Flip-Flops problems
- 1. A 555 operating as a monostable multivibrator has a C1 = 100 µF. Determine R1 for a pulse width of 500 ms.
Options- A. 45 Ω
- B. 455Ω
- C. 4.5 kΩ
- D. 455 kΩ Discuss
Correct Answer: 4.5 kΩ
- 2. As a general rule for stable flip-flop triggering, the clock pulse rise and fall times must be:
Options- A. very long.
- B. very short.
- C. at a maximum value to enable the input control signals to stabilize.
- D. of no consequence as long as the levels are within the determinate range of value. Discuss
Correct Answer: very short.
- 3. Propagation delay time, tPLH, is measured from the ________.
Options- A. triggering edge of the clock pulse to the LOW-to-HIGH transition of the output
- B. triggering edge of the clock pulse to the HIGH-to-LOW transition of the output
- C. preset input to the LOW-to-HIGH transition of the output
- D. clear input to the HIGH-to-LOW transition of the output Discuss
Correct Answer: triggering edge of the clock pulse to the LOW-to-HIGH transition of the output
- 4. The output pulse width of a 555 monostable circuit with R1 = 4.7 kΩ and C1 = 47 µF is ________.
Options- A. 24 s
- B. 24 ms
- C. 243 ms
- D. 243 µs Discuss
Correct Answer: 243 ms
- 5. What does the triangle on the clock input of a J-K flip-flop mean?
Options- A. level enabled
- B. edge-triggered Discuss
Correct Answer: edge-triggered
- 6. What is another name for a one-shot?
Options- A. Monostable
- B. Multivibrator
- C. Bistable
- D. Astable Discuss
Correct Answer: Monostable
- 7. An invalid condition in the operation of an active-HIGH input S-R latch occurs when ________.
Options- A. HIGHs are applied simultaneously to both inputs S and R
- B. LOWs are applied simultaneously to both inputs S and R
- C. a LOW is applied to the S input while a HIGH is applied to the R input
- D. a HIGH is applied to the S input while a LOW is applied to the R input Discuss
Correct Answer: HIGHs are applied simultaneously to both inputs S and R
- 8. The timing network that sets the output frequency of a 555 astable circuit contains ________.
Options- A. three external resistors are used
- B. two external resistors and an external capacitor are used
- C. an external resistor and two external capacitors are used
- D. no external resistor or capacitor is required Discuss
Correct Answer: two external resistors and an external capacitor are used
- 9. If an active-HIGH S-R latch has a 0 on the S input and a 1 on the R input and then the R input goes to 0, the latch will be ________.
Options- A. SET
- B. RESET
- C. clear
- D. invalid Discuss
Correct Answer: RESET
- 10. What is the difference between the enable input of the 7475 and the clock input of the 7474?
Options- A. The 7475 is edge-triggered.
- B. The 7474 is edge-triggered. Discuss
Correct Answer: The 7474 is edge-triggered.
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