AB51
ACTIVE FILTERS
LOW PASS AND HIGH PASS
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
AB51
Email: info@scientech.bz Web: www.scientech.bz
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LOW PASS AND HIGH PASS ACTIVE FILTERS
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TABLE OF CONTENTS
1.Introduction
4
2. Theory
6
3.Experiment 1
To study the Active Low pass filter.
9
4.Experiment 2
To study the Active High Pass filter.
12
5.Datasheet
15
6.Warranty
16
7.List of Service Centers
17
8.List of Accessories with AB51
18
9. Notes
19
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INTRODUCTION
AB51 is a compact, ready to use ACTIVE FILTERS experiment board. It
incorporates Low pass filter and High pass filter on a single board and
illustrates the functionality of Active filters at adjustable cutoff frequency.
It can be used as stand alone unit with external 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 potentiometers.
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
AB28
AB29
AB30
AB31
AB32
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
Multivibrator ( Mono stable / Astable)
F-V and V-F Converter
V-I and I-V Converter
Zener Voltage Regulator
Transistor Series Voltage Regulator
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AB51
AB33
AB35
AB39
AB41
AB42
AB43
AB44
AB45
AB49
AB52
AB53
AB54
AB56
AB57
AB58
AB59
AB64
AB65
AB66
AB67
AB68
AB80
AB82
AB83
AB84
AB85
AB88
AB89
AB90
AB91
AB92
AB93
AB96
AB97
AB101
AB102
AB106
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 Band Pass Filter
Notch Filter
Tschebyscheff Filter
Fiber Optic Analog Link
Owen’s Bridge
Anderson’s Bridge
Maxwell’s Inductance Bridge
RC – Coupled Amplifier with Feedback
Phase Shift Oscillator
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
………… and many more
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THEORY
An electric filter is a frequency selective circuit that passes electric signals
of specific band of frequencies and attenuates signal of frequencies outside
this band. Depending on the type of elements used in their construction
filters may be classified as passive or active filters. Elements used in
passive filters are resistors, capacitors and inductors. Active filter consists
of active components such as Op-amp, transistors with passive elements.
Most commonly used filters are:
1.
Low pass Filter
2.
High pass filter
3.
Band pass filter
Low Pass filter :
It is a frequency selective circuit, which passes signals of frequency below
it’s high cut off frequency (fh) and attenuates signals of frequency above fh.
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Fig. 1
Equation of low pass filter is
Vin = Input signal Voltage
Vout = Output signal Voltage
AF = 1 + RF / R1 = pass band gain of filter
f = frequency of input signal
fH = 1/2πRC = high cut off frequency, 3-db frequency, corner frequency
Operation of low pass filter using equation 2
The ideal low pass filter has a constant gain AF from 0 to high cut off
frequency (fH) at fH the gain is 0.707 * Af. And after fH it decreases at a
constant rate with an increase in frequency i.e. when input frequency is
increased tenfold (one decade), the voltage gain is divided by 10.
Gain (db) = 20 log | Vout / Vin |
i.e. Gain Roll off rate is −20db / decade.
High Pass filter
It is a frequency selective circuit, which passes signals of frequencies above
it's low cut off frequency (fL) and attenuates signals of frequencies below fL.
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Fig. 2
Equation of High pass filter is
Vin = Input signal Voltage
Vout = Output signal Voltage
AF = 1 + RF / R1 = pass band gain of filter
f = frequency of input signal
fL = 1/2 π RC = Low cut off frequency, 3-db frequency, corner frequency
Operation of high pass filter using equation.
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In ideal high pass filter, when f < fL gain is increased at a constant rate has a
constant rate with an increase in frequency. At fL the gain is 0.707*AF. And
above fL it has constant gain of AF. Below fL when input frequency is
increased tenfold (one decade), the voltage gain is multiplied by 10.
Gain (db) = 20 log | Vout / Vin |
i.e. Gain Roll off rate is −20db / decade.
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EXPERIMENT 1
Object :
To study the Active Low pass filter and to evaluate :
•
•
•
High cutoff frequency of Low pass filter.
1.
2.
Analog board of AB51.
Pass band gain of Low pass filter.
Plot the frequency response of Low pass filter.
Apparatus Required :
DC power supplies +12V, −12V from external source or ST2612
Analog Lab.
3.
Function generator or ST2612 Analog Lab.
4.
Oscilloscope
5.
Digital Multimeter
6.
2 mm patch cords.
Circuit Diagram :
Circuit used to study Active Low pass filter shown in Fig 3.
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Fig. 3
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Procedure :
1.
Connect Ohmmeter between Test point Vin and Test point 1. Adjust
resistance value to 1.59K by varying the potentiometer 22K of Low
pass filter to set the high cutoff frequency (fH) at 10K.
2.
Connect +12V and −12V DC power supplies at their indicated
position from external source or ST2612 Analog Lab.
3.
Switch ON the power supply.
4.
Connect a sinusoidal signal of amplitude 1V (p-p) of frequency
1KHz to Vin of Low pass filter from external source or ST2612
Analog Lab.
5.
Observe output on oscilloscope by connecting Test point Vout to
oscilloscope.
6.
Increase the frequency of input signal step by step and observe the
effect on output Vout on oscilloscope.
7.
Tabulate values of Vout, gain, gain (db) at different values of input
frequency shown in observation Table.
Observation Table :
8.
Sr.
No.
Input
frequency
(Hz)
1
500
2
1K
3
5K
4
10 K (fH)
5
15 K
6
20 K
7
30 K
Vout |Vout / Vin| = gain
Gain(db) = 20
Log |vout / vin|
Plot the frequency response of low pass filter using the data obtained
at different input frequencies.
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9.
Perform the same procedure at different Cutoff frequencies as shown
below:
fH high cutoff
Capacitance (uF)
Resistance (Ω)
frequency (Hz)
800
0.01
20K
1.59 K
0.01
10K
15.9 K
0.01
1K
Theoretical Calculations :
Calculate all the following values
1.
Pass band gain of Low pass filter AF = 1 + RF / R1
2.
Pass band gain (db) = 20 log |Vout / Vin|
3.
3 db frequency fH = 1/2πRC
4.
Gain at 3 db frequency fH = 0.707 * AF
5.
Gain (db) at 3 db frequency fH = 20 log |Vout / Vin| where
Vout = (2)1/2 * Vin
6.
Roll off rate = −20db/decade
Results :
Theoretical
Practical
Pass band gain(Af)
Pass band gain(Af) in db
3db frequency fH
Gain at 3db frequency (fH ) in db
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EXPERIMENT 2
Object :
To study the Active High pass filter and to evaluate :
1.
2.
3.
Low cutoff frequency of Low pass filter.
1.
2.
Analog board of AB51.
Pass band gain of High pass filter.
Plot the frequency response of High pass filter.
Apparatus Required :
DC power supplies +12V, −12V from external source or ST2612
Analog Lab.
3.
Function generator or ST2612 Analog Lab.
4.
Oscilloscope
5.
Digital Multimeter
6.
2 mm patch cords.
Circuit Diagram :
Circuit used to study Active High pass filter shown in Fig 4.
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Fig. 3
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Procedure :
1.
Connect Ohmmeter between Vin and Testpoint 3. Adjust resistance
value to 15.9K by varying the potentiometer 22K of High pass filter
to set the Low cutoff frequency (fL) at 1K.
2.
Connect +12V and −12V DC power supplies at their indicated
position from external source or ST2612 Analog Lab.
3.
Switch ON the power supply.
4.
Connect a sinusoidal signal of amplitude 1V (p-p) of frequency
100 Hz to the Test point Vin of high pass filter from external source
or ST2612 Analog Lab.
5.
Observe output on oscilloscope by connecting Testpoint Vout to
oscilloscope.
6.
Increase the frequency of input signal step by step and observe the
effect on output Vout on oscilloscope.
7.
Tabulate different values of Vout, gain, gain (db) at different values
of input frequency shown in observation Table.
Observation Table :
Sr.
No.
Input
frequency
(Hz)
1
100
2
200
3
500
4
1K(fL)
5
5K
6
10 K
7
15 K
8
20 K
Vout |Vout / Vin| = gain
Scientech Technologies Pvt. Ltd.
Gain(db) = 20
Log |vout / vin|
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8.
Plot the frequency response of high pass filter using the data
obtained at different input frequencies.
9.
Perform the same procedure at different Cutoff frequencies as shown
below:
Resistance (Ω)
Capacitance (uF)
3 db frequency (Hz)
800
0.01
20K
1.59 K
0.01
10K
15.9 K
0.01
1K
Theoretical Calculations :
Calculate all the following values
1.
Pass band gain of Low pass filter AF = 1 + RF / R1
2.
Pass band gain (db) = 20 log |Vout / Vin|
3.
Low cutoff frequency fL = 1/2πRC
4.
Gain at Low cutoff frequency fL = 0.707 * AF
5.
Gain (db) at Low cutoff frequency fH = 20 log |Vout / Vin| where
Vout = (2)1/2 * Vin
6.
Roll off rate = −20db/decade
Results :
Theoretical
Practical
Pass band gain(Af)
Pass band gain(Af) in db
Low cutoff frequency (fL)
Gain at 3db frequency (fL ) in db
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DATASHEET
Scientech Technologies Pvt. Ltd.
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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. 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) 5202959
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
Fax: (080) 51285022
Email: bangalore@scientech.bz
Ph.: (022) 56299457
Fax: (022) 24168767
Email: stplmum@scientech.bz
Ph.: (020) 24461673
Fax: (020) 24482403
Email: pune@scientech.bz
Ph.: +913355266800
Email : kolkata@scientech.bz
Ph.: (040) 55465643
Email: hyd@scientech.bz
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LIST OF ACCESSORIES
1.
2mm Patch cord (red) .............................................................2 Nos.
2.
2mm Patch cord (black) .........................................................3 Nos.
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NOTES
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NOTES
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