AB14
DARLINGTON PAIR
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.
AB14
Tel.: 91-731-2570301 Fax: 91-731-2555643
Email: info@scientech.bz Web: www.scientech.bz
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DARLINGTON PAIR
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TABLE OF CONTENTS
1.
Introduction
4
2.
Theory
6
3.
Experiments
•
Experiment 1
To calculate the current gain of Darlington pair and β
of transistor
9
•
Experiment 2
To calculate the voltage gain of Darlington pair using
Voltage divider biasing
11
Datasheet
13
4.
Warranty
15
5.
List of service Centers
16
6.
List of Accessories with AB14
17
7.
Notes
18
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INTRODUCTION
AB14 is a compact, ready to use DARLINGTON PAIR experiment board.
This board is useful for students to understand the working and operation of
Darlington pair configuration. 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.
List of Boards :
Model
Name
AB01
AB02
AB03
AB04
AB05
AB06
AB07
AB08
AB09
AB10
AB11
AB12
AB13
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
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
AB28
AB29
AB30
AB31
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AB32
AB33
AB35
AB39
AB41
AB42
AB43
AB44
AB45
AB49
AB51
AB52
AB53
AB54
AB56
AB57
AB58
AB59
AB65
AB66
AB67
AB68
AB80
AB81
AB82
AB83
AB84
AB85
AB88
AB89
AB90
AB91
AB92
AB93
AB96
AB97
AB101
AB102
AB106
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
Notch Filter
Tschebyscheff Filter
Fiber Optic Analog Link
Owen’s Bridge
Anderson’s Bridge
Maxwell’s Inductance Bridge
Phase Shift Oscillator
Wien Bridge Oscillators
Colpitt Oscillator
Hartley Oscillator
RLC Series and RLC Parallel Resonance
Kirchoff’s Laws (Kirchoff’s Current Law & Kirchoff’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
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……… and many more
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THEORY
In recent years, electronics have been integrated into motor speed drives
and a variety of switching-type power supplies. This meant that standard
discrete components needed to be altered to provide better characteristics.
The need for the Darlington pair grew from the limitations of SCRs and
triac-type thyristors. Thyristors control current by delaying the turn-on time.
The later the pulse is applied to turn them on, the smaller the amount of
current they will conduct during each cycle. On the other hand, a transistor
uses variable current (0 to saturation), which provides an output current that
will be a duplication of the input. This means the transistors will produce an
analog signal when an analog signal is provided to its base. The simple
bipolar transistor has several limitations including slow switching speeds,
low gains, and larger power losses due to the switching process. A family of
high-gain transistors called metal-oxide semiconductor field effect
transistors (MOSFETs) was produced to address the gain problem, but they
did not have the capability of controlling larger currents, so the Darlington
pair was designed. The Darlington pair can actually be two discrete
transistors that are connected in the driver/output configuration, or they can
be a single device that has the two transistors internally connected at the
point where it was manufactured as a single package.
For large currents it is standard and good procedure to use a Darlington pair
of transistors, rather than a single one, which effectively acts like a single
transistor with ß that is the product of the two ßs of the individual
transistors.
Darlington transistors are circuits that combine two bipolar transistors in a
single device. They provide high current gain (β) and require less space
than configurations that use two discrete transistors. In Darlington pairs,
transistor collectors are tied together and the emitter of the first transistor is
directly coupled to the base of the second transistor. The total gain, which is
often 1000 or more, is the product of the gain of the individual transistors.
Advantages and Disadvantages :
The key advantage of the Darlington configuration is that the total current
gain of the circuit equals the product of the current gain of two devices
since its current gain is much higher, Darlington connection can have a very
high input impedance and can produce very large outputs current
.Darlington connections are used with voltage regulators and power
amplifiers. The disadvantage is the larger saturation voltage compared to
single transistor configurations. Darlington transistor pairs have more phase
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shift at high frequencies and can become unstable with negative feedback
more easily. Darlington transistors also have a higher base-emitter voltage,
which is the sum of both base emitter voltages. Figure 1 shown below is a
Darlington pair since the emitter current of Q1 is the base current for Q2,
the darlington pair has an overall current gain of :
β=β1β2
……………. (1)
Semiconductor manufacturers can put a darlington pair inside a single case
like fig 2 known as Darlington transistor ,acts like a single transistor with a
very high current gain.
NPN Darlington Pair
Fig. 1
Darlington Transistor
Fig. 2
Complementary Darlington
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Fig. 3
Complementary Darlington is a connection of npn and pnp transistors .the
collector current of q1 is the base current of q2. if the pnp transistor has a
current gain of β1 and the npn output transistor has a current gain of β2 the
complementary Darlington acts like a single pnp transistor with a current
gain of β1 β2.The Complementary Darlington is sometimes used is class B
push-pull power amplifiers.
Input Current and Input Impedance measurement :
Fig. 4
Vin’ is the signal applied with Rs.
Vin is the signal at the input terminal of the Darlington pair with Rs.
Ii is the input current of the Darlington pair which can be measured using
the formula
(Vin’-Vin)/Rs
………………(2)
Input Impedance can be measured by
Zin =Vin/Ii
……………..(3)
Note: The range of β for TIP31C lies between 90 to 110.
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EXPERIMENT 1
Objective :
To calculate the current gain of Darlington pair and β of transistor.
Apparatus required :
1.
Analog board AB14.
2.
DC power supply +12V from external source or ST-2612 Analog
Lab.
3.
Function Generator ST-4064.
4.
Oscilloscope.
5.
Multimeter.
6.
2mm patch chords.
Circuit diagram :
Circuit used to study the operation of Darlington Pair is shown below :
Fig. 5
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Procedure :
• Connect +12V variable dc power supplies at their indicated position
from external source or ST-2612 Analog Lab.
1.
Connect +5V dc at Vin’ terminal and connect a patch cord between
socket a and socket b.
2.
Connect a patch cord between socket e and f.
3.
Now measure the dc voltage between base of transistor T1 and using
multimeter.
4.
Calculate the input current (Ii) by substituting the value in eq.2
5.
Now connect +5V directly at the base terminal of transistor T1.
6.
Remove the patch cord between socket e and f and connect a
multimeter between these sockets to measure the output current (Iout).
7.
Calculate the input impedance by using eq.3
8.
Calculate the ratio of output current to input current.
9.
Ratio of output current to input current gives the overall β of
Darlington pair.
10.
Individual β of transistors can be calculated by considering the
transistors having identical β and substituting in eq.1
Result :
Current Gain of Darlington Pair [Iout / Ii] = ………
Individual β of transistor =.........
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EXPERIMENT 2
Objective :
To calculate the voltage gain of Darlington pair using voltage divider
biasing.
Apparatus required :
1.
Analog board AB14.
2.
DC power supply +12V from
3.
Function Generator ST-4064.
4.
Oscilloscope.
5.
2mm patch chords.
Circuit diagram :
Circuit used to study the voltage gain of Darlington Pair is shown below :
Fig. 6
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Procedure :
•
Connect +12V variable dc power supplies at their indicated position
from external source or ST-2612 Analog Lab.
1.
Connect a patch cord between socket b and d and also between socket e
and f.
2.
Connect 1Vp-p, 1 KHz sine wave signal at the input (between points
Vin and) of amplifier of AB14 board and observe the same on
oscilloscope CH I.
3.
Observe the output waveform between points Vout and on oscilloscope
CH II.
4.
Measure the amplitude of the output waveform on oscilloscope.
5.
Calculate the voltage gain Av =Vout/Vin.
Result :
Voltage gain of Darlington pair = ………………………...
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DATASHEET
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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.
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,
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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HYDERABAD- 500029
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LIST OF ACCESSORIES
1.
2mm patch cord (red)................................................................ 1 Nos.
2.
2mm patch cord (blue).............................................................. 2 Nos.
3.
2mm patch cord (black)............................................................ 3 Nos.
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NOTES
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NOTES
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NOTES
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