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
31. The 74S124 TTL chip is a voltage-controlled oscillator that will generate a specific frequency at Vout.
- TRUE
- FALSE
32. A single Schmitt trigger inverter is all that is needed to build a simple astable multivibrator.
- TRUE
- FALSE
34. When the 74123, a retriggerable monostable multivibrator device, ends its timing cycle it must be started all over again.
- TRUE
- FALSE
35. A multivibrator is a circuit that changes between two digital levels on a continuous, free-running basis or on demand.
- TRUE
- FALSE
37. On the fifth clock pulse, a 4-bit Johnson sequence is Q0 = 0, Q1 = 1, Q2 = 1, and Q3 = 1. On the sixth clock pulse, the sequence is ________.
- Q0 = 1, Q1 = 0, Q2 = 0, Q3 = 0
- Q0 = 1, Q1 = 1, Q2 = 1, Q3 = 0
- Q0 = 0, Q1 = 0, Q2 = 1, Q3 = 1
- Q0 = 0, Q1 = 0, Q2 = 0, Q3 = 1
38. The bit sequence 0010 is serially entered (right-most bit first) into a 4-bit parallel out shift register that is initially clear. What are the Q outputs after two clock pulses?
- 0000
- 0010
- 1000
- 1111
39. What is a shift register that will accept a parallel input, or a bidirectional serial load and internal shift features, called?
- tristate
- end around
- universal
- conversion
40. On the third clock pulse, a 4-bit Johnson sequence is Q0 = 1, Q1 = 1, Q2 = 1, and Q3 = 0. On the fourth clock pulse, the sequence is ________.
- Q0 = 1, Q1 = 1, Q2 = 1, Q3 = 1
- Q0 = 1, Q1 = 1, Q2 = 0, Q3 = 0
- Q0 = 1, Q1 = 0, Q2 = 0, Q3 = 0
- Q0 = 0, Q1 = 0, Q2 = 0, Q3 = 0