What conditions are required for an amplifier to oscillate A) There must be feedback B) The feedback must be in phase C) The gain must be greater than the loss D) All the above are regd.

What conditions are required for an amplifier to oscillate
A) There must be feedback
B) The feedback must be in phase
C) The gain must be greater than the loss
D) All the above are regd.
by

1 Answer

Answer :

B) The feedback must be in phase
by

Related questions

Which of the following is not true: A) An oscillator is a circuit that converts DC to AC B) An oscillator is an amplifier that supplies its own input signal C) All oscillators generate sine waves D) In phase feedback is called positive Feedback

Description : Which of the following is not true: A) An oscillator is a circuit that converts DC to AC B) An oscillator is an amplifier that supplies its own input signal C) All oscillators generate sine waves D) In phase feedback is called positive Feedback

Last Answer : C) All oscillators generate sine waves

The major function of transistor. Q2 is A) It provides voltage gain B) It provides the feedback signal C) It isolates the oscillator from loading effects D) It provides a phase shift.

Description : The major function of transistor. Q2 is A) It provides voltage gain B) It provides the feedback signal C) It isolates the oscillator from loading effects D) It provides a phase shift.

Last Answer : ) It provides a phase shift.

A series mode crystal is marked 10.000 MHz., It is used in a circuit that operates the crystal in its parallel mode. The circuit can be expected to A) Run below 10 MHz B) Run at 10 MHz C) Run above 10 MHz D) Not oscillate.

Description : A series mode crystal is marked 10.000 MHz., It is used in a circuit that operates the crystal in its parallel mode. The circuit can be expected to A) Run below 10 MHz B) Run at 10 MHz C) Run above 10 MHz D) Not oscillate.

Last Answer : C) Run above 10 MHz

Which amplifier will be preferred for highest gain? A) Darlington's pair B) Cascade amplifier C) Cascode amplifier D) Depends on the circuitry

Description : Which amplifier will be preferred for highest gain? A) Darlington's pair B) Cascade amplifier C) Cascode amplifier D) Depends on the circuitry

Last Answer : C) Cascode amplifier

In a resistance loaded amplifier, the gain decreases a high frequencies because A) Of decreasing reactance of the stray CT B) Increasing reactance of the stray CT C) Increasing reactance of CC D) Decreasing reactance of CC.

Description : In a resistance loaded amplifier, the gain decreases a high frequencies because A) Of decreasing reactance of the stray CT B) Increasing reactance of the stray CT C) Increasing reactance of CC D) Decreasing reactance of CC.

Last Answer : D) Decreasing reactance of CC.

Which of the following contributes to harmonics distortion in amplifiers? A) Positive feedback B) Presence of noise C) Defective active device D) Non linearity in active device.

Description : Which of the following contributes to harmonics distortion in amplifiers? A) Positive feedback B) Presence of noise C) Defective active device D) Non linearity in active device.

Last Answer : D) Non linearity in active device.

In an amplifier if conductor during the cycle is from 0 to 90° and again from 180° to 270°, the amplifier will be termed as A) Class A B) Class B C) Class C D) Class AB.

Description : In an amplifier if conductor during the cycle is from 0 to 90° and again from 180° to 270°, the amplifier will be termed as A) Class A B) Class B C) Class C D) Class AB.

Last Answer : B) Class B

Which of the following methods cannot be used to increase the bandwidth for cascaded RF amplifier stages? A) Wave traps in each stage B) Stagger tuning C) A shunt damping resistor across each tuned circuit D) Doubled tuned transformers with tighter coupling

Description : Which of the following methods cannot be used to increase the bandwidth for cascaded RF amplifier stages? A) Wave traps in each stage B) Stagger tuning C) A shunt damping resistor across each tuned circuit D) Doubled tuned transformers with tighter coupling

Last Answer : A) Wave traps in each stage

A push pull amplifier balances out A) Odd harmonics B) Even harmonics C) Both odd as well as even harmonics D) Neither odd nor even harmonics.

Description : A push pull amplifier balances out A) Odd harmonics B) Even harmonics C) Both odd as well as even harmonics D) Neither odd nor even harmonics.

Last Answer : A) Odd harmonics

In an amplifier the collector voltage equals the full V+ of 28 V instead of the normal 12 V which of the following can be the trouble? A) RL is open B) Cc is open C) RE is open D) CE is shorted.

Description : In an amplifier the collector voltage equals the full V+ of 28 V instead of the normal 12 V which of the following can be the trouble? A) RL is open B) Cc is open C) RE is open D) CE is shorted.

Last Answer : B) Cc is open

An ideal voltage amplifier should have A) Ri = 0, R0 = 0 B) Ri = 0, R0 =∞ C) Ri = ∞, R0 = 0 D) Ri = ∞, R0 = ∞.

Description : An ideal voltage amplifier should have A) Ri = 0, R0 = 0 B) Ri = 0, R0 =∞ C) Ri = ∞, R0 = 0 D) Ri = ∞, R0 = ∞.

Last Answer : C) Ri = ∞, R0 = 0

In a resistance loaded, RC coupled amplifier the dc component is blocked by A) Load resistance RL B) Coupling capacitor, CC C) RB D) The transistor.

Description : In a resistance loaded, RC coupled amplifier the dc component is blocked by A) Load resistance RL B) Coupling capacitor, CC C) RB D) The transistor.

Last Answer : B) Coupling capacitor, CC

If the operating point of an NPN transistor amplifier is selected in saturation region, it is likely to result in A) Thermal runaway of transistor B) Clipping of output in the positive half of the input signal C) Need for high dc collector supply D) Clipping of output in the negative half of the input signal

Description : If the operating point of an NPN transistor amplifier is selected in saturation region, it is likely to result in A) Thermal runaway of transistor B) Clipping of output in the positive half of the ... for high dc collector supply D) Clipping of output in the negative half of the input signal

Last Answer : B) Clipping of output in the positive half of the input signal

Which of the following circuit would be preferred for a 455 kHz IF amplifier? A) A resistance loaded B) Double tuned transformer C) Video amplifier D) Class C

Description : Which of the following circuit would be preferred for a 455 kHz IF amplifier? A) A resistance loaded B) Double tuned transformer C) Video amplifier D) Class C

Last Answer : B) Double tuned transformer

As compared to a CB amplifier, a CE amplifier has A) Lower current amplification B) Higher current amplification C) Higher input resistance. D) Both (B) & (C)

Description : As compared to a CB amplifier, a CE amplifier has A) Lower current amplification B) Higher current amplification C) Higher input resistance. D) Both (B) & (C)

Last Answer : D) Both (B) & (C)

The Bandwidth of an RC-coupled amplifier is limited by: A) coupling capacitors at the low frequency end and bypass capacitors at the high frequency end B) coupling capacitors at the high frequency end and bypass capacitors at the low frequency end C) bypass and coupling capacitors at the low frequency end and shunt capacitors at the high frequency end and D) shunt capacitors at the low frequency end and bypass as well as coupling capacitors at the high frequency end.

Description : The Bandwidth of an RC-coupled amplifier is limited by: A) coupling capacitors at the low frequency end and bypass capacitors at the high frequency end B) coupling capacitors at the high frequency ... at the low frequency end and bypass as well as coupling capacitors at the high frequency end.

Last Answer : C) bypass and coupling capacitors at the low frequency end and shunt capacitors at the high frequency end and

Common base configuration is little used because A) It has low input impedance B) It has high input impedance C) It does not heat up D) It has very high gain.

Description : Common base configuration is little used because A) It has low input impedance B) It has high input impedance C) It does not heat up D) It has very high gain.

Last Answer : A) It has low input impedance

In general, MOV devices are used to protect electronic equipment from dangerous operating conditions such as A) High temperatures B) Line transients C) Over current D) All of the above.

Description : In general, MOV devices are used to protect electronic equipment from dangerous operating conditions such as A) High temperatures B) Line transients C) Over current D) All of the above.

Last Answer : D) All of the above.

Load regulation is a measure of a power supplies ability keep a constant output under conditions of changing A) Line voltage B) Current demand C) Temperature D) Oscillator frequency.

Description : Load regulation is a measure of a power supplies ability keep a constant output under conditions of changing A) Line voltage B) Current demand C) Temperature D) Oscillator frequency.

Last Answer : A) Line voltage

Which distortion is least objectionable in case of audio amplifers? A) Phase distortion B) Frequency distortion C) Harmonic distortion D) Inter modulation distortion.

Description : Which distortion is least objectionable in case of audio amplifers? A) Phase distortion B) Frequency distortion C) Harmonic distortion D) Inter modulation distortion.

Last Answer : A) Phase distortion

Which of the following combinations has no phase inversion of the signal? A) Two CE stages B) CE and CC stages C) Three CE stages D) CE stage and emitter follower.

Description : Which of the following combinations has no phase inversion of the signal? A) Two CE stages B) CE and CC stages C) Three CE stages D) CE stage and emitter follower.

Last Answer : A) Two CE stages

What is the phase relationship of the signal at the collector of Q2 to the signal at the collector of Q, A) 0° B) 90° C) 180° D) 360°.

Description : What is the phase relationship of the signal at the collector of Q2 to the signal at the collector of Q, A) 0° B) 90° C) 180° D) 360°.

Last Answer : C) 180°

For a feedback amplifier, if the loop gain is much greater than unity, the closed loop gain will be equal to

Description : For a feedback amplifier, if the loop gain is much greater than unity, the closed loop gain will be equal to

Last Answer : For a feedback amplifier, if the loop gain is much greater than unity, the closed loop gain will be equal to inverse of feedback factor

The change in base current will be A) 0.66 micro ampere B) 6.6 micro amperes C) 66 micro amperes D) 660 micro amperes.

Description : The change in base current will be A) 0.66 micro ampere B) 6.6 micro amperes C) 66 micro amperes D) 660 micro amperes.

Last Answer : A) 0.66 micro ampere

A IGFET is a A) Linear device B) Square law device C) Half power device D) 3/2 power law device.

Description : A IGFET is a A) Linear device B) Square law device C) Half power device D) 3/2 power law device.

Last Answer : B) Square law device

An FET has a gate source bias of 2 V. The ac input signal is ± 1.2 V. The class of operation is A) A B) B C) C D) AB

Description : An FET has a gate source bias of 2 V. The ac input signal is ± 1.2 V. The class of operation is A) A B) B C) C D) AB

Last Answer : D) AB

The Darlington pair consists of the following two stages A) CE and CC B) Both C) Both CC D) CE and CB

Description : The Darlington pair consists of the following two stages A) CE and CC B) Both C) Both CC D) CE and CB

Last Answer : C) Both CC

Foldback current limiting has the advantage of A) Better pass transistor protection for long term overloads B) A defined turn on point C) Circuit simplicity D) All of the above.

Description : Foldback current limiting has the advantage of A) Better pass transistor protection for long term overloads B) A defined turn on point C) Circuit simplicity D) All of the above.

Last Answer : A) Better pass transistor protection for long term overloads

A crow bar is a power supply circuit that provides A) Conventional current limiting B) Foldback current. limiting C) Temperature control D) Voltage limiting.

Description : A crow bar is a power supply circuit that provides A) Conventional current limiting B) Foldback current. limiting C) Temperature control D) Voltage limiting.

Last Answer : D) Voltage limiting.

Current limited power supplies can prevent damage to A) Rectifier diodes and power transformers. B) Pass transistors C) Other circuits in the system D) All of the above.

Description : Current limited power supplies can prevent damage to A) Rectifier diodes and power transformers. B) Pass transistors C) Other circuits in the system D) All of the above.

Last Answer : D) All of the above.

Six (6) MHz crystal oscillator has a stability of 1 part in 106. The largest frequency error expected of this crystals A) 0.06 Hz B) 0.6 Hz C) 6 Hz D) 60 Hz.

Description : Six (6) MHz crystal oscillator has a stability of 1 part in 106. The largest frequency error expected of this crystals A) 0.06 Hz B) 0.6 Hz C) 6 Hz D) 60 Hz.

Last Answer : C) 6 Hz

An oscillator that uses crystal control should be A) Frequency stable B) useful only at low frequencies C) AVFO D) none of the above.

Description : An oscillator that uses crystal control should be A) Frequency stable B) useful only at low frequencies C) AVFO D) none of the above.

Last Answer : A) Frequency stable

The ideal characteristic of a voltage stablizer is A) constant output voltage with low internal resistance B) constant output current with low internal resistance C) constant output voltage with high internal resistance D) constant internal resistance with variable output voltage.

Description : The ideal characteristic of a voltage stablizer is A) constant output voltage with low internal resistance B) constant output current with low internal resistance C) constant output voltage with high internal resistance D) constant internal resistance with variable output voltage.

Last Answer : A) constant output voltage with low internal resistance

In the illustrated amplifier, the RESET potentiometer A1R2 sets the stability of the control loop by changing the reset time constant. As the potentiometer is turned clockwise _________. EL-0060 A. the gain is increased B. the stability is increased by slowing the response time C. feedback is increased to the summing point at terminal 5 D. response time is increased decreasing stability

Description : In the illustrated amplifier, the RESET potentiometer A1R2 sets the stability of the control loop by changing the reset time constant. As the potentiometer is turned clockwise _________. EL-0060 A. ... is increased to the summing point at terminal 5 D. response time is increased decreasing stability

Last Answer : Answer: B

Basic operating characteristics of the operational amplifier such as gain and stability are the function of its _____________. A. differential input stage B. power output stage C. feedback circuit D. supply voltages

Description : Basic operating characteristics of the operational amplifier such as gain and stability are the function of its _____________. A. differential input stage B. power output stage C. feedback circuit D. supply voltages

Last Answer : Answer: C

Which feedback increases the gain of the amplifier?

Description : Which feedback increases the gain of the amplifier?

Last Answer : Positive feedback

Which feedback decreases the gain of the amplifier?

Description : Which feedback decreases the gain of the amplifier?

Last Answer : Negative feed back

An amplifier without feedback has a voltage gain of 50, input resistance 1kΩ and output resistance of 2.5kΩ.

Description : An amplifier without feedback has a voltage gain of 50, input resistance 1kΩ and output resistance of 2.5kΩ. The input resistance of the current-shunt negative feedback amplifier using the above amplifier with a feedback factor of 0.2 would be: (1) 1/11 kΩ (2) 1/5 kΩ (3) 5 kΩ (4) 11 kΩ

Last Answer : An amplifier without feedback has a voltage gain of 50, input resistance 1kΩ and output resistance of 2.5kΩ. The input resistance of the current-shunt negative feedback amplifier using the above amplifier with a feedback factor of 0.2 would be: 1/11 kΩ

If the feedback factor of an amplifier is 0.1 and its gain without feedback is 40, then its gain with feedback is

Description : If the feedback factor of an amplifier is 0.1 and its gain without feedback is 40, then its gain with feedback is (a) – 13.3 (b) 200 (c) 8 (d) 10 

Last Answer : If the Feedback Factor of an amplifier is 0.1 and its gain without feedback is 40, then feedback is 40,then its gain with feedback is 8.

An amplifier without feedback has a gain of 1000. The gain with a negative feedback of 0.009 is

Description : An amplifier without feedback has a gain of 1000. The gain with a negative feedback of 0.009 is  A) 10 B) 100 C) 125 D) 900

Last Answer : 100

An amplifier has a voltage gain of 120. To reduce distortion, 10% negative feedback is employed. The gain of

Description : An amplifier has a voltage gain of 120. To reduce distortion, 10% negative feedback is employed. The gain of the amplifier with feedback is  (1) 141 (2) 92.3 (3) 9.23 (4) 1.41

Last Answer : An amplifier has a voltage gain of 120. To reduce distortion, 10% negative feedback is employed. The gain of the amplifier with feedback is 9.23

Mark correct option related to packet of regd news paper a) Breach of conditions the packet will not be forwarded but will be returned to sender. b) Sender will be required to pay double deficiency in the internal postage c) If the sender wish to repost the article after complying with necessary conditions, he may do so by paying fresh postage in full on the article. d) All the above are correct

Description : Mark correct option related to packet of regd news paper a) Breach of conditions the packet will not be forwarded but will be returned to sender. b) Sender will be required to pay double deficiency in the ... may do so by paying fresh postage in full on the article. d) All the above are correct

Last Answer : d) All the above are correct

Equilibrium relates to which of these (a) Market condition which oscillate ; (b) Market state of falling price; (c) Market condition of rising price ; (d) Market conditions which once achieved tends to persist

Description : Equilibrium relates to which of these (a) Market condition which oscillate ; (b) Market state of falling price; (c) Market condition of rising price ; (d) Market conditions which once achieved tends to persist

Last Answer :  (d) Market conditions which once achieved tends to persist

During free vibration, different degrees of freedom oscillate with different phase angles.

Description : During free vibration, different degrees of freedom oscillate with different phase angles.

Last Answer : False

increases the steady state accuracy. (a) Integrator (b) Differentiator (c) Phase lead compensator (d) Phase lag compensator Ans:A 10.As a result of introduction of negative feedback which of the following will not decrease ? (a) Band width (b) Overall gain (c) Distortion (d) Instability

Description : increases the steady state accuracy. (a) Integrator (b) Differentiator (c) Phase lead compensator (d) Phase lag compensator Ans:A 10.As a result of introduction of negative feedback which of the following will not decrease ? (a) Band width (b) Overall gain (c) Distortion (d) Instability

Last Answer : Ans: A

Differentiate between positive and negative feedback on the basis of . (i) overall phase shift (ii) voltage gain (iii) stability (iv) applications

Description : Differentiate between positive and negative feedback on the basis of . (i) overall phase shift (ii) voltage gain (iii) stability (iv) applications 

Last Answer : Compare positive feedback and negative feedback on the basis of: (i) Gain (ii) Bandwidth (iii) Phase shift (iv) Stability

In the Bode plot of a unity feedback control system, the value of phase of G(jw) at the gain cross -over...

Description : In the Bode plot of a unity feedback control system, the value of phase of G(jw) at the gain cross -over frequency is - 125°.. The phase margin of the system is (a) - 125° (b) - 55° (c) 55° (d) 125°

Last Answer : In the Bode plot of a unity feedback control system, the value of phase of G(jw) at the gain cross -over frequency is - 125°.. The phase margin of the system is 55°

When troubleshooting an amplifier, you measure an output of 30 volts. If the gain of the amplifier is 2, what must the input voltage be for the amplifier to work properly? A. 32 volts B. 30 volts C. 28 volts D. 15 volts

Description : When troubleshooting an amplifier, you measure an output of 30 volts. If the gain of the amplifier is 2, what must the input voltage be for the amplifier to work properly? A. 32 volts B. 30 volts C. 28 volts D. 15 volts

Last Answer : Answer: D

The gain of an ideal amplifier must be

Description : The gain of an ideal amplifier must be

Last Answer : The gain of an ideal amplifier must be infinity

If current gain is required from an rf amplifier, what type of component should be used as an output coupling element?

Description : If current gain is required from an rf amplifier, what type of component should be used as an output coupling element?

Last Answer : A step-down transformer.