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UNIT-V – FEEDBACK AMPLIFIERS AND OSCILLATORS
1.What are the types of Mutivibrators
The three types of mutivibrators are
1. bistable :It has tow stable states.
2. It has one stable state.
3. It has tow states both are quasi-stable.
2.What is intrinsic standoff ratio of a UJT
Intrinsic stand-off ratio of UJT indicates that the transistor internally divides the
supply voitage and bias the emitter terminal.It is the ratio of the stand off voltage to the
power supply voltage.
3. What is a clamper? Name it’s types?
The ciricuit which is used to add a d.c lever as Per the requirements to the a.c output
signal is called Clamper circuit. The two types are positive clamper and negativeClamper.
4. How is a Schmitt trigger different from a multivibrator?
A Schmitt trigger isa thres hold circuit which uses Positive feedback with loop gain
greater than unity.The Schmitt trigger is a comparator which switches the output positive
when the input passes upward.
5. Mention some applications of UJT
1. used in triggering of another device such as SCR.
2. AS a relaxation oscillator
6. Write the frequency equation of an Astable Multivibrator.
The frequency equation is T=0.69R,C, and T2=0.69R2c2
While T=T1+T2
F=1/T=1/0.69CR1C1+R2(2)
7. What is Schmitt trigger?
A Schmitt trigger is a threshond circuit which Uses positive feedback with loop gain
greater than Unity.
8. What is a Multivibrator?
A multivibrator is an electronic circuit using two Amplifying transistor stages each
with its output Connected to the input of the other by resistors and capacitors.
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9. What is clipper?
The circuit which is used to clip off unwanted Portion of the waveform without
distorting the remaining Part of the waveform is called clipper circuit.
10. Under what condition would a Schmitt trigger operate as an amplifier?
The resistance Rc1 must be enough smaller than Rc2 So that regeneration cannot take
place and Schmitt Trigger operates as an amplifier.
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