Multivibrators and 555 Timer Questions and Answers

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Q11
What is the difference between an astable multivibrator and a monostable multivibrator?
  • A The astable is free running.
  • B The astable needs to be clocked.
  • C The monostable is free running.
  • D none of the above
Answer: Option A
Q12
Is there any limit to the number of times that a 74123 can be retriggered?
  • A TRUE
  • B FALSE
Answer: Option B
Q13
The output of the astable circuit ________.
  • 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
Answer: Option A
Q14
What controls the output pulse width of a one shot?
  • A the clock frequency
  • B the width of the clock pulse
  • C an RL time constant
  • D an RC time constant
Answer: Option D
Q15
Does the 74123 one shot have an internal timing resistor?
  • A TRUE
  • B FALSE
Answer: Option B
Q16
In a typical IC monostable multivibrator circuit, at the falling edge of the trigger input, the output switches HIGH for a period of time determined by the ________.
  • A value of the RC timing components
  • B amplitude of the input trigger
  • C frequency of the input trigger
  • D magnitude of the dc supply voltage
Answer: Option A
Q17
monostable 555 timer has the following number of stable states:
  • A 0
  • B 1
  • C 2
  • D 3
Answer: Option B
Q18
Triggering a retriggerable one shot during pulse generation will:
  • A time out the original pulse
  • B extend the pulse to this trigger width
  • C have no effect
  • D double the original pulse width
Answer: Option B
Q19
Triggering a retriggerable one shot during pulse generation will:
  • A time out the original pulse
  • B extend the pulse to this trigger width
  • C have no effect
  • D double the original pulse width
Answer: Option B
Q20
The monostable multivibrator circuit is not an oscillator because ________.
  • A its output switches between two states
  • B it requires a trigger to obtain an output signal
  • C it requires a sine wave input signal
  • D the circuit does not require a dc power supply
Answer: Option B
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