Civil Engineering Mechanical Engineering Chemical Engineering Networking Database Questions Computer Science Basic Electronics Digital Electronics Electronic Devices Circuit Simulation Electrical Enigneering Engineering Mechanics Technical Drawing

# Digital Electronics - Multivibrators and 555 Timer

### Exercise

"No one is as deaf as the man who will not listen."
- (Proverb)
1.

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

2.

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

3.

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

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?

 A. 0.44 ms B. 0.501 ms C. 0.66 ms D. 0.70 ms

5.

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