Multivibrators and 555 Timer Questions and Answers

Practice Mode
Showing 10 of 45 questions
Q1
What is the function of the comparators in the 555 timer circuit?
  • A to compare the output voltages to the internal voltage divider
  • B to compare the input voltages to the internal voltage divider
  • C to compare the output voltages to the external voltage divider
  • D to compare the input voltages to the external voltage divider
Answer: Option B
Q2
When a capacitor charges:
  • 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
Answer: Option D
Q3
The ________ is defined as the time the output is active divided by the total period of the output signal.
  • A on time
  • B off time
  • C duty cycle
  • D active ratio
Answer: Option C
Q4
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?
  • A 0.44 ms
  • B 0.501 ms
  • C 0.66 ms
  • D 0.70 ms
Answer: Option B
Q5
What does the discharge transistor do in the 555 timer circuit?
  • 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
Answer: Option D
Q6
Pulse stretching, time-delay, and pulse generation are all easily accomplished with which type of multivibrator circuit?
  • A astable
  • B monostable
  • C multistable
  • D bistable
Answer: Option B
Q7
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 a comparator
  • B a voltage amplifier
  • C two comparators
  • D a peak detector
Answer: Option C
Q8
With most monostable multivibrators, what is the Q output when no input trigger has occurred?
  • A LOW
  • B +5 V
  • C SET
  • D HIGH
Answer: Option A
Q9
An astable multivibrator requires:
  • A balanced time constants
  • B a pair of matched transistors
  • C no input signal
  • D dual J-K flip-flops
Answer: Option C
Q10
A crystal demonstrates the ________ effect when a mechanical force across the crystal causes a small voltage to be generated.
  • A photoelectric
  • B Co-pitts
  • C piezoelectric
  • D flywheel
Answer: Option C
Electronics
Back to Electronics
Questions and Answers for Competitive Exams Various Entrance Test