Multivibrators and 555 Timer MCQs

Question 1

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

Accepted Answer

to compare the input voltages to the internal voltage divider

Answer

to compare the output voltages to the internal voltage divider

Answer

to compare the output voltages to the external voltage divider

Answer

to compare the input voltages to the external voltage divider

Question 2

When a capacitor charges:

Accepted Answer

all of the above

Answer

the voltage across the plates rises exponentially

Answer

the circuit current falls exponentially

Answer

the capacitor charges to the source voltage in 5×RC seconds

Question 3

The ________ is defined as the time the output is active divided by the total period of the output signal.

Accepted Answer

duty cycle

Answer

on time

Answer

off time

Answer

active ratio

Question 4

A 22-k resistor and a 0.02-F capacitor are connected in series to a 5-V source. How long will it take the capacitor to charge to 3.4 V?

Accepted Answer

0.501 ms

Answer

0.44 ms

Answer

0.66 ms

Answer

0.70 ms

Question 5

What does the discharge transistor do in the 555 timer circuit?

Accepted Answer

discharge the external capacitor to start the timing over again

Answer

charge the external capacitor to stop the timing

Answer

charge the external capacitor to start the timing over again

Answer

discharge the external capacitor to stop the timing

Question 6

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

Accepted Answer

monostable

Answer

astable

Answer

multistable

Answer

bistable

Question 7

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.

Accepted Answer

two comparators

Answer

a comparator

Answer

a voltage amplifier

Answer

a peak detector

Question 8

With most monostable multivibrators, what is the Q output when no input trigger has occurred?

Accepted Answer

LOW

Answer

+5 V

Answer

SET

Answer

HIGH

Question 9

An astable multivibrator requires:

Accepted Answer

no input signal

Answer

balanced time constants

Answer

a pair of matched transistors

Answer

dual J-K flip-flops