AB16
Common Collector Amplifier
Operating Manual
Ver.1.1
An ISO 9001 : 2000 company
94-101, Electronic Complex Pardesipura,
Indore- 452010, India
Tel : 91-731- 2570301/02, 4211100
Fax: 91- 731- 2555643
e mail : info@scientech.bz
Website : www.scientech.bz
Toll free : 1800-103-5050
AB16
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AB16
Common Collector Amplifier
AB16
Table of Contents
1.
Introduction
4
2.
Theory
6
3.
Experiment
Study of Common Collector Amplifier (NPN) and evaluation :
11
I.
II.
III.
Operating Point of the Common Collector
Amplifier Voltage gain of the Amplifier AV.
Input and output impedance of Amplifier.
Current gain of Amplifier.
4.
Data Sheet
13
5.
Warranty
15
6.
List of Accessories
15
7.
RoHS Compliance
Scientech Products are RoHS Complied.
RoHS Directive concerns with the restrictive use of Hazardous substances (Pb,
Cd, Cr, Hg, Br compounds) in electric and electronic equipments.
Scientech products are “Lead Free” and “Environment Friendly”.
It is mandatory that service engineers use lead free solder wire and use the
soldering irons upto (25 W) that reach a temperature of 450°C at the tip as the
melting temperature of the unleaded solder is higher than the leaded solder.
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Introduction
AB16 is a compact, ready to use Common Collector Amplifier experiment board.
This is useful for students to understand the functionality of common collector
amplifier and to study various operational parameters of an transistor Amplifier. 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
AB14
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
Darlington Pair
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
DC Ammeter
Instrumentation Amplifier
AB28
AB29
AB30
AB31
AB32
AB33
AB35
AB39
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AB41
AB42
AB43
AB44
AB45
AB49
AB51
AB52
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
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
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
Amplification is the process of increasing the strength of signal. An Amplifier is a
device that provides amplification (the increase in current, voltage or power of signal)
without appreciably altering the original signal.
A Bipolar transistor is frequently used as an amplifier. A bipolar transistor is a current
amplifier, having three terminals Emitter, Base, Collector. A small current into base
controls a large current flow from the collector to emitter. The large current flow is
independent of voltage across the transistor from collector to emitter. This makes it
possible to obtain a large amplification of voltage by taking the output voltage from a
resistor in series with the collector.
Transistor can be used as an Amplifier in three configurations:
1.
Common Base
2.
Common Emitter
3.
Common Collector
Common Collector Configuration :
In this arrangement, the input signal is applied between base and collector and the
output is taken from the emitter and collector. In this arrangement input current is
base current and output current is emitter current.
Figure 1
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Current relations in CC configurations
IE = IC + IB
IE = γ * IB + γ * ICBO
γ = IE / IB
Where
IB = Base current (input current)
IC = Collector current
IE = Emitter current (output current)
ICEO = current through collector to emitter when base is open.
γ = current amplification in CC configuration.
Operation of Common Collector amplifier :
In order to get faithful amplification, the transistor is properly DC biased. The
purpose of DC biasing is to obtain a certain DC Emitter current (IC) at a certain DC
Emitter voltage (VEC). These values of current and voltage are called operating point
(Quiescent point). To obtain DC operating point some biasing methods are used
called biasing circuits. These biasing arrangements should be such as to operate the
transistor in Active region.
The Most commonly used Biasing circuits is voltage divider method. In this method
two resistances R1 and R2 are connected across the supply voltage VCC and provide
proper biasing. A voltage divider formed by R1 and R2, and the voltage drop across R2
Forward biased the base emitter junction causes the base current and hence collector
current flows in zero signal condition. Resistance RE provides stabilization.
V2 = VCC * R2 / (R1 + R2)
V2 = VBE + VE
V2 = VBE + IER
IE = (V2 - VBE) / RE
IE is approximately equal to IC.
IC = (V2 - VBE) / RE
VCE = VCC - IC (RC + RE)
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Figure 2
This method is widely used because operating point of transistor can be made almost
independent of beta (β) and provides good stabilization of operating point.
If this circuit is used to amplify AC voltages, some more components must be added
to it.
Coupling Capacitors (C1 &C3): They are used to pass AC input signal and block the
DC voltage from the preceding circuit. This prevents DC in the circuitry on the left of
coupling capacitor from affecting the bias on transistor. The coupling capacitor also
blocks the bias of transistor from reaching the input signal source. It is also called
blocking capacitor. Bypass Capacitors (C2): It bypasses all the AC current from the
emitter to the ground. If the capacitor C2 is not put in the circuit, the AC voltage
developed across RE will affect the input AC voltage, such a feedback is reduced by
putting the capacitor C2.
RE: It represents the load resistance is connected at the output.
In this amplifier input signal is injected into the base-collector circuit and output
signal is taken out from the Emitter-Collector Circuit, When the output is taken from
emitter terminal of transistor this network is referred as Emitter Follower or Common
Collector Amplifier. In this amplifier output voltage is always less than the input
signal, and output voltage is in phase with the input voltage. The fact that output
voltage follows the magnitude of input voltage with an in-phase relationship accounts
for the terminology "Emitter Follower".
When positive half cycle of the signal is applied then,
1.
Forward biased is increased, since Vbe is positive w.r.t. collector i e. Ground.
2.
Base current is increased,
3.
Emitter current is increased,
4.
Drop across Re is increased,
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5.
Hence output voltage is increased; consequently positive half-cycle of the output
is obtained. i.e. input and output are in phase with each other.
Figure 3
Operating Parameter of Common Collector Amplifier :
Voltage Gain :
The ratio or Output Voltage (Vo) to the input voltage (Vi) is known as voltage
amplification or voltage gain of amplifier.
Voltage Gain (AV) = VO / Vi
Input Impedance :
It is the ratio of Input voltage (Vin) to Input current (Ii)
Zin = Vin / Ii
To measure the input impedence a known resistor (Rs) is placed in series before the
input coupling capacitor and the impedence could be calculated using the equation
Zin = Rs / (Av/Av`- l)
Where
Av = voltage gain without the resistor (Rs)
Av` = voltage gain with the resistor (Rs)
Figure 4
Output Impedence : It is the ratio of Output voltage (Vout) to Output Current (Io).
Zout = Vout / Io
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To measure the Output impedance a known resistor (Rs) is placed from output to
ground and the output impedance could be calculated using the equation
Zout = (Av / Av`-l) * Rs
Where
Av = voltage gain without the resistor (Rs)
Av` = voltage gain with the resistor (Rs)
Current gain :
It is the ratio of Output current (Io) to Input current (Ii).
Ai = IO / Ii
The Current gain could be calculated using the equation
Ai = - Av * Zin / RL
Characteristics of Common Collector Amplifier :
1.
It produces no phase reversal, i.e., input and output signals are in phase with
each other.
2.
It has voltage gain of less than 1.
3.
It has very high input impedance.
4.
It has low output impedance.
5.
It has high current gain (β + 1).
Comparisons of Amplifiers Configurations :
Type of Amplifier Circuit
Characteristic
Common
Base
Common
Emitter
Common
Collector
Phase reversal
No
Yes
No
Voltage Gain
High
Highest
Nearly Unity
Input
Impedance
Lowest
Moderate
Highest
Output
Impedance
Highest
Moderate
Lowest
Current Gain
Nearly unit
High (β)
Highest (β + 1 )
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Experiment
Objective :
Study the Common Collector Amplifier and to evaluate –Operating Point,
Voltage gain (AV), input and output impedance, current gain of amplifier.
Equipments Needed :
1.
Analog board of AB16.
2.
DC power supply +12V external source or ST2612 Analog Lab.
3.
Digital Multimeter
4.
2 mm patch cords
Circuit diagram :
Circuit used to study Common Collector Amplifier is shown in figure 5.
Figure 5
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Procedure :
1.
Connect test point 2 and test point 3, test point 4 and test point 5, test point 6
and test point 7, using 2mm patch cords.
2.
Connect +12V DC power supply at their indicated position from external source
or ST2612 Analog Lab.
3.
Switch ‘On’ the power supply.
4.
For the measurement of Quiescent Point measure the VEC by connecting
voltmeter between test point 4 and test point 6. Measure Emitter current (IE) by
connecting ammeter between test point 6 and test point 7.
5.
Connect a sinusoidal signal of 10mV (p-p) at 25 KHz frequency at the Test
point 1 (Input of amplifier).
6.
Observe the amplified output on oscilloscope by connecting test point 8 (output
of amplifier) to oscilloscope.
7.
Calculate Voltage gain of amplifier. Connect Load resistor of 1K ohms at the
output and find the voltage gain of amplifier with load resistor.
8.
Calculate input impedance, output impedance, and current gain of amplifier
using the mentioned formulas with resistance 1 K.
Result :
Operating Point of the Common Collector Amplifier
IC = ________ mA
VEC = _________V
Voltage gain of the amplifier AV _________ =
Input impedance of amplifier Zin _________ =
Output Impedance of amplifier Zout _______ =
Current gain of amplifier Ai
= ____________
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Data Sheet
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Warranty
1.
We guarantee the product against all manufacturing defects for 24 months from
the date of sale by us or through our dealers. Consumables like dry cell etc. are
not covered under warranty.
2.
The guarantee will become void, if
a)
The product is not operated as per the instruction given in the operating
manual.
b)
The agreed payment terms and other conditions of sale are not followed.
c)
The customer resells the instrument to another party.
d)
Any attempt is made to service and modify the instrument.
3.
The non-working of the product is to be communicated to us immediately giving
full details of the complaints and defects noticed specifically mentioning the
type, serial number of the product and date of purchase etc.
4.
The repair work will be carried out, provided the product is dispatched securely
packed and insured. The transportation charges shall be borne by the customer.
For any Technical Problem Please Contact us at service@scientech.bz
List of Accessories
1.
2mm Patch Cord (Red) 16” .....................................................................1 No.
2.
2mm Patch Cord (Black) 16”................................................................. 3 Nos.
3.
2mm Patch Cord (Blue) 16” .................................................................. 5 Nos.
4.
e-Manual.................................................................................................1 No.
Updated 26-06-2009
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