UNIT-IV
WAVE SHAPING AND MULTIVIBRATOR CIRCUITS
PART – A
1. What is a Clamper? What are its uses? (NOV2011, MAY 2012)
A clamper is a circuit which shifts (clamps) a signal to a different dc level, ie., it introduces a dc level to an ac signal. The clamper is also known as dc restorer. It is used in television receivers to restore the dc reference signal to the video signal.
2. State the basic action of monostable multivibrator. (APR-2003)
Monostable multivibrator is also known as one-shot multivibrator or univibrator. It has one stable state and one quasi-stable state. When an external trigger pulse is applied to the circuit, the circuit goes into the quasi-stable state from its normal stable state. After some time interval, the circuit automatically returns to its stable state.The circuit does not require any external pulse to change from quasi-stable state to stable state. The time interval for which the circuit remains in the quasi-stable state is determined by the circuit components and can be designed as per the requirement.
3. What is Astable multivibrator? (NOV 2010)
An astable or free-running multivibrator generates square wave without any external triggering pulse. It has no stable states, ie., it has two quasi-stable states. It switches back and forth from one state to the other, remaining in each state for a time depending upon the discharging of a capacitive circuit.
4. Where are bistable multivibrator applied? or State the applications of bistable multivibrator ? (JUN 2007 & MAY 2011)
a)Memory element in shift register, counters and so on. b)To generate square wave of symmetrical shape by sending regular triggering pulse to the input.
c)It is used as a frequency divider.
5. What are the applications of Monostable multivibrator? (DEC-2007)
1. It is used to function as an adjustable pulse width generator.
2. It is used to generate uniform width pulses from a variable width input pulse train.
6. What is meant by unsymmetrical triggering? (NOV-2005)
This method uses two triggering inputs. The triggering signal from the first input is applied to set the circuit in one particular state. The triggering signal from the second input is applied to reset the circuit to the opposite state. This process is called set-reset triggering. The unsymmetrical triggering is used in register and coding circuits.
7. What is meant by symmetrical triggering?
In symmetrical triggering method, each successive triggering signal changes the state of the flip-flop. It is used in binary counting circuits.
8. What is the frequency of oscillation of astable multivibrator? (NOV-2005)
Time period=T=1.4RC , Frequency of oscillation=1/T=1/1.4RC
9. What are the advantages of dc-flip-flop? (OCT-2004)
Extreme simplicity, Low power dissipation, Transistor with low breakdown voltages are used, one supply voltage of low value
10. What are applications of Schmitt trigger?(DEC 2007 & NOV 2010, MAY 2012)
a) It is used for wave shaping circuits and as a voltage comparator
b) It is used for the generation of rectangular waveform with sharp edges from a sine wave or any other waveform
c) It can be used as a voltage comparator.
d) Triggering can be made more sensitive to small noise fluctuations present in the input signal.
11. Define Schmitt trigger. (JUN-2006)
Schmitt trigger is a wave shaping circuit, used for generation of a square from a sine wave input. It is a bistable circuit in which two transistor switches are connected regeneratively.
12. Compare the transistors used in multivibrator circuits with those that are used in conventional amplifiers? (DEC 2004)
In the multivibrators, the transition of transistor states from ON to OFF and OFF to ON is important. To avoid the distortion, this transistion must be as fast as possible.Hence the transistors used in multivibrators have small switching times ie.,small turn on and turn off times as compared to those used in conventional circuits. Such transistors are called switching transistors.
13. State the roe of commutating capacitors in Bistable multivibrator. (JUN-2009)
In bistable multivibrator,trigger is required to change the state. The time required to change the state is called the transistion time.The speed-up capacitors are used to reduce the transition time without affecting the stable states.These capacitots allow fast rise and fall times and avoids the distortion in the output.
14. State the expression for gate width of monostable multivibrator. (JUN 2009)
T = τ ln(2)
The time constant τ for the charging path of capacitor C is RC, So,T=0.69RC.Thus the gate width is independent of transistor characteristics, supply voltage and resistance value.
15. Define quasi stable state. (MAY 2010)
The stable state of monostable multivibrator in which circuit remains for some time and returns to stable state,is called Quasi stable state.
16. Differentiate clippers from clampers. (MAY2010)
CLIPPERS CLAMPERS
The circuit with which the waveform is shaped by removing (or clipping) a portion of the input signal without distorting the remaining part of the alternating waveform is called a clipper A clamper is a circuit which shifts (clamps) a signal to a different dc level, ie., it introduces a dc level to an ac signal.
17. Draw the circuit of an integrator using Rand C as circuit elements and find its output voltage V0, if Vi is the input voltage. (MAY 2011)
V0=1 /RC ∫Vi dt
V0=Vi [1-e-t/RC]
18. Why is monostable multivibrator is called delay circuit? (MAY 2011)
The time between the trasistion from quasi –stable state to stable state can be pre determined and hence I can be used to introduce time delays with the help of fast transition. Due to this application, it is called as delay circuit.
19. What is self biased multivibrator? (MAY2011)
If the multivibrator automatically makes the successive transitions from one quasi – stable state to other without any external triggering pulse., then it is known as self-biased multivibrator. Ex: Astable Multivibrator.
20. What is free running multivibrator (NOV 2010)
An astable or free-running multivibrator generates square wave without any external triggering pulse. It has no stable states, ie., it has two quasi-stable states. It switches back and forth from one state to the other, remaining in each state for a time depending upon the discharging of a capacitive circuit.
21. What is linear wave shaping?
The process by which the shape of a nonsinusoidal signal is changed by passing the signal through the network consisting of linear elements is called linear wave shaping.
22. Mention the various nonsinusoidal waveforms.
1.Step 2.Pulse 3.Square 4.Ramp
23. What is high pass RC circuit?(or)What is a differentiator? Explain its feature and use.
A circuit which consists of a series capacitor and a shunt resistor is called a differentiating or high pass RC circuit. At very high frequencies, the capacitor acts as a short circuit and all the higher frequency components appear at the output with less attenuation than the lower frequency components. Hence this circuit is called high- pass filter. Due to this feature, it is used as coupling circuit to provide dc isolation between input and output.
24. What is low pass RC circuit? (or)What is an integrator? Explain its feature and use.
A circuit which consists of a series resistor and a shunt capacitor is called an integrator or low pass RC circuit. At very high frequencies, the capacitor acts as a virtual short circuit and the output falls to zero. Hence this circuit is called low - pass filter. Due to this feature, it is used when it is required to extend the range of operation of some electronic circuit to a higher frequency.
25. What is tilt or sag?
The decay in the amplitude of the output voltage waveform when the input level is maintained constant is called tilt or sag or decay.
26. Define Duty cycle.
It is the ratio of the ON period (TON) to the total period (T = TON + TOFF).Therefore duty cycle = TON / T.
27. Define Rise time.
It is the time required by the output response to rise from 10% to 90% of its maximum value.
28. Define Delay time.
In a transistor switching circuit, the collector current(output response) does not immediately respond to the input pulse. There is a delay and the time that elapses during this delay together with time needed for the current to rise to 10% of its maximum(saturation) value ie., IC(Sat)= VCC/RC is called the delay time.
29. Define Fall time.
It is the time required by the output response to fall from 90% to 10% of its maximum value.
30. Define storage time.
When the input signal returns back to its initial state at t = T, the collector current gain fails to respond immediately. The interval which elapses between the transition of the input voltage waveform and the time when collector current (ic) dropped to 90% of its maximum value is called the storage time.
31. Define speedup capacitor.
Speedup capacitors or commutating, transpose capacitors are small capacitors introduced in shunt with the coupling resistors of the binary of a switching circuit in order to reduce the transition time. Since these capacitors assist the binary in making abrupt transition between starter, they are known as speedup capacitors.
32. What is clipper circuit?
The circuit with which the waveform is shaped by removing (or clipping) a portion of the input signal without distorting the remaining part of the alternating waveform is called a clipper.Clippers are also called as limiters, amplitude selectors or slicers.
33. What are the types of clippers?
1.Positive Clipper 2.Negative Clipper 3.Biased Clipper 4.Combination Clipper.
34. What are the uses of clippers?
Clippers are used in radars, digital computers, radio and television receivers.
35. What are the types of Clampers?
1. Positive clamper 2. Negative clamper
36. What is a diode comparator?
A nonlinear circuit which is used to compare an input signal Vi(t) with a reference voltage VR. The comparator output is independent of the signal until it attains the reference level. When the signal and reference level become equal, there will be a sharp pulse at the comparator output.
37. Define Multivibrator.
A multivibrator is a two stage switching circuits in which the output of the first stage is fed to the input of the second stage and vice-versa. The outputs of two stages are complementary.
38. What are the various types of multivibrator?
There are three types of multivibrator. 1. Bistable multivibrator 2.Monostable multivibrator 3.Astable multivibrator.
39. What is bistable multivibrator?
A bistable multivibrator has two stable states. The multivibrator can exist indefinitely in either of the two stable states. It requires an external trigger pulse to change from one stable state to another.The circuit remains in one stable state unless an external trigger pulse is applied.The bistable multivibrator is also referred as flip- flop, Eccles-Jordon circuit,trigger circuit or binary.
40. What are the applications of Astable multivibrator?
1. Used as square wave generator, voltage to frequency converter and in pulse synchronization, as clock for binary logic signals, and so on.
2. Since it produces square waves, it is a source of production of harmonic frequencies of higher order.
3. Used in the construction of digital voltmeters and SMPS.
4. Can be operated as an oscillator over a wide range of audio and radio frequencies.
41. What is meant by triggering of multivibrator?
To provide proper pulse input to achieve a transistion from one state to the other state of the multivibrator,is called the triggering of multivibrators.
42. Define UTP and LTP.
UTP is a point at which the transistor enters into conduction state i.e. from OFF to ON state. LTP is a point at which the transistor enters from ON to OFF state.
43. What is hysteresis voltage and hysteresis in Schmitt trigger?
The difference between UTP and LTP is known as hysteresis voltage(VH). VH is also known as Dead zone of the Schmitt Trigger. The lagging of the lower threshold voltage from the upper threshold voltage is known as hysteresis.
44. What is the difference between an oscillator and multivibrator?
Multivibrator operates in non linear region of transfer characteristics and oscillator operates in linear or active region of its transfer characteristics.
45. Give the expansions of UTL, UTP, LTL, LTP.
UTL - upper trigger level UTP - upper trigger point
LTL - lower trigger level LTP - Lower trigger point
46. What are the other names of monostable multivibrator?
It is commonly known as oneshot,single cycle, a single step circuit or univibrator.
.
47. What is a differentiator? Explain its feature and use.
A circuit which consists of a series capacitor and a shunt resistor is called a differentiating or high pass RC circuit. At very high frequencies, the capacitor acts as a short circuit and all the higher frequency components appear at the output with less attenuation than the lower frequency components. Hence this circuit is called high- pass filter. Due to this feature, it is used as coupling circuit to provide dc isolation between input and output.
48. What is bistable multivibrator?
A bistable multivibrator has two stable states. The multivibrator can exist indefinitely in either of the two stable states. It requires an external trigger pulse to change from one stable state to another.The circuit remains in one stable state unless an external trigger pulse is applied.The bistable multivibrator is also referred as flip- flop, Eccles-Jordon circuit,trigger circuit or binary.
49. What is an integrator? Explain its feature and use.
A circuit which consists of a series resistor and a shunt capacitor is called an integrator or low pass RC circuit. At very high frequencies, the capacitor acts as a virtual short circuit and the output falls to zero. Hence
this circuit is called low - pass filter. Due to this feature, it is used when it is required to extend the range of operation of some electronic circuit to a higher frequency.
50. Define UTP .
UTP is a point at which the transistor enters into conduction state i.e. from OFF to ON state.
PART – B
1. How high pass RC circuit be used as a differentiator? (MAY 2006)
2. How low pass RC circuit be used as a integrator? (DEC 2004)
3. Define and illustrate the following nonsinusoidal waveforms:1.Step 2.Pulse 3.Square 4.Ramp
4 .Derive and draw the response of high pass and low pass RC circuit to following waveforms:
1. Step 2.Pulse 3.Square 4.Ramp (JUN 2006, MAY 2012)
5. With circuit diagram and waveforms explain the operation of RC circuits as Integrators and Differentiators for square wave input.
6. Explain how RC circuits are used as integrators and differentiators. Sketch the output for a square wave input.
7. Draw the circuit diagram of an emitter-coupled monostable multivibrator and explain its operation with relevant waveforms. (JUN 2006)
8. Explain the unsymmetrical triggering and symmetrical triggering of bistable multivibrator. (DEC 2007)
9. Draw the circuit diagram of an emitter coupled astable multivibrator. (DEC-2009, NOV 2011)
10. Design a monostable multivibrator for the following specifications: VCC = 10 V,VBB = 6 V, IC(on) = 1 mA, duration of output pulse = 14 seconds,hFEmin = 100, ICBO = 0,VBE(off) = -0.5V.
11. Design a Schmitt trigger circuit for VCC = 10 V, UTP = 5V, LTP = 3V. Assume hFEmin = 100 and IC(on) =1 mA.
12. Design a collector coupled astable multivibrator for the following specifications: Output voltage 10V peak,IC(on) =1 mA, hFEmin = 100, ICBO = 0, output to be a positive pulse, the duration of which is 20µsec,the time between pulses to be 10 µsec. (MAY 2004)
13. With circuit diagram and waveforms explain the operation of a Schmitt trigger using two transistors for a sinusoidal input.(MAY 2010, 2011 & NOV 2010, MAY 2012)
14. With circuit diagram and necessary waveforms, explain the operation of a saturated collector coupled astable multivibrator. (DEC 2008)
15. With circuit diagram and necessary waveforms, explain the operation of a saturated collector coupled monostable multivibrator. (DEC 2008)
16. Explain the effect of emitter coupling in monostable multivibrator.(JUN 2006)
17. Explain the ON and OFF state of the transistors in a collector coupled symmetrical triggered Bistable multivibrator. (JUN 2006)
18. Explain the effect of speed up capacitor in bistable multivibrator.(JUN 2006)
19. Determine the value of capacitors to be used in an astable multivibrator to provide a train of pulse 2µs wide at a repetition rate of 100KHz if R1=R2=20KΏ. (JUN 2009, MAY 2012)
20. Explain circuits used to trigger a transistor monostable multivibrator circuit (DEC 2008)
21. Describe the parallel biased clipper operation with necessary diagrams. (MAY 2010)
22. Design and draw a saturated collector coupled monostable multivibrator for the following specifications: Vcc=10V, Vbb=5V, pulse duration=12ms, Ic=2mA and hfe=100. (MAY 2011)
23. A 10 Hz symmetrical square wave, with a peak to peak amplitude of 2 V, is impressed upon a high pass RC circuit whose 3-dB frequency is 5 Hz. Calculate and sketch the output waveform. What is the peak to peak output amplitude? (MAY 2012)
24. Explain schmitt circuit as (i) Amplitude comparator (2) Squaring Circuit (3) Flip-flop circuit. (NOV 2011)
WAVE SHAPING AND MULTIVIBRATOR CIRCUITS
PART – A
1. What is a Clamper? What are its uses? (NOV2011, MAY 2012)
A clamper is a circuit which shifts (clamps) a signal to a different dc level, ie., it introduces a dc level to an ac signal. The clamper is also known as dc restorer. It is used in television receivers to restore the dc reference signal to the video signal.
2. State the basic action of monostable multivibrator. (APR-2003)
Monostable multivibrator is also known as one-shot multivibrator or univibrator. It has one stable state and one quasi-stable state. When an external trigger pulse is applied to the circuit, the circuit goes into the quasi-stable state from its normal stable state. After some time interval, the circuit automatically returns to its stable state.The circuit does not require any external pulse to change from quasi-stable state to stable state. The time interval for which the circuit remains in the quasi-stable state is determined by the circuit components and can be designed as per the requirement.
3. What is Astable multivibrator? (NOV 2010)
An astable or free-running multivibrator generates square wave without any external triggering pulse. It has no stable states, ie., it has two quasi-stable states. It switches back and forth from one state to the other, remaining in each state for a time depending upon the discharging of a capacitive circuit.
4. Where are bistable multivibrator applied? or State the applications of bistable multivibrator ? (JUN 2007 & MAY 2011)
a)Memory element in shift register, counters and so on. b)To generate square wave of symmetrical shape by sending regular triggering pulse to the input.
c)It is used as a frequency divider.
5. What are the applications of Monostable multivibrator? (DEC-2007)
1. It is used to function as an adjustable pulse width generator.
2. It is used to generate uniform width pulses from a variable width input pulse train.
6. What is meant by unsymmetrical triggering? (NOV-2005)
This method uses two triggering inputs. The triggering signal from the first input is applied to set the circuit in one particular state. The triggering signal from the second input is applied to reset the circuit to the opposite state. This process is called set-reset triggering. The unsymmetrical triggering is used in register and coding circuits.
7. What is meant by symmetrical triggering?
In symmetrical triggering method, each successive triggering signal changes the state of the flip-flop. It is used in binary counting circuits.
8. What is the frequency of oscillation of astable multivibrator? (NOV-2005)
Time period=T=1.4RC , Frequency of oscillation=1/T=1/1.4RC
9. What are the advantages of dc-flip-flop? (OCT-2004)
Extreme simplicity, Low power dissipation, Transistor with low breakdown voltages are used, one supply voltage of low value
10. What are applications of Schmitt trigger?(DEC 2007 & NOV 2010, MAY 2012)
a) It is used for wave shaping circuits and as a voltage comparator
b) It is used for the generation of rectangular waveform with sharp edges from a sine wave or any other waveform
c) It can be used as a voltage comparator.
d) Triggering can be made more sensitive to small noise fluctuations present in the input signal.
11. Define Schmitt trigger. (JUN-2006)
Schmitt trigger is a wave shaping circuit, used for generation of a square from a sine wave input. It is a bistable circuit in which two transistor switches are connected regeneratively.
12. Compare the transistors used in multivibrator circuits with those that are used in conventional amplifiers? (DEC 2004)
In the multivibrators, the transition of transistor states from ON to OFF and OFF to ON is important. To avoid the distortion, this transistion must be as fast as possible.Hence the transistors used in multivibrators have small switching times ie.,small turn on and turn off times as compared to those used in conventional circuits. Such transistors are called switching transistors.
13. State the roe of commutating capacitors in Bistable multivibrator. (JUN-2009)
In bistable multivibrator,trigger is required to change the state. The time required to change the state is called the transistion time.The speed-up capacitors are used to reduce the transition time without affecting the stable states.These capacitots allow fast rise and fall times and avoids the distortion in the output.
14. State the expression for gate width of monostable multivibrator. (JUN 2009)
T = τ ln(2)
The time constant τ for the charging path of capacitor C is RC, So,T=0.69RC.Thus the gate width is independent of transistor characteristics, supply voltage and resistance value.
15. Define quasi stable state. (MAY 2010)
The stable state of monostable multivibrator in which circuit remains for some time and returns to stable state,is called Quasi stable state.
16. Differentiate clippers from clampers. (MAY2010)
CLIPPERS CLAMPERS
The circuit with which the waveform is shaped by removing (or clipping) a portion of the input signal without distorting the remaining part of the alternating waveform is called a clipper A clamper is a circuit which shifts (clamps) a signal to a different dc level, ie., it introduces a dc level to an ac signal.
17. Draw the circuit of an integrator using Rand C as circuit elements and find its output voltage V0, if Vi is the input voltage. (MAY 2011)
V0=1 /RC ∫Vi dt
V0=Vi [1-e-t/RC]
18. Why is monostable multivibrator is called delay circuit? (MAY 2011)
The time between the trasistion from quasi –stable state to stable state can be pre determined and hence I can be used to introduce time delays with the help of fast transition. Due to this application, it is called as delay circuit.
19. What is self biased multivibrator? (MAY2011)
If the multivibrator automatically makes the successive transitions from one quasi – stable state to other without any external triggering pulse., then it is known as self-biased multivibrator. Ex: Astable Multivibrator.
20. What is free running multivibrator (NOV 2010)
An astable or free-running multivibrator generates square wave without any external triggering pulse. It has no stable states, ie., it has two quasi-stable states. It switches back and forth from one state to the other, remaining in each state for a time depending upon the discharging of a capacitive circuit.
21. What is linear wave shaping?
The process by which the shape of a nonsinusoidal signal is changed by passing the signal through the network consisting of linear elements is called linear wave shaping.
22. Mention the various nonsinusoidal waveforms.
1.Step 2.Pulse 3.Square 4.Ramp
23. What is high pass RC circuit?(or)What is a differentiator? Explain its feature and use.
A circuit which consists of a series capacitor and a shunt resistor is called a differentiating or high pass RC circuit. At very high frequencies, the capacitor acts as a short circuit and all the higher frequency components appear at the output with less attenuation than the lower frequency components. Hence this circuit is called high- pass filter. Due to this feature, it is used as coupling circuit to provide dc isolation between input and output.
24. What is low pass RC circuit? (or)What is an integrator? Explain its feature and use.
A circuit which consists of a series resistor and a shunt capacitor is called an integrator or low pass RC circuit. At very high frequencies, the capacitor acts as a virtual short circuit and the output falls to zero. Hence this circuit is called low - pass filter. Due to this feature, it is used when it is required to extend the range of operation of some electronic circuit to a higher frequency.
25. What is tilt or sag?
The decay in the amplitude of the output voltage waveform when the input level is maintained constant is called tilt or sag or decay.
26. Define Duty cycle.
It is the ratio of the ON period (TON) to the total period (T = TON + TOFF).Therefore duty cycle = TON / T.
27. Define Rise time.
It is the time required by the output response to rise from 10% to 90% of its maximum value.
28. Define Delay time.
In a transistor switching circuit, the collector current(output response) does not immediately respond to the input pulse. There is a delay and the time that elapses during this delay together with time needed for the current to rise to 10% of its maximum(saturation) value ie., IC(Sat)= VCC/RC is called the delay time.
29. Define Fall time.
It is the time required by the output response to fall from 90% to 10% of its maximum value.
30. Define storage time.
When the input signal returns back to its initial state at t = T, the collector current gain fails to respond immediately. The interval which elapses between the transition of the input voltage waveform and the time when collector current (ic) dropped to 90% of its maximum value is called the storage time.
31. Define speedup capacitor.
Speedup capacitors or commutating, transpose capacitors are small capacitors introduced in shunt with the coupling resistors of the binary of a switching circuit in order to reduce the transition time. Since these capacitors assist the binary in making abrupt transition between starter, they are known as speedup capacitors.
32. What is clipper circuit?
The circuit with which the waveform is shaped by removing (or clipping) a portion of the input signal without distorting the remaining part of the alternating waveform is called a clipper.Clippers are also called as limiters, amplitude selectors or slicers.
33. What are the types of clippers?
1.Positive Clipper 2.Negative Clipper 3.Biased Clipper 4.Combination Clipper.
34. What are the uses of clippers?
Clippers are used in radars, digital computers, radio and television receivers.
35. What are the types of Clampers?
1. Positive clamper 2. Negative clamper
36. What is a diode comparator?
A nonlinear circuit which is used to compare an input signal Vi(t) with a reference voltage VR. The comparator output is independent of the signal until it attains the reference level. When the signal and reference level become equal, there will be a sharp pulse at the comparator output.
37. Define Multivibrator.
A multivibrator is a two stage switching circuits in which the output of the first stage is fed to the input of the second stage and vice-versa. The outputs of two stages are complementary.
38. What are the various types of multivibrator?
There are three types of multivibrator. 1. Bistable multivibrator 2.Monostable multivibrator 3.Astable multivibrator.
39. What is bistable multivibrator?
A bistable multivibrator has two stable states. The multivibrator can exist indefinitely in either of the two stable states. It requires an external trigger pulse to change from one stable state to another.The circuit remains in one stable state unless an external trigger pulse is applied.The bistable multivibrator is also referred as flip- flop, Eccles-Jordon circuit,trigger circuit or binary.
40. What are the applications of Astable multivibrator?
1. Used as square wave generator, voltage to frequency converter and in pulse synchronization, as clock for binary logic signals, and so on.
2. Since it produces square waves, it is a source of production of harmonic frequencies of higher order.
3. Used in the construction of digital voltmeters and SMPS.
4. Can be operated as an oscillator over a wide range of audio and radio frequencies.
41. What is meant by triggering of multivibrator?
To provide proper pulse input to achieve a transistion from one state to the other state of the multivibrator,is called the triggering of multivibrators.
42. Define UTP and LTP.
UTP is a point at which the transistor enters into conduction state i.e. from OFF to ON state. LTP is a point at which the transistor enters from ON to OFF state.
43. What is hysteresis voltage and hysteresis in Schmitt trigger?
The difference between UTP and LTP is known as hysteresis voltage(VH). VH is also known as Dead zone of the Schmitt Trigger. The lagging of the lower threshold voltage from the upper threshold voltage is known as hysteresis.
44. What is the difference between an oscillator and multivibrator?
Multivibrator operates in non linear region of transfer characteristics and oscillator operates in linear or active region of its transfer characteristics.
45. Give the expansions of UTL, UTP, LTL, LTP.
UTL - upper trigger level UTP - upper trigger point
LTL - lower trigger level LTP - Lower trigger point
46. What are the other names of monostable multivibrator?
It is commonly known as oneshot,single cycle, a single step circuit or univibrator.
.
47. What is a differentiator? Explain its feature and use.
A circuit which consists of a series capacitor and a shunt resistor is called a differentiating or high pass RC circuit. At very high frequencies, the capacitor acts as a short circuit and all the higher frequency components appear at the output with less attenuation than the lower frequency components. Hence this circuit is called high- pass filter. Due to this feature, it is used as coupling circuit to provide dc isolation between input and output.
48. What is bistable multivibrator?
A bistable multivibrator has two stable states. The multivibrator can exist indefinitely in either of the two stable states. It requires an external trigger pulse to change from one stable state to another.The circuit remains in one stable state unless an external trigger pulse is applied.The bistable multivibrator is also referred as flip- flop, Eccles-Jordon circuit,trigger circuit or binary.
49. What is an integrator? Explain its feature and use.
A circuit which consists of a series resistor and a shunt capacitor is called an integrator or low pass RC circuit. At very high frequencies, the capacitor acts as a virtual short circuit and the output falls to zero. Hence
this circuit is called low - pass filter. Due to this feature, it is used when it is required to extend the range of operation of some electronic circuit to a higher frequency.
50. Define UTP .
UTP is a point at which the transistor enters into conduction state i.e. from OFF to ON state.
PART – B
1. How high pass RC circuit be used as a differentiator? (MAY 2006)
2. How low pass RC circuit be used as a integrator? (DEC 2004)
3. Define and illustrate the following nonsinusoidal waveforms:1.Step 2.Pulse 3.Square 4.Ramp
4 .Derive and draw the response of high pass and low pass RC circuit to following waveforms:
1. Step 2.Pulse 3.Square 4.Ramp (JUN 2006, MAY 2012)
5. With circuit diagram and waveforms explain the operation of RC circuits as Integrators and Differentiators for square wave input.
6. Explain how RC circuits are used as integrators and differentiators. Sketch the output for a square wave input.
7. Draw the circuit diagram of an emitter-coupled monostable multivibrator and explain its operation with relevant waveforms. (JUN 2006)
8. Explain the unsymmetrical triggering and symmetrical triggering of bistable multivibrator. (DEC 2007)
9. Draw the circuit diagram of an emitter coupled astable multivibrator. (DEC-2009, NOV 2011)
10. Design a monostable multivibrator for the following specifications: VCC = 10 V,VBB = 6 V, IC(on) = 1 mA, duration of output pulse = 14 seconds,hFEmin = 100, ICBO = 0,VBE(off) = -0.5V.
11. Design a Schmitt trigger circuit for VCC = 10 V, UTP = 5V, LTP = 3V. Assume hFEmin = 100 and IC(on) =1 mA.
12. Design a collector coupled astable multivibrator for the following specifications: Output voltage 10V peak,IC(on) =1 mA, hFEmin = 100, ICBO = 0, output to be a positive pulse, the duration of which is 20µsec,the time between pulses to be 10 µsec. (MAY 2004)
13. With circuit diagram and waveforms explain the operation of a Schmitt trigger using two transistors for a sinusoidal input.(MAY 2010, 2011 & NOV 2010, MAY 2012)
14. With circuit diagram and necessary waveforms, explain the operation of a saturated collector coupled astable multivibrator. (DEC 2008)
15. With circuit diagram and necessary waveforms, explain the operation of a saturated collector coupled monostable multivibrator. (DEC 2008)
16. Explain the effect of emitter coupling in monostable multivibrator.(JUN 2006)
17. Explain the ON and OFF state of the transistors in a collector coupled symmetrical triggered Bistable multivibrator. (JUN 2006)
18. Explain the effect of speed up capacitor in bistable multivibrator.(JUN 2006)
19. Determine the value of capacitors to be used in an astable multivibrator to provide a train of pulse 2µs wide at a repetition rate of 100KHz if R1=R2=20KΏ. (JUN 2009, MAY 2012)
20. Explain circuits used to trigger a transistor monostable multivibrator circuit (DEC 2008)
21. Describe the parallel biased clipper operation with necessary diagrams. (MAY 2010)
22. Design and draw a saturated collector coupled monostable multivibrator for the following specifications: Vcc=10V, Vbb=5V, pulse duration=12ms, Ic=2mA and hfe=100. (MAY 2011)
23. A 10 Hz symmetrical square wave, with a peak to peak amplitude of 2 V, is impressed upon a high pass RC circuit whose 3-dB frequency is 5 Hz. Calculate and sketch the output waveform. What is the peak to peak output amplitude? (MAY 2012)
24. Explain schmitt circuit as (i) Amplitude comparator (2) Squaring Circuit (3) Flip-flop circuit. (NOV 2011)
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