor decreases
  • UTP decreases
  • timing capacitance increases
Q.11

If a diode is connected across resistor RB (positive end up) in the given figure, what is the new duty cycle of the output waveform?

  • 56%
  • 44%
  • 21.6%
  • 17.4%
Q.12

If a diode is connected across resistor RB (positive end up) in the given figure, what is the new duty cycle of the output waveform?

  • 56%
  • 44%
  • 21.6%
  • 17.4%
Q.13

Pulse stretching, time-delay, and pulse generation are all easily accomplished with which type of multivibrator circuit?

  • astable
  • monostable
  • multistable
  • bistable
Q.14

What is the difference between a retriggerable one shot and a nonretriggerable one shot?

  • The nonretriggerable can only be triggered once.
  • The retriggerable can be triggered many times.
  • The output pulse can be stretched with a nonretriggerable.
  • The output pulse can be stretched with a retriggerable.
Q.15

What controls the output pulse width of a one shot?

  • the clock frequency
  • the width of the clock pulse
  • an RL time constant
  • an RC time constant
Q.16

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.

  • a comparator
  • a voltage amplifier
  • two comparators
  • a peak detector
Q.17

Triggering a retriggerable one shot during pulse generation will:

  • time out the original pulse
  • extend the pulse to this trigger width
  • have no effect
  • double the original pulse width
Q.18

What controls the output pulse width of a one shot?

  • the clock frequency
  • the width of the clock pulse
  • an RL time constant
  • an RC time constant
Q.19

What is the function of the comparators in the 555 timer circuit?

  • to compare the output voltages to the internal voltage divider
  • to compare the input voltages to the internal voltage divider
  • to compare the output voltages to the external voltage divider
  • to compare the input voltages to the external voltage divider
Q.20

The bistable multivibrator is an R-C flip-flop.

  • True
  • False
0 h : 0 m : 1 s