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WorksheetsOSCILLATORS
Total questions: 60
Worksheet time: 33mins
What are the two components in an oscillator
amplifier and rectifier
inverter and amplifier
amplifier and feedback
inverter and feedback
Name two RC oscillators
Name two LC oscillators
Which crystal is used in crystal oscillators
Write two conditions of barkhausen criteria
What happens to the voltage gain when negative voltage feedback is applied to an amplifier?
Is increased
Is reduced
Remains the same
None of the above
Emitter follower is a _________ circuit
Voltage feedback
Current feedback
Both voltage and current feedback
Current Series feedback
Negative feedback is employed in _______
Oscillator
Amplifier
Rectifier
Converter
What is the ratio of the input impedance with series feedback to that without feedback?
1 + βA
Β
βA
1
How many combinations of feedback connections are available?
1
2
3
4
An oscillator converts ______
a.c. power into d.c. power
d.c. power into a.c. power
Mechanical power into a.c. power
None of the options are correct
An oscillator differs from an amplifier because it
Has more gain
Requires no input signal
Requires no d.c. supply
Always has the same input
What is the condition for oscillation?
A phase shift around the feedback loop of 180°
A phase shift around the feedback loop of 0°
A gain around the feedback loop of one-third
A gain around the feedback loop of less than 1
The gain of an amplifier without feedback is 100 db. If a negative feedback of 3 db is applied, the gain of the amplifier will become
3 db
5 db
103 db
97 db
The piezoelectric effect in a crystal is____________
A voltage developed because of mechanical stress
A change in resistance because of temperature
A change in frequency because of temperature
A change in frequency
In an RC phase shift oscillator R=200KΩ and C=100pF.Find the frequency of oscillator.
3.24KHz
2.3KHz
4.24KHz
5.1KHz
Identify the high frequency oscillators.
Hartley Oscillator
Colpitts Oscillator
Both Hartley and Colpitts Oscillator
Crystal oscillator
Which of the following oscillator types provides extremely stable output frequency.
Colpitt's oscillator
Wein bridge oscillator
Crystal oscillator
Hartley oscillator
How many RC sections are used in a phase shift oscillator?
1
2
4
3
Hartley oscillator is commonly used in _________
Radio receivers
Radio transmitters
TV receivers
Frequency receiver
An oscillator produces……………. oscillations
Damped
Undamped
Modulated
None of the above
An oscillator employs ……………… feedback
Positive
Negative
Neither positive nor negative
Data insufficient
One condition for oscillation is ………….
A phase shift around the feedback loop of 180
A gain around the feedback loop of one-third
A phase shift around the feedback loop of 0
A gain around the feedback loop of less than 1
A second condition for oscillations is ……………….
A gain of 1 around the feedback loop
No gain around the feedback loop
The attention of the feedback circuit must be one-third
The feedback circuit must be capacitive
Which among the below-mentioned oscillators does not adopt any kind of feedback mechanism?
Wein bridge oscillator
UJT relaxation oscillator
Phase-shift oscillator
All of the above
Which of the following is the main advantage of using oscillators?
Suitability for low voltages
High output voltage
Constant frequency of oscillations
High frequency
In oscillator circuits the energy feedback to its input terminal from output is
Always in phase with the input signal
2700 out of phase with the input signal
1800 out of phase with the input signal
900 out of phase with the input signal
Oscillations occur with
Positive feedback having unity loop
Positive feedback having unity loop gain
Negative feedback having unity loop gain
None of the above
What is an oscillator
To produces a sinusoidal waveform on its output
To produces a non sinusoidal waveform on its output
To produces a periodic waveform on its output
To produces a periodic waveform on its input
Name the condition for an Oscillator
Ohm's law
Barkhausen Criteria
Zener Breakdown
None
Determine the amplitude from the graph. What is the amplitude?
5 cm
6 cm
7.5 cm
8 cm
A single RC network provides ......................phase shift
180 degree
60 degree
90 degree
Identify the LC OScillators?
Hartley Oscillator
Phase Shift OScillator
Clapps Oscillator
Amstrong Oscillator
What are the applications of LC Oscillator?
Sine wave generator
Radio Recievers
Radio Transmitter
Television systems
Colpitts oscillator consists of _____ capacitor and _______ inductor
one, one
one, two
two, two
two, one
Hartley oscillator consists of _____ capacitor and _______ inductor
two, two
one, two
one, one
two, one
What is the significant advantage of Clapps Oscillator?
Improves the input impedence
Improves the output impedence
Improves CMRR
Improves the frequency stability
Crystals in Oscillators are made using?
Gold
Quartz
Silver
Mercury
Quartz crystal works on the principle of?
Piezo electric Effect
Piezo resistive Effect
Piezo capacitive Effect
Piezo inductive Effect
In a Hartley oscillator the condition for sustained oscillation is β=L1/L2. If there exists mutual inductance M between coils L1 & L2 , then the condition will get modified as β =
M L1 / L2
L1 / M L2
L1 + M / L2 + M
L1- M / L2 - M
In the Colpitts oscillator, the frequency is determined by _______ .
resistance only
inductance only
capacitance only
both inductance and a capacitance
The Colpitt’s oscillator provides better performance than Hartley oscillator in _________.
all frequency region
mid frequency region
high frequency region
low frequency region
In an RC phase shift oscillator if R1 = R2 = R3= 200 KΩ and C1 = C2 = C3 =100 pF, then frequency of oscillation is ______________.
3.0 KHz
3.24 MHz
3.24 KHz
2.43 KHz
A crystal has L=0.33 H, Cs= 0.065 pF, Cp=1.0 pF and R=5.5 KΩ, then parallel resonant frequency is exceeds the series resonant frequency by_________________.
3.2 %
3.1 %
2.5 %
1.3 %
The main advantage of crystal oscillator is that its output is ____________.
a constant frequency
dc
50 Hz to 60 Hz
variable frequency
A quartz crystal has L=0.08 H, C1= 0.08 pF, C2=1.0 pF and R=5000Ω, the parallel resonating frequency is ____________.
629 KHZ
654 KHz
654 MHz
629 MHz
A quartz crystal has L=0.5 H, Cs= 0.06 pF, Cp=1.0 pF and R=5 KΩ, the series resonance frequency & quality factor are _______________respectively.
919 KHz, 577
946 KHz, 594
946 MHz, 577
919 MHz, 594
The essential condition for sustained oscillations are________.
|Aβ|= 1, Aβ=0°
|Aβ|˂ 1, Aβ=0°
|Aβ| ˃ 1, Aβ=0°
|Aβ| ˃ 1, Aβ=0°
An R-C Phase shift oscillator will not produce any oscillations until & unless the voltage gain of internal amplifier is________.
unity
less than unity
around 3
more than 29
In Wien bridge oscillator using common emitter amplifier, the phase shift produced by the feedback network is _____________.
0°
90°
180°
360°
In a wien bridge oscillator with R=5 KΩ and C=0.01 µF, the frequency of oscillation will be__________________.
7.8 KHz
3.2 KHz
2.5 KHz
780 Hz
Consider the following statement regarding an R-C phase shift oscillator.
1. The amplifier gain is positive.
2. The amplifier gain is negative
3. The phase shift introduce by the feedback network
is 180°
4. The phase shift introduce by the feedback network
is 360°
Of these statements
1 & 3 are correct
2 & 3 are correct
2 & 4 are correct
1& 4 are correct
For generating a 1 MHz signal, the most suitable oscillator circuit is_______________.
Colpitts oscillator
phase shift oscillator
Wien bridge oscillator
blocking oscillator
In an R-C phase shift oscillator, the minimum number of R-C network to be connected in cascade will be________.
one
two
three
four
In a colpitts oscillator, the values of the inductor & capacitors in the tank circuit are:
L= 40 mH, C1=100 pF & C2=500 pF and it provide output voltage of 10 V, then the feedback voltage is___________.
5 V
2 V
50 V
10 V
In colpitts oscillator, C1= 0.2 µF and C2 = 0.02 µF and provides frequency of oscillation is 10KHz. The voltage gain required to produce oscillation is__________.
0.1
10
100
1000
In Hartley oscillator, the inductor L2=0.4 mH & C=0.004 µF provides the frequency of oscillator is 120 KHz. The value of inductor L1 is _____________.
0.04 mH
0.04 µH
0.4 H
0.4 mH
The Hartley oscillator uses C = 500 pF and tapped inductors L1 = 36 µH & L2=12 µH. The feedback factors (β) will be_______________.
0.33
3
24
48
The frequency of oscillaton of R-C phase shift oscillator for R=10 KΩ, C=0.01 µF & Rc = 2.2KΩ is ___________.
550 KHz
470 Hz
370 KHz
607 Hz
f the crystal frequency changes with temperature, we say that crystal has ………….. temperature coefficient
Positive
Zero
Negative
None of the above
