AB66 Wien Bridge Oscillator Analog Lab Experiment

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AB66

Wien Bridge Oscillator

Analog Lab

Experiment Board

Ver. 1.0

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Research, Modern manufacturing techniques and continuous improvement in Quality of the products and Services with active participation of employees.

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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

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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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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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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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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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DATASHEET

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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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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.

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Venkateswara nagar, Adyar

CHENNAI – 600025

4.

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202/19, 4 th main street

Ganganagar,

BANGALORE- 560032

5.

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Dadar (East),

MUMBAI –400014

6.

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988, Sadashiv Peth,

Gyan Prabodhini Lane,

PUNE – 411030

7.

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SPS Apartment, 1 st Floor

2, Ahmed Mamoji Street,

Behind Jaiswal Hospital,

Liluah, HOWRAH-711204 W.B.

8.

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Flat No. 205, 2 nd Floor,

Lakshminarayana Apartments

‘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

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Ph : (040) 55465643

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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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