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8/2/2019 SCC Lab Manual
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7.1.1 Title of the Experiment: Measurement of Opamp parameters (I/P Offset current, I/P bias
current, Slew rate, I/P offset Voltage, PSRR, CMRR) & offset nulling.
7.1.2 Objective of the Experiment: To conduct an experiment to verify the Op-amp parameters.
7.1.3 List of Component / Equipments:
Sl. noComponent/
EquipmentsSpecification Quantity
1 Regulated DC 0-30V, 2A 02
2 CRO 80 Vpp/20MHz 01
3 Ammeter 0-500nA 02
4 +12V and -12V
power pack
01
5 Op-Amplifier A-741 01
7.1.4 Experimental setup:
Circuit Diagram
7.1.5 Theoretical background for the experiment/validation of the experiment:
Input bias current is defined as the average of the bias current at the inverting and non
inverting terminals of an OPAMP. Input offset current is the difference between the basecurrent at the inverting and non inverting terminals of an OPAMP. Input impedance is the
resistance seen from either terminals when other terminal is connected to the ground.
Output impedance is the equivalent output resistance seen from either terminal when one
terminal is connected to the ground. Output offset voltage is defined as the amount voltage
when both the inputs are grounded.
7.1.6 Formulae-required:
Input bias current (IBI + IB2/2) Input offset current (IB1-IB2)
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7.1.7 Step by step procedure to carry out experiment:
Electrical connections are made as shown in the circuit diagram. Set Vcc=15V To measure input offset current, bias current and offset voltage, equal voltages are
applied to both the input terminals of an OPAMP.
Respective base current shown by the ammeters are noted down,
Average of these two currents will be the input bias current and difference ofrespective base current gives the input offset current.
For finding output offset voltage ground both the input terminals and note down theoutput voltage.
7.1.8 Table of observation:1. Input bias current = nA2. Input offset current = nA3. Output offset voltage = mV
7.1.9 Specimen calculation: --------- Not Applicable ---------
7.1.10 Nature of graph: --------- Not Applicable ---------
7.1.11 Conclusion of the experiment:
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7.2.1 Title of the Experiment: Inverting amplifier & attenuator, noninverting amplifier&
voltage follower
7.2.2 Objective of the Experiment: To design and test the performance Inverting amplifier &
attenuator, noninverting amplifier and voltage follower.
7.2.3 List of Component / Equipments:
a
7.2.4 Experimental setup:
Inverting Amplifier
Attenuator
Non-inverting Amplifier
Sl.No Components/Equipments Specifications Quantity
1 Regulated DC 0-30V, 2A 02
2 CRO 80 Vpp/20MHz 01
3 Ammeter 0-500nA 02
4 +12V and -12V power pack 01
5 Op-Amplifier A-741 01
6 Resistor 10K watt CFR
1K watt CFR
02
027 Function generator 0-1MHZ 01
8 BNC Probes 02
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Voltage follower
7.2.5 Theoretical background for the experiment/validation of the experiment:
7.2.6 Formulae-required:
Voltage Gain = -Rf/R1. (Inverting amplifier)Let required gain be 10.
Assume R1=1kTherefore Rf=10k.
Voltage gain = (1+Rf/R1), (Non-inverting amplifier)
Let required gain = 11.
Assume R1=1k.Therefore Rf=10k.
7.2.7 Step by step procedure to carry out experiment:
Electrical connections are made as shown in the circuit diagram. Select Input voltage (Vi) of 1 KHz, 0.5Vpp is given from AFO. Note down the output voltage (Vo). And calculate the gain. Repeat all above steps for verifying other circuits.
7.2.8 Table of observation:
Inverting Amplifier
Input Voltage = Vi = Constant
Output Voltage = Vo = Volts
Voltage gain of the amplifier = V0/Vi = . / . = ..
Attenuator
Input Voltage = Vi = Constant
Output Voltage = Vo = Volts
Voltage gain of the amplifier = V0/Vi = . / . = ..
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Non Inverting amplifier
Input Voltage = Vi = Constant
Output Voltage = Vo = Volts
Voltage gain of the amplifier = V0/Vi = . / . = ..
Voltage follower
Input Voltage = Vi = Constant
Output Voltage = Vo = Volts
Voltage gain of the amplifier = V0/Vi = . / . = ..
7.2.9 Specimen calculation: --------- Not Applicable ---------
7.2.10 Nature of graph:
Inverting amplifier
Non-inverting amplifier
Voltage follower
7.2.11 Conclusion of the experiment:
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7.3.1 Title of the Experiment: Adder, substractor, integrator, differentiator
7.3.2 Objective of the Experiment: To study and verify the performance of Op-amp as Adder,
substractor, integrator, differentiator
7.3.3 List of Component / Equipments:
7.3.4
Experimental setup:
Adder circuit
Substractor circuit
Sl.No Components/Equipments Specifications Quantity
1 Regulated DC 0-30V, 2A 02
2 CRO 80 Vpp/20MHz 01
3 Ammeter 0-500nA 02
4 +12V and -12V power pack 01
5 Op-Amplifier A-741 01
6 Resistor
10K watt CFR
1K watt CFR
250 watt CFR
100 watt CFR1.5K watt CFR
02 each
7 Capacitors 0.1F ceramic disc
0.01F ceramic disk
01 each
8 Function generator 0-1MHZ 01
9 BNC Probes 02
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Integrator circuit
Differentiator circuit
7.3.5 Theoretical background for the experiment/validation of the experiment:
For an adder and subtractor : In an adder circuit (here an OPAMP is used in invertingmode. Out put is leaner combination of number of input signals i.e., the output is
proportional to the sum of the inputs. Assuming that the inputs applied are Va, Vb & Vc in
volts then the output voltage is given by Vo= -Rf/R (Va + Vb + Vc). Similarly when the
OPAMP is used as a subtractor , the output is proportional to the difference of the inputs
applied. If Va & Vb are applied as input voltages then the output is given by Vo = - Rf/R
(Va Vb).
In these two equations Rf is the feedback resistor connected between the output terminal
and the inverting input terminal and the resistor R is connected between the input terminal
and the input applied voltage.
For Integrator and Differentiator : In an integrator circuit using an OPAMP the outputvoltage is given by Vo+-/R1Cf Int (Vin dt + C), this equation shows that the amplifier
provides an output voltage proportional to thintegral of the input voltage. For example if
the input is a square wave, the output will be a triangular wave. Similarly for
differentiator the output voltage is given by Vo = - Rf C1 d/dt (Vin). This shows that, the
output is proportional to the time derivative of the input. If the input is a sine wave then the
output will be a cosine wave and the differentiator circuit has high gain at high frequencies.
In the above two equations resistor R1 is connected between the input terminal and the
input signal voltage, where as Rf is connected between the output terminal and the
inverting input terminal. Similarly the capacitor Cf is connected between the output
terminal and the inverting input terminal, where as C1 is connected between the input
terminal and the input signal voltage.
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7.3.6 Formulae-required:
Adder : with Rf = 1 Kohm, R = 1 Kohm,
Gain of the amplifier = - Rf/R = -1.
Then the output voltage Vo is equal to the sum of the i/pt voltages applied.
Subtractor : with Rf = 1 Kohm, R = 1 Kohm,
Gain of the amplifier = - Rf/R = -1.
Then the output voltage Vo is equal to the diff of the i/p voltages applied.
Integrator : Let fo = 1 KHz, Cf = 0.1 Mf
We have fo = 1/ 2 x pi x R1 x Cf,
Then R1 = 1 / 2 x pi x fo x Cf = 1.59 Kohm.
Differentiator : Let fo = 1 KHz, C1 = 0.1 Mf
We have fo = 1/ 2 x pi x Rf x C1,
Then Rf = 1 / 2 x pi x fo x C1 = 1.59 Kohm.
Design of Integrator.Output voltage vo = -(1/R1/Cf) * vin dt +C.0dB frequency fb = 1/(2 * * R1 *Cf).Gain limiting frequency fa = 1/(2 * * Rf * Cf).Let fa = fb/10.
Hence Rf = 10 * R1.
Assume R1 = 100, Cf = 0.1F; Rf = 1k.Hence fa = 1.59kHz & fb = 15.9kHz.
Design of differentiator.
Output voltage = -Rf * C1* d/dt (vin).
0dB frequency fa = 1 / (2 * * Rf * C1).Gain limiting frequency fb = 1 / (2 * * R1 * C1).Select fa equal to highest freq. to be differentiated
Assume C1
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7.3.7 Step by step procedure to carry out experiment:
For an adder and substractor circuit:
Give three DC Voltages as the input to the adder circuit let these voltages be denotedby, Va, Vb and Vc;
Then note down the output voltage either using CRO or a Voltmeter.
Check this output voltage value with the calculated output voltage value. Vary these input voltages and then note down the corresponding output voltage and
then calculate the error using the measured and calculated output voltage values.
Similarly for a subtractor circuit give two DC Voltages as the input signal. Let these be, Va and Vb and note that Va > Vb. Then measure the corresponding output voltage and check the calculated output
voltage and then compare these two values and find out the error.
For an Integrator and Differentiator Circuit:
After connecting the circuit as per the diagram and give a square wave input signal.
Then observe the output wave form on the CRO and this output wave form should bea triangular wave for an intigrator circuit.
Measure the voltage and time period of both the input and output voltages. Similarly for a differentiator circuit give the square wave as an input. And observe the output wave form on the CRO. Measure the voltage time period of both the input and output wave form.
7.3.8 Table of observation:
For AdderVa in V Vb in V Vc in
V
Cald Vo = - Rf/R (Va+Vb+Vc)
in V
Obsd Vo in
V
Error =
Obsd
Cald
For Substractor
Va in V Vb in V Cald Vo = - Rf/R (Va Vb)
in V
Obsd Vo in V Error = Obsd Cald
For Integrator
Input
Voltage Vin
volts
Input time
period in
ms
Input
frequency in
KHZ
Output
voltage Vo in
Volts
Output time
period in ms
Output
frequency in
KHZ
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For Differentiator
Input
Voltage Vin
volts
Input time
period in
ms
Input
frequency in
KHZ
Output
voltage Vo in
Volts
Output time
period in ms
Output
frequency in
KHZ
7.3.9 Specimen calculation: ----- Not applicable -----
7.3.10 Nature of graph:
Integrator
Differentiator
7.3.11 Conclusion of the experiment:
Operational amplifiers can be used for a wide range of applications.They range from
amplification of small signal voltages to mathematical operations such as integration &
differentiation of input voltage signals.
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7.4.1 Title of the Experiment: I to V converter & V to I converter.
7.4.2 Objective of the Experiment: To study and design I to V converter & V to I converter and
verify the performance.
7.4.3 List of Component / Equipments:
Sl. noComponents /
EquipmentsSpecification Quantity
1 Op-Amp A-741 01
2 Resistors 10K watt CFR1K watt CFR
02 each
3 Ammeter 0-50mA 01
4 Power supply 0 30 V, 2A 01
5 ALS power pack +12V and -12V 016 Voltmeter 0-50V 01
7.4.4 Experimental setup:
I to V converter circuit
V-I Converter circuit
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7.4.5 Theoretical background for the experiment/validation of the experiment:
7.4.6 Formulae-required
7.4.7 Step by step procedure to carry out experiment:
For an I to V converter after connecting the circuit the input current is varied in stepsof 1mA and measure the output voltage.
Check this value with the calculated output voltage and find out the error. Similarly for a V to I converter with grounded load, keep the input voltage at
constant value then vary the RL and note down IL and Vo.
Then keep RL constant and vary the input voltage Vin and note down the current IL. The error between the observed and the calculated values should be evaluated.
Same procedure should be followed for a V to I converter with floating load.
7.4.8 Table of observation:
With RL = 500 OhmsVin in Volts I in in mA Calcd Vo in
Volts
Obsd Vo in
Volts
Error = Obsd
Calcd
With Vin = 5 Volts
RL in Ohms Obsd IL in mA Calcd IL=
Vin/R1 in mA
Error = Obsd Calcd
With RL = 500 Ohms
Vin in Volts Obsd IL in mA Calcd IL= Vin/R1 in
mA
Error = Obsd
Calcd
7.4.9 Specimen calculation:
7.4.10 Nature of graph:
Graph for I to V
7.4.11 Conclusion of the experiment:
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7.5.1 Title of the Experiment: Half wave & full wave precision rectifiers
7.5.2 Objective of the Experiment: To study and design of Half wave & full wave precision
rectifiers and verify the performance.
7.5.3 List of Component / Equipments:
Sl. noComponents /
EquipmentsSpecification Quantity
1 Op-Amp A-741 02
2 Resistors 1K watt CFR 05
3 Diode BY-127 02
4 Power supply 0 30 V, 2A 01
5 ALS power pack +12V and -12V 01
6 Voltmeter 0-50V 01
7 AFO 0 1 MHZ 01
8 CRO 01
7.5.4 Experimental setup:
Non inverting precision rectifier
Half wave rectifier
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Full wave precision rectifier
7.5.5 Theoretical background for the experiment/validation of the experiment:
7.5.6 Formulae-required: Not Applicable
7.5.7 Step by step procedure to carry out experiment:
Electrical connections are made as shown in the circuit diagram. The i/p is given from the AFO of required voltage and frequency. The rectified o/p observed on CKO The amplitude of rectified o/p will be equal to half the peak to peak voltage of i/p. Circuit connections are made as per circuit diagram. When diodes D1 & D2 are connected as in 1st circuit the ve half cycle is inverted
&the +ve half cycle remains as it is. So we observe on the CRO that both the cycles
are rectified.
When diodes D1 & D2 are connected as in 2nd circuit the rectified o/p will be alongnegative direction is observed on CRO.
The amplitude of the o/p wave form is noted.7.5.8 Table of observation:
Non Inverting Precision HW-Rectifier
Input
Voltage Vin
volts
Input time
period in
ms
Input
frequency in
KHZ
Output
voltage Vo in
Volts
Output time
period in ms
Output
frequency in
KHZ
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Inverting Precision HW-Rectifier
Input
Voltage Vin
volts
Input time
period in
ms
Input
frequency in
KHZ
Output
voltage Vo in
Volts
Output time
period in ms
Output
frequency in
KHZ
Inverting Precision FW-Rectifier
Input
Voltage Vin
volts
Input time
period in
ms
Input
frequency in
KHZ
Output
voltage Vo in
Volts
Output time
period in ms
Output
frequency in
KHZ
7.5.9 Specimen calculation: . Not Applicable ..
7.5.10 Nature of graph:
Half wave rectifier
Full Wave rectifier
7.5.11 Conclusion of the experiment:
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7.6.1 Title of the Experiment: Design of low pass filters (Butterworth I & II order).
7.6.2 Objective of the Experiment: To design an low pass filters (Butterworth I & II order) and
verify the response.
7.6.3 List of Component / Equipments:
Sl. noComponent/
EquipmentsSpecification Quantity
1 Regulated DC 0-30V, 2A 01
2 CRO 80 Vpp/20MHz 01
3 Crystal 32.768KHz 01
4 BNCs ---- 03
5 BJT 2N3904 01
6 Resistors
27K, 0.25W, CFR
18K, 0.25W, CFR
2.2K, 0.25W, CFR
10K, 0.25W, CFR
01(each)
7 Capacitors
Inductor
12pF(ceramic disc)
0.001micro/25V,
10H
01(each)
7.6.4 Experimental setup:
7.6.5 Theoretical background for the experiment/validation of the experiment:
7.6.6 Formulae-required: ---------Not Applicable---------
7.6.7 Step by step procedure to carry out experiment:
7.6.8 Table of observation:
7.6.9 Specimen calculation: ---------Not Applicable---------
7.6.10 Nature of graph:
7.6.11 Conclusion of the experiment:
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7.7.1 Title of the Experiment: Design of high pass filters (Butterworth I & II order).
7.7.2 Objective of the Experiment: To Design and test the performance of of high pass filters
(Butterworth I & II order).
7.7.3 List of Component / Equipments:
Sl. No Component / Equipments Specification Quantity
1 Diodes OA79,1N4007 02 each
2 Resistor 1k 01
3 AFO 1MHz,20Vp-p 01
4 CRO 20MHz,80Vp-p 01
5 DC Power supply 0 30V, 2A 01
6 BNCs 03
7 Capacitors 0.1uF, 10uF 01,01
7.7.4 Experimental setup:
7.7.5 Theoretical background for the experiment/validation of the experiment:
7.7.6 Formulae-required: ----- Not Applicable -----
7.7.7 Step by step procedure to carry out experiment:
7.7.8 Table of observation:
1.
7.7.9 Specimen calculation: ----- Not Applicable -----
7.7.10 Nature of graph:
7.7.11 Conclusion of the experiment:
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7.8.1 Title of the Experiment: Instrumentation amplifier- Design for Different gains
7.8.2 Objective of the Experiment: To design and test the performance of Instrumentation
amplifier- Design for Different gains.
7.8.3 List of Component / Equipments:
Sl. No Component / Equipments Specification Quantity
1
2
3
4
5
6
7.8.4 Experimental setup:
Instrumentation Amplifier
7.8.5 Theoretical background for the experiment/validation of the experiment:
7.8.6 Formulae-required: ----- Not Applicable -----
7.8.7 Step by step procedure to carry out experiment:
Electrical connections are made as shown in the circuit diagram. The function generator (AFO) is kept at 1 kHz frequency and Vin at 3Vp. The input and output waveforms for both circuits are noted/plotted down.
7.8.8 Table of observation:
7.8.9 Specimen calculation: ----- Not Applicable -----
7.8.10 Nature of graph:
7.8.11 Conclusion of the experiment:
After conducting the experiment we Conclude that the input ac signal is clamped to the
desired DC level by providing the DC bias to the clamping circuit.
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7.9.1 Title of the Experiment: RC phase shift and Wein bridge Oscillators.
7.9.2 Objective of the Experiment: To design and study the performance of RC phase shift and
Wein bridge Oscillators
7.9.3 List of Component / Equipments:
Sl. noComponents /
EquipmentsSpecification Quantity
1 ALS power supply +12V and -12V, 2A 01
2 Resistors Calculated values to be place 03
3 Capacitors 0.1F 03
4 Power supply 0 30 V, 2A 01
5 BNC 01
6 CRO 20 MHz/80Vpp 01
7 Op-amp A-741 01
7.9.4 Experimental setup:
PC phase shift oscillator
Wein bridge oscillator
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7.9.5 Theoretical background for the experiment/validation of the experiment:
A phase-shift oscillator is a simple sine wave electronic oscillator. It contains an inverting
amplifier, and a feedback filter which 'shifts' the phase by 180 degrees at the oscillation
frequency.
The filter must be designed so that at frequencies above and below the oscillation frequency the
signal is shifted by either more or less than 180 degrees. This results in constructive
superposition for signals at the oscillation frequencies, and destructive superposition for all other
frequencies.
The most common way of achieving this kind of filter is using three cascaded resistor-capacitor
filters, which produce no phase shift at one end of the frequency scale, and a phase shift of 270
degrees at the other end. At the oscillation frequency each filter produces a phase shift of 60
degrees and the whole filter circuit produces a phase shift of 180 degrees.
One of the simplest implementations for this type of oscillator uses an operational amplifier (op-
amp), three capacitors and four resistors, as shown in the diagram.
The mathematics for calculating the oscillation frequency and oscillation criterion for this circuit
are surprisingly complex, due to each R-C stage loading the previous ones. The calculations are
greatly simplified by setting all the resistors (except the negative feedbackresistor) and all the
capacitors to the same values. In the diagram, if R1 = R2 = R3 =R, and C1 = C2 = C3 = C, then
and the oscillation criterion is:
A Wien bridge oscillator is a type of electronic oscillator that generates sine waves without
having any input source. It can output a large range of frequencies. The bridge comprises four
resistors and two capacitors. The circuit is based on a network originally developed by Max Wienin 1891. At that time, Wien did not have a means of developing electronic gain so a workable
oscillator could not be realized. The modern circuit is derived from William Hewlett's 1939
Stanford University master's degree thesis. Hewlett, along with David Packard co-founded
Hewlett-Packard. Their first product was the HP 200A, a precision sine wave oscillator based on
the Wien bridge. The 200A is a classic instrument known for its low distortion.
The frequency of oscillation is given by:
http://en.wikipedia.org/wiki/Sine_wavehttp://en.wikipedia.org/wiki/Electronic_oscillatorhttp://en.wikipedia.org/wiki/Feedbackhttp://en.wikipedia.org/wiki/Phase_%28waves%29http://en.wikipedia.org/wiki/Electronic_filterhttp://en.wikipedia.org/wiki/Operational_amplifierhttp://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Resistorhttp://en.wikipedia.org/wiki/Negative_feedbackhttp://en.wikipedia.org/wiki/Electronic_oscillatorhttp://en.wikipedia.org/wiki/Sine_wavehttp://en.wikipedia.org/wiki/Resistorhttp://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Max_Wienhttp://en.wikipedia.org/wiki/Gainhttp://en.wikipedia.org/wiki/William_Hewletthttp://en.wikipedia.org/wiki/Stanford_Universityhttp://en.wikipedia.org/wiki/David_Packardhttp://en.wikipedia.org/wiki/Hewlett-Packardhttp://en.wikipedia.org/wiki/Distortionhttp://en.wikipedia.org/wiki/Distortionhttp://en.wikipedia.org/wiki/Hewlett-Packardhttp://en.wikipedia.org/wiki/David_Packardhttp://en.wikipedia.org/wiki/Stanford_Universityhttp://en.wikipedia.org/wiki/William_Hewletthttp://en.wikipedia.org/wiki/Gainhttp://en.wikipedia.org/wiki/Max_Wienhttp://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Resistorhttp://en.wikipedia.org/wiki/Sine_wavehttp://en.wikipedia.org/wiki/Electronic_oscillatorhttp://en.wikipedia.org/wiki/Negative_feedbackhttp://en.wikipedia.org/wiki/Resistorhttp://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Operational_amplifierhttp://en.wikipedia.org/wiki/Electronic_filterhttp://en.wikipedia.org/wiki/Phase_%28waves%29http://en.wikipedia.org/wiki/Feedbackhttp://en.wikipedia.org/wiki/Electronic_oscillatorhttp://en.wikipedia.org/wiki/Sine_wave8/2/2019 SCC Lab Manual
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7.9.6 Formulae-required
3.
7.9.7 Step by step procedure to carry out experiment:
Electrical connections are made as per circuit diagram. The designed values of resistors and capacitors are added to the circuit. The output waveform is observed on CRO. Note down the practical values such as output magnitude and frequency. Calculate the theoretical output frequency. And finally calculate the deviations.
7.9.8 Table of observation:
RC Phase shift Oscillator
Output Voltage
in volts
Output wave
time T in ms
Practical requency
in KHz= 1/T
Theoratical
Frequency
Error
Wein bridge Oscillator
Output Voltage
in volts
Output wave
time T in ms
Practical requency
in KHz= 1/T
Theoratical
Frequency
Error
7.9.9 Specimen calculation:
7.9.10 Nature of graph:
7.9.11 Conclusion of the experiment:
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7.10.1 Title of the Experiment: ZCD, Positive voltage level & Negative voltage level detectors.
7.10.2 Objective of the Experiment: To design and study the performance of ZCD, Positive
voltage level & Negative voltage level detectors.
7.10.3 List of Component / Equipments:
7.10.4 Experimental setup:
7.10.5 Theoretical background for the experiment/validation of the experiment:
7.10.6 Formulae-required
7.10.7 Step by step procedure to carry out experiment:
7.10.8 Table of observation:
Without Filter:
7.10.9 Specimen calculation:
7.10.10 Nature of graph
7.10.11 Conclusion of the experiment:
Sl.No Item Specification Quantity
1. Diode BY127 04
2. Resistors 2.2k,1k, 4.7k 01 each
3. Capacitors 0.1uF10F, 4.7F, 47F 01 each
4. Step down transformer 6-0-6V, 9-0-9V 01 each
5. CRO 20 MHz,80Vp-p 01
6. DMM 500V/10A/200mA 03
7. DRB 1-1Mohm 01
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7.11.1 Title of the Experiment: Schmitt trigger- Design for different hystersis.
7.11.2 Objective of the Experiment: Design and Testing of Schmitt trigger for a noise margin
+/-12V and dead band of 6V
7.11.3 List of Component / Equipments:
7.11.4 Experimental setup:
7.11.5 Theoretical background for the experiment/validation of the experiment:
Schmitt trigger converts on irregular shaped waveform to a square wave or pulse. The i/p
voltage Vin triggers the o/p every time it exceeds certain voltage levels called the
upperthreshold voltage VUT and lower threshold voltage VLT.
When Vo = +Vsat the voltage across R1 is called the upper threshold voltage VUT
VUT=21
1
RR
R
+
(+Vsat)
The i/p voltage Vin must be slightly more positive than V UT in order to cause the o/p Vo
to switch from +Vsat to Vsat .
When Vo=-Vsat
The lower threshold voltage Vlt is given as VLT=21
1
RR
R
+(-Vsat)
Sl.No Item Specification Quantity1. Resistors 300K watt CFR
10K watt CFR
01 each
2. CRO 20 MHz,80Vp-p 01
3. DMM 500V/10A/200mA 03
4. DC Power supply 0 30 V, 2A 01
5. Op-amp A-741 01
6. AFO 0-1MHZ 01
7 BNC 02
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Vin must be slightly more negative than VLT in order to cause Vo to switch from Vsat to
+Vsat.
Thus if threshold voltage VUT & VLT are made larger than i/p noise margin the positive
feedback will eliminate the false o/p transaction.
7.11.6 Formulae-required
1. VUT=21
1
RR
R
+(+Vsat)
2. VLT=21
1
RR
R
+(-Vsat)
3. Design Calculation
Given data: Noise margin = 2V, dead band = 6 V, +Vsat= +12V, -Vsat= - 12V
7.11.7 Step by step procedure to carry out experiment:
Connections are made as per circuit diagram. The i/p is given in such a way that the o/p switches between +Vsat and Vsat. From the o/p waveform and the i/p waveform the dead band is calculated. Feeding i/p to channel A and o/p to channel B and adjusting CRO to x vin A mode the
hysteresis width is measured.
7.11.8 Table of observation:
Input
Voltage Vin
volts
Noise
margin
Dead band
voltage
+Ve Sat
voltage
-ve Saturation
Voltage
Output
frequency in
KHZ
7.11.9 Specimen calculation:
7.11.10 Nature of graph:
7.11.11 Conclusion of the experiment:
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7.12.1 Title of the Experiment: Design of Astable and Monostable Multivibrator using 555
timer.
7.12.2 Objective of the Experiment: To design and study the performance of Astable and
Monostable Multivibrator using 555 timer.
7.12.3 List of Component / Equipments:
7.12.4 Experimental setup:
555 timer as astable multivibrator:
555 Timer as Monostable multivibrator:
Sl.No Item Specification Quantity
1. Regulated Power supply 0-30V 1
2. Resistors 1K watt CFR
500 watt CFR01 each
3. Capacitors 0.1F 01 each
4. CRO 20 MHz,80Vp-p 01
5. BNC 01
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7.12.5 Theoretical background for the experiment/validation of the experiment:
Astable Multivibrator:
Circuit diagram shows how a 555 timer IC is configured to function as an astable
multivibrator. An astable multivibrator is a timing circuit whose 'low' and 'high' states
are both unstable. As such, the output of an astable multivibrator toggles between 'low'
and 'high' continuously, in effect generating a train of pulses. This circuit is therefore
also known as a 'pulse generator' circuit.
In this circuit, capacitor C1 charges through R1 and R2, eventually building up enough
voltage to trigger an internal comparator to toggle the output flip-flop. Once toggled,
the flip-flop discharges C1 through R2 into pin 7, which is the discharge pin. When
C1's voltage becomes low enough, another internal comparator is triggered to toggle
the output flip-flop. This once again allows C1 to charge up through R1 and R2 and the
cycle starts all over again.
C1's charge-up time t1 is given by: t1 = 0.693(R1+R2)C1. C1's discharge time t2 is
given by: t2 = 0.693(R2)C1. Thus, the total period of one cycle is t1+t2 = 0.693
C1(R1+2R2). The frequency f of the output wave is the reciprocal of this period, and istherefore given by: f = 1.44/(C1(R1+2R2)), wherein f is in Hz if R1 and R2 are in
megaohms and C1 is in microfarads.
Monostable Multivibrator:
This circuit diagram shows how a 555 timer IC is configured to function as a basic
monostable multivibrator. A monostable multivibrator is a timing circuit that changes
state once triggered, but returns to its original state after a certain time delay. It got its
name from the fact that only one of its output states is stable. It is also known as a 'one-
shot'.
In this circuit, a negative pulse applied at pin 2 triggers an internal flip-flop that turns
off pin 7's discharge transistor, allowing C1 to charge up through R1. At the same time,
the flip-flop brings the output (pin 3) level to 'high'. When capacitor C1 as charged up
to about 2/3 Vcc, the flip-flop is triggered once again, this time making the pin 3 output
'low' and turning on pin 7's discharge transistor, which discharges C1 to ground. This
circuit, in effect, produces a pulse at pin 3 whose width t is just the product of R1 and
C1, i.e., t=1.1 R1C1.
The reset pin, which may be used to reset the timing cycle by pulling it momentarily
low, should be tied to the Vcc if it will not be used.
7.12.6 Formulae-required
1. T1 = 0.693 (Ra + Rb) * Ct charge time of Ct.
2. T2 = 0.693 (Rb * Ct) discharge time of Ct.
3. T = T1 + T 2 total period in seconds.
4. F = 1 / T = 1.44 / ((Ra + (2 * Rb)) * Ct) Frequency in Hertz.
5. D = T 2 / T duty cycle, multiply by 100 to get %..
6. % Duty Cycle = tc/t x 100
= 100
2
X
RBRA
RBRA
+
+
7. T = 1.1RC
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7.12.7 Step by step procedure to carry out experiment:
Astable Multivibrator:
Design a astable multi for a pulse of 1.386ms. Set duty cycle to 75%. Verify the values of RA=1k, RB=0.5k. Connect the circuit as shown in Figure. Measure and capture the waveforms of the input, output and the voltage across thecapacitor. Measure the time period and duty cycle of the output and compare with the theoretical
values.
Monostable Multivibrator:
Design a monostable multi for a pulse of 1.1 ms. Connect the circuit as shown in figure. Using a wire connect trigger input to ground momentarily to trigger the circuit. Since
T is high enough,
You should be able to see the single pulse on the scope screen connected to theoutput. Try a few times until you see the whole pulse and measure the width.
Compare this width (period) with the time period you calculated. Alternatively disconnect the output from the scope and connect to a series circuit
consisting of an LED and a 150 ohm resistor.
Using a wire connect trigger input to ground momentarily to trigger the circuit. Youshould observe LED blink for a short period of time set by the period. Show your
results to your instructor/ lab TA.
7.12.8 Table of observation:
Astable Multivibrator:1. TC = .. Sec2. TD = .. Sec3. T= TC + TD = sec4. Frequency = F = 1/T = .. HZ
Monostable Multivibrator:
1. TON = .. Sec2. TOFF = sec3. T = TON + TOFF = .. Sec4.
F = 1 / T = HZ.
7.12.9 Specimen calculation:
1.Astable multivibrator:
2. Monostable multivibrator:
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7.12.10 Nature of graph
Astable Multivibrator:
Monostable Multivibrator:
7.12.11 Conclusion of the experiment: After conducting the experiment we conclude that,
astable multivibrator is a free running oscillator. And monostable multivibrator has one
stable state, it changes its state when trigger pulse is applied. After some time delay its
output comes back to original state.