Multivibrators and 555 Timer Questions and Answers
Multivibrators and 555 Timer questions with answers help electronics aspirants strengthen their understanding of pulse generation and timing circuits. The 555 timer IC is widely used in monostable, astable, and bistable multivibrator configurations, making it a frequent topic in exams like DRDO, ISRO, and GATE. Mastering these circuits enhances conceptual clarity in waveform generation, duty cycle control, and timing applications. This section provides well-explained aptitude questions and answers that simulate actual electronics exams, helping students test their theoretical knowledge through practical problem-solving. Whether preparing for technical interviews or competitive electronics tests, this topic gives you an edge through step-by-step solutions and real-world applications of timing circuits.
Multivibrators and 555 Timer
11. 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
12. Is there any limit to the number of times that a 74123 can be retriggered?
- TRUE
- FALSE
13. 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
14. 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
16. 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 ________.
- value of the RC timing components
- amplitude of the input trigger
- frequency of the input trigger
- magnitude of the dc supply voltage
18. 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
19. 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
20. The monostable multivibrator circuit is not an oscillator because ________.
- its output switches between two states
- it requires a trigger to obtain an output signal
- it requires a sine wave input signal
- the circuit does not require a dc power supply