Download AB88 Diode Clippers

AB88
Diode Clippers
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 : [email protected]
Website : www.scientech.bz
Toll free : 1800-103-5050
AB88
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AB88
Diode Clippers
AB88
Table of Contents
1.
Introduction
4
2.
Theory
6
3.
Experiments
•
Experiment 1
Study of Parallel positive and negative clipper
11
•
Experiment 2
Study of series positive and series negative clipper
13
•
Experiment 3
Study of combination clipper
15
4.
Warranty
16
5.
List of Accessories
16
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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AB88
Introduction
AB88 is a compact, ready to use Diode clippers experiment board. This is useful for
students to understand basics of diodes and clipping circuits. It 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
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
Darlington Pair
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
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)
AB28
AB29
AB30
AB31
AB32
AB33
AB35
AB39
AB41
AB42
AB43
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AB44
AB45
AB49
AB51
AB52
AB54
AB56
AB57
AB58
AB59
AB64
AB65
AB66
AB67
AB68
AB80
AB82
AB83
AB84
AB85
AB89
AB90
AB91
AB92
AB93
AB96
AB97
AB101
AB102
AB106
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 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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AB88
Theory
Clippers :
The circuit with which the waveform is shaped by removing (or clipping) a portion of
the applied wave is known as a clipping circuits. This kind of processing is useful for
signal shaping, circuit protection, radars, digital and other electronic systems. In other
words clippers have the ability to “clip” off a portion of the input signal without
distorting the remaining part of the incoming wave. The simplest form of clipping
circuits is Diode clippers. The basic of Diode clipper is – one resistance and a diode.
These clippers can remove signal voltages above or below a specified level
.Depending on the orientation of the diode, clippers are classified as1.
Positive clippers
2.
Negative clippers
3.
Combination clippers
There are two general categories of clippers1.
Series clippers
2.
Parallel clippers
Positive clippers :
A positive clipper is that which removes the positive half-cycles of the input voltage
figure 1 shows the circuit of positive clipper using a diode.
Figure 1
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AB88
How the circuit works ?
During the positive half cycle, the diode turns on and looks like a short across the
output terminals .Ideally, the output voltage is zero. On the negative half cycle, the
diode is open. In that case, a negative cycle appears across the output. But practically
silicon diode takes 0.7V for conduction and a germanium diode takes 0.3V for
conduction. This 0.7V and 0.3V is called clipping level or reference level of diode.
Therefore the clipping level is not zero, but 0.7V.
Suppose the input signal has a peak value of 10V, the output of clipper will look like
figure 2.
Figure 2
Negative clippers :
A negative clipper is that which removes the negative half-cycles of the input voltage.
If we reverse the polarity of the diode in positive clipper circuit, we get a negative
clipper.
Figure shows the circuit of negative clipper. The clipping level is at -0.7V. Suppose
the input signal has a peak of 10V, the ideal output signal will look like as figure 3(a)
and practical signal will look like as figure 3(b).
Figure 3a
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Figure 3b
These both positive and negative clippers circuits are the type of parallel clipper. The
parallel configuration is defined as one where the diode is in a branch parallel to the
load.
Series clippers :
The series configuration is defined as one where the diode is in series with the load
figure 4 (a) shows series negative clipper. During the positive half cycle, the diode
turns on and looks like a short across the output terminals Ideally, complete positive
cycle getting in output. On the negative half cycle, the diode is open. In that case, zero
voltage appears across the output. This circuit ideally behaves as a half wave rectifier.
The output signal looks like as figure 4(a).
Negative series clipper
Figure 4a
Positive series clipper
Figure 4b
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AB88
Figure 4(b) shows positive series clipper. The functionality of this circuit is exactly
opposite to series negative clipper. During the positive half cycle of the input signal,
diode is open this gives zero voltage at output. During the negative half cycle, the
diode turns on and looks like a short across the output terminal .The output voltage is
shown in figure 4 (b).
Biased Clipper :
The reference level or clipping level of a positive clipper is ideally zero or 0.7V
practically. If we want to change this reference level we add bias in the circuit.
Bias means applying an external voltage to change the reference level. By adding a
DC voltage source in series with a diode, we can change the clipping level of positive
clipper. But limitation is that a new V must be less than Vm of our normal operation.
Figure 5 shows the circuit of biased positive clipper and biased negative clipper.
Examine the output wave amplitude in both circuits.
Biased positive clipper
Figure 5a
Biased Negative clipper
Figure 5b
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Combinational clipper :
Combination clipper is a combination of biased positive and negative clipper. With a
combination clipper, a portion of both positive and negative half cycles of input
voltage can be removed or clipped. From figure 6 Diode D1 clips off positive parts
above the positive bias level, and diode D2 clips off parts below the negative bias
level.
When positive input voltage is greater than +V1 , diode D1 conducts heavily while
diode D2 remains reverse biased .Therefore, a voltage +V1 appears across the load.
This output stays at +V1 as long as the input voltage exceeds +V1. On the other hand,
during the negative half cycle, the diode D2 will conduct heavily and output stays at –
V2 so long as the input voltage is greater than –V2.
Between +V1 and –V2 neither diode is on. Therefore, in this condition, most of the
input voltage appears across the load.
Using batteries for low voltage is impractical. We give variable voltage source by
vary a resistance. Figure 6 gives the circuit of combination clipper. Examine the
amplitude of output wave.
Figure 6
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AB88
Experiment 1
Objective : Study of Parallel positive and parallel negative clipper
Equipments Needed :
1.
Analog board AB88
2.
DC power supplies +5V and -5V from external source or ST2612 Analog Lab.
3.
Oscilloscope Caddo 802 or equivalent
4.
Function generator
5.
2 mm patch cords
Circuit diagram :
This experiment investigates the generation of positive and negative clipped
waveform across the diode.
Figure 7
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Procedure :
•
Connect +5V and -5V DC power supplies at their indicated position from
external source or ST2612 Analog Lab.
1.
With the help of function generator set sine wave of 1 KHZ frequency and
amplitude 2Vpp approximately this is the input signal of clipper which we want
to clip.
2.
Give input signal to terminal a.
3.
Monitor output signal at terminal b with the help of oscilloscope. This is the
output of positive parallel clipper.
4.
Disconnect input to terminal a and connect it to terminal c.
5.
Monitor output signal at terminal d with the help of oscilloscope. This is the
output of negative parallel clipper.
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AB88
Experiment 2
Objective : Study of series positive and series negative clipper
Equipments Needed :
1.
Analog board AB88
2.
DC power supplies +5V and -5V from external source or ST2612 Analog Lab.
3.
Oscilloscope Caddo or equivalent
4.
Function generator
5.
2 mm patch cords
Circuit diagram :
This experiment investigates the generation of positive and negative clipped
waveform at the diode.
Figure 8
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AB88
Procedure :
•
1.
Connect +5V and -5V DC power supplies at their indicated position from
external source or ST2612 Analog Lab.
With the help of function generator set sine wave of 1 KHZ frequency and
amplitude 2Vpp approximately this is the input signal of clipper which we want
to clip.
2.
Give input signal to terminal e.
3.
Monitor output signal at terminal f with the help of oscilloscope. This is the
output of positive series clipper.
4.
Disconnect input to terminal e and connect it to terminal g.
5.
Monitor output signal at terminal h with the help of oscilloscope. This is the
output of Negative series clipper.
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AB88
Experiment 3
Objective :
Study of combination clipper
Equipments Needed :
1.
Analog board AB88
2.
DC power supplies +5V and -5V from external source or ST2612 Analog Lab.
3.
Oscilloscope Caddo 802 or equivalent
4.
Function generator
5.
2 mm patch cords
Circuit diagram :
This experiment investigates the generation of positive and negative clipped
waveform by combination clipper.
Figure 9
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AB88
Procedure :
1.
With the help of function generator set sine wave of 1KHZ frequency and
amplitude 10Vpp approximately this is the input signal of clipper which we
want to clip.
2.
Give input signal to terminal k.
3.
Monitor output signal at terminal m, with the help of oscilloscope.
4.
Turn the potentiometer near VA, on the board, to its fully clockwise position.
This is the variable DC voltage which we want to add in series with diode to
achieve a clipping level.
5.
Turn the potentiometer near VB, on the board, to its fully clockwise position.
This is the variable DC voltage which we want to add in series with diode to
achieve a clipping level.
6.
Vary the potentiometer and examine the effect of adding DC voltage at terminal
m.
7.
Examine the level of DC voltage at TP1 and TP2, with the help of AC/DC
switch on the oscilloscope or multimeter.
8.
If zero DC voltage is present on TP2 and only vary TP1 at that time circuit act
like as positive biased clipper. Examine the output at terminal m.
9.
If zero DC voltage is present on TP1 and only vary TP2 at that time circuit act
like as negative biased clipper. Examine the output at terminal m.
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AB88
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 [email protected]
List of Accessories
1.
2mm Patch Cord (Red) 16” ................................................................ 2 Nos.
2.
2mm Patch Cord (Black) 16”.............................................................. 3 Nos.
3.
2mm Patch Cord (Blue) 16” ............................................................... 2 Nos.
4.
e-Manual.............................................................................................. 1 No.
Updated 26-06-2009
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