Digital Electronics- Multivibrators and 555 Timer
Digital Electronics- Multivibrators and 555 Timer
1. 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
2. When a capacitor charges:
- the voltage across the plates rises exponentially
- the circuit current falls exponentially
- the capacitor charges to the source voltage in 5×RC seconds
- all of the above
3. The ________ is defined as the time the output is active divided by the total period of the output signal.
- on time
- off time
- duty cycle
- active ratio
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?
- 0.44 ms
- 0.501 ms
- 0.66 ms
- 0.70 ms
5. What does the discharge transistor do in the 555 timer circuit?
- charge the external capacitor to stop the timing
- charge the external capacitor to start the timing over again
- discharge the external capacitor to stop the timing
- discharge the external capacitor to start the timing over again
6. Pulse stretching, time-delay, and pulse generation are all easily accomplished with which type of multivibrator circuit?
- astable
- monostable
- multistable
- bistable
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.
- a comparator
- a voltage amplifier
- two comparators
- a peak detector
8. With most monostable multivibrators, what is the Q output when no input trigger has occurred?
- LOW
- +5 V
- SET
- HIGH
9. An astable multivibrator requires:
- balanced time constants
- a pair of matched transistors
- no input signal
- dual J-K flip-flops
10. A crystal demonstrates the ________ effect when a mechanical force across the crystal causes a small voltage to be generated.
- photoelectric
- Co-pitts
- piezoelectric
- flywheel