11. Which of the following multivibrator is called the flip flop?
Astable multivibrator
Monostable multivibrator
Bistable multivibrator
Both (b) and (c)
Answer.3. Bistable multivibrator
Flips-Flops are synchronous bistable devices, also known as bistable multivibrators.
Synchronous means, output changes state only at a specified point on a triggering input called clock (CLK), which is designated as a control input.
Types:
S-R Flip Flop
J-K Flip Flop
D Flip Flop
12. Sawtooth wave can be generated through the ____
Schmitt trigger
Hartley oscillator
Colpitts oscillator
Crystal oscillator
Answer.1. Schmitt trigger
A Schmitt trigger is basically an inverting comparator circuit with positive feedback.
The function of the Schmitt trigger is to convert any regular or irregular-shaped input waveform into a square wave output voltage or pulse.
The Triangular wave generator can be converted into a saw-tooth wave generator by injecting variable DC voltage into the non-inverting terminal of the integrator.
13. A Schmitt trigger is a digital circuit that produces
triangular output for sinusoidal input
sinusoidal output for any type of input
trapezoidal output for any type of input
rectangular output for any type of input
Answer.4. rectangular output for any type of input
A Schmitt trigger is basically an inverting comparator circuit with positive feedback.
The function of the Schmitt trigger is to convert any regular or irregular-shaped input waveform into a square wave output voltage or pulse.
Thus, it can shape a wave and also called a squaring circuit, and can be used as a square wave generator.
A Schmitt trigger is a digital circuit that produces rectangular output for any type of input
14. In the astable multivibrator circuit shown in the figure, the frequency of oscillation (in kHz) at the output pin 3 is __________
6.12 kHz
5.65 kHz
3.25 kHz
4.65 kHz
Answer.2. 5.65 kHz
The given circuit acts as an astable multivibrator.
The ON and OFF time are given by:
TON = 0.693 (RA + RB) C and
TOFF = 0.693RB.C
The total time T = TON + TOFF
T = 0.693 (RA + 2RB) C
Calculation:
Putting on the respective values, we get:
T = 0.693 (2.2 + 9.4) × 103 × 0.022 × 10-6
T = 1.769 × 10-4 sec
Now, the frequency of oscillations will be:
f = 1/T = 5.65 kHz
15. A bistable multi-vibrator that functions as a voltage comparator with hysteresis are called
T flip-flop
D flip-flop
J-K flip-flop
Schmitt trigger
Answer.4. Schmitt triggert
A bistable multi-vibrator that functions as a voltage comparator with hysteresis is called a Schmitt trigger
16. For which of the following functions can a Schmitt trigger be used?
Pulse shaping
Blocking
Amplification
Filtering
Answer.1. Pulse shaping
A Schmitt trigger can be used for Pulse shaping.
A Schmitt trigger is a comparator circuit with hysteresis implemented by applying positive feedback to the noninverting input of a comparator or differential amplifier.
In the non-inverting configuration, when the input is higher than a chosen threshold, the output is high.
When the input is below a different (lower) chosen threshold the output is low, and when the input is between the two levels the output retains its value.
if we use the Schmitt Trigger for the noisy input signal we will get a correct input of two pulses because of the two different thresholds.
17. In order to obtain repetitive pulses of unequal mark space durations one can use
1. A voltage comparator fed with a triangular wave signal and a dc voltage.
2. An astable multi-vibrator.
3. A mono-stable multi-vibrator fed with a square wave input.
4. Both 1 and 3
Answer.4. Both 1 and 3
With voltage comparator having triangular wave, we observe the only repetitive pulse of equal mark space, because of DC voltage along with triangular wave we observe unequal mark space at the output.
With an astable multivibrator, we can see only a repetitive pulse of equal mark space, without any trigger input.
A monostable multivibrator can produce one stable output and hence to toggle the state we require trigger input and therefore it produces a repetitive pulse of unequal width.
18. The function of the Schmitt trigger is
To divide frequency
To control frequency
To shape a wave
To give out a sawtooth wave
Answer.3. To shape a wave
A Schmitt trigger is basically an inverting comparator circuit with positive feedback.
The function of the Schmitt trigger is to convert any regular or irregular-shaped input waveform into a square wave output voltage or pulse.
Thus, it can shape a wave and also called a squaring circuit, and can be used as a square wave generator.
19. Schmitt trigger may be used to
change voltage to the corresponding frequency
change frequency to voltage
change a slowly varying voltage to square voltage
none of these
Answer.3. change a slowly varying voltage to square voltage
Schmitt trigger is basically an inverting comparator circuit with positive feedback. The purpose of the Schmitt trigger is to convert any regular or irregular-shaped input waveform into a square wave output voltage or pulse. Thus, it can also be called a squaring circuit.
