AB66
Wien Bridge Oscillator
Analog Lab
Experiment Board
Ver. 1.0
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94-101, Electronic Complex, Pardesipura INDORE -452010, India.
Tel.
: 91-731-2570301 Fax: 91-731-2555643
Email : info@scientech.bz Web : www.scientech.bz

AB66
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AB66
Wien Bridge Oscillator
AB66
TABLE OF CONTENTS
1.
Introduction
2.
Theory
3.
Experiment
To study Wien Bridge oscillator and effect on
Output frequency with variation in RC combination.
4.
Datasheet
5.
Warranty
6.
List of Service Centers
7.
List of Accessories with AB66
10
11
7
9
12
4
6
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INTRODUCTION
AB66 is a compact, ready to use Wien Bridge Oscillator experiment board. This is useful for students to understand functionality of Wien
Bridge oscillator and the effect of RC combination on the Output frequency.
It can be used as stand alone unit with external DC power supply or can be used with SCIENTECH Analog Lab ST2612 which has built in DC power supply, AC power supply, function generator, modulation generator, continuity tester, toggle switches and potentiometer.
AB11
AB14
AB15
AB16
AB17
AB18
AB19
AB20
AB21
AB22
AB23
AB25
AB01
AB02
AB03
AB04
AB05
AB06
AB07
AB08
AB09
AB10
List of Boards :
Model
AB28
AB29
AB30
AB31
AB32
AB33
Name
Diode characteristics (Si, Zener, LED)
Transistor characteristics (CB NPN)
Transistor characteristics (CB PNP)
Transistor characteristics (CE NPN)
Transistor characteristics (CE PNP)
Transistor characteristics (CC NPN)
Transistor characteristics (CC PNP)
FET characteristics
Rectifier Circuits
Wheatstone Bridge
Maxwell’s Bridge
Darlington Pair
Common Emitter Amplifier
Common Collector Amplifier
Common Base Amplifier
Cascode Amplifier
RC-Coupled Amplifier
Direct Coupled Amplifier
Class a Amplifier
Class B Amplifier (push pull emitter follower)
Class C Tuned Amplifier
Phase Locked Loop (FM Demodulator & Frequency
Divider / Multiplier)
Multivibrator ( Mono stable / Astable)
F-V and V-F Converter
V-I and I-V Converter
Zener Voltage Regulator
Transistor Series Voltage Regulator
Transistor Shunt Voltage Regulator
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AB66
AB41
AB42
AB43
AB44
AB45
AB51
AB52
AB53
AB54
AB56
AB65
AB67
AB68
AB80
AB81
AB82
AB83
AB84
AB85
AB88
AB89
AB90
AB91
AB92
AB93
AB96
AB97
AB101
AB102
AB106
Differential Amplifier (Transistorized)
Operational Amplifier (Inverting / Non-inverting /
Differentiator)
Operational Amplifier (Adder/Scalar)
Operational Amplifier (Integrator/ Differentiator)
Schmitt Trigger and Comparator
Active filters (Low Pass and High Pass)
Active Band Pass Filter
Notch Filter
Tschebyscheff Filter
Fiber Optic Analog Link
Phase Shift Oscillator
Colpitt Oscillator
Hartley Oscillator
RLC Series and RLC Parallel Resonance
Kirchoff’s Laws (Kirchhoff’s Current Law & Kirchhoff’s
Voltage Law)
Thevenin’s and Maximum power Transfer Theorem
Reciprocity and Superposition Theorem
Tellegen’s Theorem
Norton’s theorem
Diode Clipper
Diode Clampers
Two port network parameter
Optical Transducer (Photovoltaic cell)
Optical Transducer (Photoconductive cell/LDR)
Optical Transducer (PhotoTransistor)
Temperature Transducer (RTD & IC335)
Temperature Transducer (Thermocouple)
DSB Modulator and Demodulator
SSB Modulator and Demodulator
FM Modulator and Demodulator
………… and many more
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THEORY
Oscillators are circuits that produce periodic waveforms without input other than perhaps a trigger. They generally use some form of active device, lamp, or crystal, surrounded by passive devices such as resistors, capacitors, and inductors, to generate the output.
There are two main classes of oscillator: relaxation and sinusoidal.
Relaxation oscillators generate the triangular, sawtooth and other non sinusoidal waveforms. Sinusoidal oscillators consist of amplifiers with external components used to generate oscillation, or crystals that internally generate the oscillation. The focus here is on sine wave oscillators, created using operational amplifiers op amps. Sine wave oscillators are used as references or test waveforms by many circuits.
An oscillator is a type of feedback amplifier in which part of the output is fed back to the input via a feedback circuit. If the signal fed back is of proper magnitude and phase, the circuit produces alternating currents or voltages. Two requirements for oscillation are :
1.
The magnitude of the loop gain A
V
B must be at least 1.
2.
The total phase shift of the loop gain AvB must be equal to 0° or
360°. If the amplifier causes a phase shift of 180°, the feedback circuit must provide an additional phase shift of 180° so that the total phase shift around the loop is 360°.
Wien Bridge Oscillator :
The Wien Bridge is one of the simplest and best known oscillators and is used extensively in circuits for audio applications. Figure 1 shows the basic
Wien Bridge circuit configuration. On the positive side, this circuit has only a few components and good frequency stability.
Because of its simplicity and stability, it is the most commonly used audiofrequency oscillator. In the Fig shown the Wien Bridge circuit is connected between the amplifier input terminals and the output terminal. The bridge has a series RC network in one arm and a parallel RC network in the adjoining arm. In the remaining two arms of the bridge, resistor R1 and Rf are connected.
The phase angle criterion for oscillation is that the total phase shift around the circuit mudt be 0°. This condition occurs only when the bridge is balanced, that is at resonance. The frequency of oscillation Fo is exactly the resonant frequency of the balanced Wien Bridge and is given by
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AB66
Fo = 1/2 π RC = 0.159 / RC
Assuming that the resistors are equal in the value, and the capacitors are equal in the value in the reactive leg of the Wien Bridge. At this frequency the gain required for sustained oscillation is given by
That is,
Or
Av = 1/B = 3
1+ R f
/ R
1
= 3
R f
= 2R
1
Wien-Bridge Circuit Schematic
Fig. 1
EXPERIMENT
Objective :
To study Wien Bridge Oscillator and effect on output frequency with variation in RC combination.
Apparatus required :
1.
Analog board of AB66.
2.
DC power supplies -12V, +12V from external source or ST2612
Analog Lab .
3.
2 mm patch cords.
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AB66
Circuit diagram :
Circuit used to study Wien Bridge Oscillator is shown in Fig 2.
Fig. 2
Procedure :
To study Wien Bridge oscillator proceed as follows :
1.
Connect +12V,-12V dc power supplies at their indicated position from external source or ST2612 Analog Lab .
2.
3.
Connect a 2mm patch cord between test point I and H.
Switch ON the power supply.
4.
Vary R f
Pot to make gain (R f
/ R l
) greater than 2.
5.
Record the value of output frequency at test point G.
6.
Compare measured frequency with the theoretically calculated value.
7.
Vary gain Pot of 470K to adjust gain of the amplifier in case of clipped waveform.
8.
Switch OFF the power supply.
9.
Connect a 2 mm patch cord between test points A and B, D and E.
10.
Repeat the above steps from step 3 to 8.
11.
Switch OFF the power supply
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AB66
12.
Connect a 2 mm patch cord between test points B and C, E and F.
13.
Repeat the above steps from step 3 to 8.
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AB66
DATASHEET
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AB66
WARRANTY
1) We guarantee the instrument against all manufacturing defects during
24 months from the date of sale by us or through our dealers.
2) The guarantee covers manufacturing defects in respect of indigenous components and material limited to the warranty extended to us by the original manufacturer, and defect will be rectified as far as lies within our control.
3) The guarantee will become INVALID.
a) If the instrument is not operated as per instruction given in the instruction manual. b) If the agreed payment terms and other conditions of sale are not followed.
c) If the customer resells the instrument to another party.
d) Provided no attempt have been made to service and modify the instrument.
4) The non-working of the instrument is to be communicated to us immediately giving full details of the complaints and defects noticed specifically mentioning the type and sr. no. of the instrument, date of purchase etc.
5) The repair work will be carried out, provided the instrument is dispatched securely packed and insured with the railways. To and fro charges will be to the account of the customer.
DESPATCH PROCEDURE FOR SERVICE
Should it become necessary to send back the instrument to factory please observe the following procedure:
1) Before dispatching the instrument please write to us giving fully details of the fault noticed.
2) After receipt of your letter our repairs dept. will advise you whether it is necessary to send the instrument back to us for repairs or the adjustment is possible in your premises.
Dispatch the instrument (only on the receipt of our advice) securely packed in original packing duly insured and freight paid along with accessories and a copy of the details noticed to us at our factory address.
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AB66
LIST OF SERVICE CENTERS
1.
Scientech Technologies Pvt. Ltd.
90, Electronic Complex
Pardesipura,
INDORE – 452010
2.
Scientech Technologies Pvt. Ltd.
First Floor, C-19,
F.I.E., Patparganj Industrial Area,
DELHI – 110092
3.
Scientech Technologies Pvt. Ltd.
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Venkateswara nagar, Adyar
CHENNAI – 600025
4.
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202/19, 4 th main street
Ganganagar,
BANGALORE- 560032
5.
Scientech Technologies Pvt. Ltd.
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Dadar (East),
MUMBAI –400014
6.
Scientech Technologies Pvt. Ltd.
988, Sadashiv Peth,
Gyan Prabodhini Lane,
PUNE – 411030
7.
Scientech Technologies Pvt. Ltd
SPS Apartment, 1 st Floor
2, Ahmed Mamoji Street,
Behind Jaiswal Hospital,
Liluah, HOWRAH-711204 W.B.
8.
Scientech Technologies Pvt. Ltd
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‘C’ wing, Street No. 17,
Himaytnagar,
HYDERABAD- 500029
Ph : (0731) 2570301
Email : info@scientech.bz
Ph : (011) 22157370, 22157371
Fax : (011) 22157369
Email : ndel@scientech.bz
Ph : (044) 42187548, 42187549
Fax : (044) 42187549
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Ph : +913355266800
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Ph : (040) 55465643
Email : hyd@scientech.bz
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AB66
LIST OF ACCESSORIES
1.
2mm Patch cord (red) .........................................................2 Nos.
2.
2mm Patch cord (black) ......................................................2 Nos.
3.
2mm Patch cord (blue) ........................................................3 Nos.
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