AB59
Maxwell’s Inductance Bridge
Analog Lab
Experiment Board
Ver. 1.0
QUALITY POLICY
To be a Global Provider of Innovative and Affordable
Electronic Equipments for Technology Training by
enhancing Customer Satisfaction based on
Research, Modern manufacturing techniques and
continuous improvement in Quality of the products
and Services with active participation of employees.
An ISO 9001: 2000 company
94-101, Electronic Complex, Pardesipura INDORE-452010, India.
Tel.: 91-731-2570301 Fax: 91-731-2555643
Email: info@scientech.bz Web: www.scientech.bz
AB59
Scientech Technologies Pvt. Ltd.
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AB59
Maxwell’s Inductance Bridge
AB59
TABLE OF CONTENTS
1.Introduction
4
2. Theory
6
3.Maxwell’s Inductance Bridge
8
4.Experiment
To measure the value of unknown inductance with the
help of Maxwell’s Inductance Bridge
9
5.Observation table
11
6.Datasheet
12
7.Warranty
14
8.List of Service Centers
15
9.List of Accessories with AB59
16
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AB59
INTRODUCTION
AB59 is a compact, ready to use Maxwell’s Inductance Bridge experiment
board. This bridge is the simplest way to determine the
value of unknown inductance by comparing the branch
impedance of the bridge. 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 switch, and
potentiometer.
List of Boards :
Model
Name
AB01
AB02
AB03
AB04
AB05
AB06
AB07
AB08
AB09
AB10
AB11
AB12
AB13
AB14
AB15
AB16
AB17
AB18
AB19
AB20
AB21
AB22
AB23
AB25
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
De Sauty’s Bridge
Schering 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)
AB28
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AB59
AB29
AB30
AB31
AB32
AB33
AB35
AB39
AB41
AB42
AB43
AB44
AB45
AB49
AB51
AB52
AB54
AB56
AB57
AB58
AB64
AB66
AB67
AB68
AB80
AB82
AB83
AB84
AB85
AB88
AB89
AB90
AB91
AB92
AB93
AB96
AB97
AB101
AB102
AB106
F-V and V-F Converter
V-I and I-V Converter
Zener Voltage Regulator
Transistor Series Voltage Regulator
Transistor Shunt Voltage Regulator
DC Ammeter
Instrumentation Amplifier
Differential Amplifier (Transistorized)
Operational Amplifier (Inverting / Non-inverting
Differentiator)
Operational Amplifier (Adder/Scalar)
Operational Amplifier (Integrator/ Differentiator)
Schmitt Trigger and Comparator
K Derived Filter
Active filters (Low Pass and High Pass)
Active Band Pass Filter
Tschebyscheff Filter
Fiber Optic Analog Link
Owen’s Bridge
Anderson’s Bridge
RC – Coupled Amplifier with Feedback
Wien Bridge Oscillators
Colpitt Oscillator
Hartley Oscillator
RLC Series and RLC Parallel Resonance
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
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AB59
………… and many more
THEORY
An A.C. bridge, in its basic form, consists of four arms; a source of
excitation and a balance detector .In an A.C. bridge each of four arms are
impedance, and the A.C source and a detector sensitive to small alternating
potential differences.
The usefulness of A.C. bridge circuits is not restricted to the measurement
of unknown impedances and associated parameters like inductance,
capacitance, storage factor etc. These circuits find other application in
communication system and complex electronics circuits. A.C. bridges are
commonly used for phase shifting, providing feedback paths for oscillators
and amplifiers, filtering out undesirable signals and measuring the
frequency of audio signals.
For measurement at low frequencies, the power line may act as the source
of the supply to bridge circuits. For higher frequencies electronic
oscillators are universally used as bridge source supplies. These oscillator s
have the advantage that the frequency is constant easily adjustable and
determinable with accuracy the waveform is very close to a sine wave, and
their power output is sufficient for most bridge measurements.
Detectors most commonly used for a.c. bridges are
1.
Head phones
2.
Vibration galvanometers
3.
Tunable amplifiers detectors
Headphones are widely used as detectors at frequencies of 250 Hz and up
to 3 or 4 kHz. They are most sensitive detectors for this range.
When working at a single frequency a tuned detector normally gives the
greatest sensitivity and discrimination against harmonics in the supply.
Vibration galvanometer is extremely using for power and low audio
frequency ranges. Vibration galvanometers are manufactures to work at
various frequencies ranging from 5 Hz to 1000 Hz but are most commonly
used below 200 Hz, as below this frequency they are more sensitive that
the head phones.
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AB59
Tunable amplifiers detectors are the most versatile of the detectors .The
transistors amplifiers can be tuned electrically and thus can be made to
respond to a narrow bandwidth at the bridge frequency.
The output of the amplifier is fed to a pointer type instrument this detector
can be used, over a frequency range of 10 Hz to 100 kHz.
General equation for bridge balance
Basic a.c. bridge circuit is shown below the four arm of the bridge are
impedance Z1, Z2, Z3, Z4.
The condition for balance of bridge requires that there should be no current
through the detector. This requires that the potential difference between
point’s b and d should be zero. This will be the case when the voltage drop
from a to b equals the voltage drop from a to d, both in magnitude and
phase. In complex notation we can, thus, write:
E1 = E2
I1Z1 =I2Z2
Also at balance,
I1=I3 =E/Z1+Z2
I2=I4=E/Z2+Z4
Substituting the Eq. We Get
Z1Z4=Z2Z3
Eq. states that the product of impedances of one pair opposite arms must
equal the product of impedance of the other pair of opposite arms in
complex notation. This means that both magnitude and phase angle of the
impedance must be taken into account.
Two conditions must be satisfied simultaneously when balancing the a.c.
bridge
The first condition is that the magnitude of impedances satisfies the
relationship:
Z1 Z4=Z2Z3
The second condition is that the phase angles of impedance satisfy the
relationship:
θ1+θ4=θ2+θ3
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AB59
The phase angles are positive for inductive impedance and negative for
capacitance impedance.
MAXWELL’S INDUCTANCE BRIDGE
This Bridge is the simplest method of comparing two inductances and to
determine the values of unknown inductance. Figure 1 shows the basic
Maxwell’s Inductance Bridge circuit configuration.
Its first arm consisting of an non inductive resistance R1, second arm
consists of an standard inductor in series with the non inductive resistance
R3 used for resistance balance control, third arm consisting of variable
resistance R2 used for inductive balance control and fourth arm consists of
an unknown inductors with internal resistance Rx. The balance can be
obtained by varying the resistance R2 of third arm.
L1= inductor with unknown inductance,
Rx =internal resistance,
L3= standard inductor,
R1, R3 = non-inductive resistance.
At balance,
Z1Zx = Z2Z3
The value of Lx can be calculated by the formula:
Lx =L3R2/R1
The value of Rx can be calculated by the formula:
Rx =R2R3/R1
Where Lx is the value of unknown inductor and Rx is internal resistance.
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Lx
AB59
R2
RX
Vin
+
-
D
R3
R1
L3
Fig. 1
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AB59
EXPERIMENT
Objective :
To measure the value of unknown inductance with the help of
Maxwell’s Inductance Bridge
Apparatus required :
1.
Analog Board, AB59
2.
DC power supplies +/–12V from external source ST2612 Analog
lab
3.
Function generator ST4060
4.
2 mm patch cords.
5.
Digital multimeter
Circuit diagram :
Circuit used to measure the value of unknown inductance is shown in
Figure 2
Fig. 2
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AB59
Procedure :
•
Connect +/–12V dc power supply at their indicated position from
external source or ST2612 Analog lab.
1.
Connect function generator probes between Vin terminals.
2. Connect 2mm patch cord between sockets ‘a’ and ‘d’ and connect 2
mm patch cord between sockets ‘g’ and ‘h’ to determine the value of
Lx1 and Rx1.
3.
Switch ON the power supply and function generator.
4.
Set the 5Vpp, 1 KHz input sinusoidal signal of function generator.
5. Rotate the potentiometer R2 to find a condition where null or minimum
sound is generated.
6.
Switch off the power supply and function generator
7. Take the reading of potentiometer resistance R2 between test-points
‘Tp2’ and ‘Tp3’.
8. Calculate the value of capacitance Lx1 and Rx1 by their formulae.
9. Take the reading of unknown internal resistance Rx1 at socket ‘a’ and
test-point Tp2.
10. Connect 2mm patch cord between sockets ‘b’ and ‘d’ and connect 2
mm patch cord between sockets ‘f’ and ‘h’ to determine the value of
Lx2 and Rx2.
11. Repeat the above step from 3 to 8.
12. Take the reading of unknown internal resistance Rx2 at socket ‘b’ and
test-point Tp2.
13. Connect 2mm patch cord between sockets ‘c’ and ‘d’ and connect 2
mm patch cord between sockets ‘e’ and ‘h’ to determine the value of
Lx3 and Rx3.
14. Repeat the above step from 3 to 8.
15. Take the reading of unknown internal resistance Rx3 at socket ‘c’ and
test-point Tp2.
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AB59
OBSERVATION TABLE
S.
No.
R1
Ω
R2
Ω
L3
µh
Lx=L3R2/R1
µh
Rx’ =R2R3/R1Rx
Ω
1
2
3
Note : Values of R1, R3, and L3 are indicated on the front of the board and
by Rx’ we mean Rx1, Rx2 or Rx2 respectively.
Calculation :
Measured value of R2 is. ……..Ω
Now measure the value of Lx by the formula:
Lx=L3R2/R1
Measured value of resistance Rx by multimeter between sockets… Ω
Now measure the values of Rx’ by the formula
Rx’ =R2R3/R1- Rx
Result :
The inductance for Lx is measured to be = …….…μh
The internal resistance is = ……….Ω.
Note :
Value of inductors Lx1=12μh,
Value of inductors Lx2=1.2μh,
Value of inductors Lx3= 4.7μh,
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and value of Rx is 470 Ω.
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AB59
DATASHEETS
Scientech Technologies Pvt. Ltd.
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AB59
Scientech Technologies Pvt. Ltd.
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AB59
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.
DISPATCH 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 full
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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AB59
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.
New no.2, Old no.10, 4th street
Venkateswara nagar, Adyar
CHENNAI – 600025
4. Scientech Technologies Pvt. Ltd.
202/19, 4th main street
Ganganagar,
BANGALORE- 560032
5. Scientech Technologies Pvt. Ltd.
8,1st floor, 123-Hariram Mansion,
Dada Saheb Phalke road,
Dadar (East),
MUMBAI –400014
6. Scientech Technologies Pvt. Ltd.
988, Sadashiv Peth,
Gyan Prabodhini Lane,
PUNE – 411030
7. Scientech Technologies Pvt. Ltd
SPS Apartment, 1st Floor
2, Ahmed Mamoji Street,
Behind Jaiswal Hospital,
Liluah, HOWRAH-711204 W.B.
8. Scientech Technologies Pvt. Ltd
Flat No. 205, 2nd Floor,
Lakshminarayana Apartments
‘C’ wing, Street No. 17,
Himaytnagar,
HYDERABAD- 500029
Scientech Technologies Pvt. Ltd.
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
Email : chennai@scientech.bz
Ph : (080) 51285011
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Email : pune@scientech.bz
Ph : +913355266800
Email : kolkata@scientech.bz
Ph : (040) 55465643
Email : hyd@scientech.bz
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AB59
LIST OF ACCESSORIES
1.
2mm Patch cords (Red) ..............................................................3 Nos.
2.
2mm Patch cord (Black) .............................................................2Nos.
3.
2mm Patch cord (Blue) ...............................................................2Nos.
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