Transcript
AB59 Maxwell’s Inductance Bridge
Analog Lab Experiment Board Ver. 1.0
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Maxwell’s Inductance Bridge AB59 TABLE OF CONTENTS
1.Introduction
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2. Theory
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3.Maxwell’s Inductance Bridge
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4.Experiment To measure the value of unknown inductance with the help of Maxwell’s Inductance Bridge
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5.Observation table
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6.Datasheet
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7.Warranty
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8.List of Service Centers
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9.List of Accessories with AB59
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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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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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………… 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
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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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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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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
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R2 RX Vin +
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D
R3
R1 L3
Fig. 1
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EXPERIMENT Objective : To measure the value of unknown inductance with the help of Maxwell’s Inductance Bridge Apparatus required :
1.
Analog Board, AB59
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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
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Procedure :
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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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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, Scientech Technologies Pvt. Ltd.
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and value of Rx is 470 Ω.
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DATASHEETS
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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. 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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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.
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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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