This presentation contains the basic information you need to know about operational amplifier.
I have tried to cover all the basic info. If anything is left out or you have any suggestions i will appreciate it.
This presentation contains the basic information you need to know about operational amplifier.
I have tried to cover all the basic info. If anything is left out or you have any suggestions i will appreciate it.
Introduction
Semiconductor is a solid substance that has conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects. Devices made of semiconductors, notably silicon, are essential components of most electronic circuits.
Examples: Silicon, Germanium, Carbon
Intrinsic & Extrinsic Semiconductor
Semiconductors are mainly classified into two categories: Intrinsic and Extrinsic. An intrinsic semiconductor material is chemically very pure and possesses poor conductivity. It has equal numbers of negative carriers (electrons) and positive carriers (holes). Where as an extrinsic semiconductor is an improved intrinsic semiconductor with a small amount of impurities added.
The Doping of Semiconductors
The addition of a small percentage of foreign atoms in the regular crystal lattice of silicon or germanium produces dramatic changes in their electrical properties, producing n-type and p-type semiconductors.
Pentavalent impurities
Impurity atoms with 5 valence electrons produce n-type semiconductors by contributing extra electrons.
Trivalent impurities
Impurity atoms with 3 valence electrons produce p-type semiconductors by producing a "hole" or electron deficiency.
N-Type Semiconductor
The addition of pentavalent impurities such as antimony, arsenic or phosphorous contributes free electrons, greatly increasing the conductivity of the intrinsic semiconductor. Phosphorous may be added by diffusion of phosphine gas (PH3).
P-Type Semiconductor
The addition of trivalent impurities such as boron, aluminum or gallium to an intrinsic semiconductor creates deficiencies of valence electrons,called "holes". It is typical to use B2H6 diborane gas to diffuse boron into the silicon material.
Diodes
A device that blocks current in one direction while letting current flow in another direction is called a diode. Diodes can be used in a number of ways. For example, a device that uses batteries often contains a diode that protects the device if you insert the batteries backward. The diode simply blocks any current from leaving the battery if it is reversed -- this protects the sensitive electronics in the device.
this presentation is based on basic description of inverting and non-inverting amplifiers using op-amps and their medical use, hope it helps students :)
PowerPoint Presentation on using IC 555 Timer as an Astable Multi vibrator. Working of the astable multi vibrator, advantages and disadvantages of an Astable Multi-vibrator,Input and Output Pins of 555 IC, Formulae for calculating the charge and discharge time and cycle time of the astable multi vibrator.
Oscillators introduction and its types, phase shift oscillators and wein bridge oscillators,difference between phase shift and wein bridge, frequency stability, oscillators principle and conditions, block diagram of oscillators, block diagram of phase shift oscillators
Classification of signals and systems as well as their properties are given in the PPT .Examples related to types of signals and systems are also given .
Power point presentation on logical families.
A good presentation cover all topics.
For any other type of ppt's or pdf's to be created on demand contact -dhawalm8@gmail.com
mob. no-7023419969
Introduction
Semiconductor is a solid substance that has conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects. Devices made of semiconductors, notably silicon, are essential components of most electronic circuits.
Examples: Silicon, Germanium, Carbon
Intrinsic & Extrinsic Semiconductor
Semiconductors are mainly classified into two categories: Intrinsic and Extrinsic. An intrinsic semiconductor material is chemically very pure and possesses poor conductivity. It has equal numbers of negative carriers (electrons) and positive carriers (holes). Where as an extrinsic semiconductor is an improved intrinsic semiconductor with a small amount of impurities added.
The Doping of Semiconductors
The addition of a small percentage of foreign atoms in the regular crystal lattice of silicon or germanium produces dramatic changes in their electrical properties, producing n-type and p-type semiconductors.
Pentavalent impurities
Impurity atoms with 5 valence electrons produce n-type semiconductors by contributing extra electrons.
Trivalent impurities
Impurity atoms with 3 valence electrons produce p-type semiconductors by producing a "hole" or electron deficiency.
N-Type Semiconductor
The addition of pentavalent impurities such as antimony, arsenic or phosphorous contributes free electrons, greatly increasing the conductivity of the intrinsic semiconductor. Phosphorous may be added by diffusion of phosphine gas (PH3).
P-Type Semiconductor
The addition of trivalent impurities such as boron, aluminum or gallium to an intrinsic semiconductor creates deficiencies of valence electrons,called "holes". It is typical to use B2H6 diborane gas to diffuse boron into the silicon material.
Diodes
A device that blocks current in one direction while letting current flow in another direction is called a diode. Diodes can be used in a number of ways. For example, a device that uses batteries often contains a diode that protects the device if you insert the batteries backward. The diode simply blocks any current from leaving the battery if it is reversed -- this protects the sensitive electronics in the device.
this presentation is based on basic description of inverting and non-inverting amplifiers using op-amps and their medical use, hope it helps students :)
PowerPoint Presentation on using IC 555 Timer as an Astable Multi vibrator. Working of the astable multi vibrator, advantages and disadvantages of an Astable Multi-vibrator,Input and Output Pins of 555 IC, Formulae for calculating the charge and discharge time and cycle time of the astable multi vibrator.
Oscillators introduction and its types, phase shift oscillators and wein bridge oscillators,difference between phase shift and wein bridge, frequency stability, oscillators principle and conditions, block diagram of oscillators, block diagram of phase shift oscillators
Classification of signals and systems as well as their properties are given in the PPT .Examples related to types of signals and systems are also given .
Power point presentation on logical families.
A good presentation cover all topics.
For any other type of ppt's or pdf's to be created on demand contact -dhawalm8@gmail.com
mob. no-7023419969
Introduction to operational Amplifier. For A2 level physics (CIE). Discusses characteristics of op amp, inverting and non inverting amplifier, and voltage follower, and transfer characetristics, virtual earth , etc
33Analog Applications Journal August 2000 Analog and Mixed.docxgilbertkpeters11344
33
Analog Applications Journal August 2000 Analog and Mixed-Signal Products
Design of op amp sine wave oscillators
Criteria for oscillation
The canonical form of a feedback system1 is shown in
Figure 1, and Equation 1 describes the performance of
any feedback system (an amplifier with passive feedback
components constitutes a feedback system).
(1)
Oscillation results from an unstable state; i.e., the feed-
back system can’t find a stable state because its transfer
function can’t be satisfied. Equation 1 becomes unstable
when (1+Aβ) = 0 because A/0 is an undefined state. Thus,
the key to designing an oscillator is to insure that Aβ = –1
(called the Barkhausen criterion), or using complex math
the equivalent expression is Aβ = 1∠ –180°. The –180°
phase shift criterion applies to negative feedback systems,
and 0° phase shift applies to positive feedback systems.
The output voltage of a feedback system heads for
infinite voltage when Aβ = –1. When the output voltage
approaches either power rail, the active devices in the
amplifiers change gain, causing the value of A to change
so the value of Aβ ≠ –1; thus, the
charge to infinite voltage slows down
and eventually halts. At this point one
of three things can occur. First, non-
linearity in saturation or cutoff can cause
the system to become stable and lock
up. Second, the initial charge can cause
the system to saturate (or cut off) and
stay that way for a long time before it
becomes linear and heads for the oppo-
site power rail. Third, the system stays
linear and reverses direction, heading
for the opposite power rail. Alternative
two produces highly distorted oscilla-
tions (usually quasi square waves),
and the resulting oscillators are called
relaxation oscillators. Alternative three
produces sine wave oscillators.
All oscillator circuits were built with
TLV247X op amps, 5% resistors, and
β+
=
A1
A
V
V
IN
OUT
20% capacitors; hence, component tolerances cause differ-
ences between ideal and measured values.
Phase shift in oscillators
The 180° phase shift in the equation Aβ = 1∠ –180° is
introduced by active and passive components. Like any
well-designed feedback circuit, oscillators are made
dependent on passive component phase shift because it is
accurate and almost drift-free. The phase shift contributed
by active components is minimized because it varies with
temperature, has a wide initial tolerance, and is device-
dependent. Amplifiers are selected such that they con-
tribute little or no phase shift at the oscillation frequency.
A single pole RL or RC circuit contributes up to 90°
phase shift per pole, and because 180° is required for
oscillation, at least two poles must be used in oscillator
design. An LC circuit has two poles; thus, it contributes up
to 180° phase shift per pole pair, but LC and LR oscillators
are not considered here because low frequency inductors
are expensive, heavy, bulky, and non-ideal. LC oscillators
are designed in high-frequency applications, be.
An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave. Oscillators convert direct current (DC) from a power supply to an alternating current (AC) signal. They are widely used in many electronic devices. Common examples of signals generated by oscillators include signals broadcast by radio and television transmitters, clock signals that regulate computers and quartz clocks, and the sounds produced by electronic beepers and video games.
Oscillators designed to produce a high-power AC output from a DC supply are usually called inverters.
There are two main types of electronic oscillator: the linear or harmonic oscillator and the nonlinear or relaxation oscillator.
Electrical Engineering is the Branch of Engineering. Electrical Engineering field requires an understanding of core areas including Thermal and Hydraulics Prime Movers, Analog Electronic Circuits, Network Analysis and Synthesis, DC Machines and Transformers, Digital Electronic Circuits, Fundamentals of Power Electronics, Control System Engineering, Engineering Electromagnetics, Microprocessor and Microcontroller. Ekeeda offers Online Mechanical Engineering Courses for all the Subjects as per the Syllabus Visit : https://ekeeda.com/streamdetails/stream/Electrical-Engineering
This presentation contains the basics of oscillators, types of oscillators & its mathematical Analysis. Numericals based on each type of oscillator are solved & given for practice.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
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Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
2. Objectives
Describe the basic concept of an oscillator
Discuss the basic principles of operation of an
oscillator
Analyze the operation of RC and LC oscillators
Describe the operation of the basic relaxation
oscillator circuits
3. Introduction
Oscillator is an electronic circuit that generates a
periodic waveform on its output without an external
signal source. It is used to convert dc to ac.
Oscillators are circuits that produce a continuous
signal of some type without the need of an input.
These signals serve a variety of purposes.
Communications systems,
digital systems (including computers), and
test equipment make use of oscillators
4. Introduction
An oscillator is a circuit that produces a repetitive signal from
a dc voltage.
The feedback oscillator relies on a positive feedback of the
output to maintain the oscillations.
The relaxation oscillator makes use of an RC timing circuit to
generate a nonsinusoidal signal such as square wave
Sine wave
Square wave
Sawtooth wave
6. Feedback Oscillator Principles
When switch at the amplifier input is open, no oscillation occurs.
Consider Vi,, results in Vo=AVi (after amplifier stage) and Vf = β(AVi)
(after feedback stage)
Feedback voltage Vf = β(AVi) where βA is called loop gain.
In order to maintain Vf = Vi , βA must be in the correct magnitude and
phase.
When the switch is closed and Vi is removed, the circuit will continue
operating since the feedback voltage is sufficient to drive the amplifier and
feedback circuit, resulting in proper input voltage to sustain the loop
Feedback circuit used as an oscillator
7. Basic principles for oscillation
An oscillator is an amplifier with positive feedback.
A
β
V e
V f
V s
V o
+
(1)fse VVV +=
(2)of βVV =
( ) ( ) (3)osfseo βVVAVVAAVV +=+==
8. Basic principles for oscillation
The closed loop gain is:
( ) ( )osfs
eo
βVVAVVA
AVV
+=+=
=
oso VAAVV β+=
( ) so AVVA =− β1
( )Aβ
A
V
V
A
s
o
f
−
=≡
1
9. Basic principles for oscillation
In general A and β are functions of frequency and
thus may be written as;
is known as loop gain
( ) ( ) ( )
( ) ( )sβsA1
sA
s
V
V
sA
s
o
f
−
==
( ) ( )sβsA
10. Basic principles for oscillation
Writing the loop gain becomes;
Replacing s with jω
and
( ) ( ) ( )ss βAsT =
( ) ( )
( )sT1
sA
sAf
−
=
( ) ( )
( )jωT1
jωA
jωAf
−
=
( ) ( ) ( )jωβjωAjωT =
11. Basic principles for oscillation
At a specific frequency f0
At this frequency, the closed loop gain;
will be infinite, i.e. the circuit will have finite output
for zero input signal - oscillation
( ) ( ) ( ) 1000 == jωβjωAjωT
( ) ( )
( ) ( )00
0
0
jωβjωA1
jωA
jωAf
−
=
12. Basic principles for oscillation
Thus, the condition for sinusoidal oscillation of
frequency f0 is;
This is known as Barkhausen criterion.
The frequency of oscillation is solely determined by
the phase characteristic of the feedback loop – the
loop oscillates at the frequency for which the phase
is zero.
( ) ( ) 100 =jωβjωA
13. Basic principles for oscillation
The feedback oscillator is widely used for
generation of sine wave signals.
The positive (in phase) feedback arrangement
maintains the oscillations.
The feedback gain must be kept to unity to keep the
output from distorting.
14. Basic principles for oscillation
In phase
Noninverting
amplifier
V f V o
A v
Feedback
circuit
15. Design Criteria for Oscillators
1. The magnitude of the loop gain must be unity or
slightly larger
– Barkhaussen criterion
2. Total phase shift,φ of the loop gain mus t be 0 ° or
360°
1=Aβ
16. RC Oscillators
RC feedback oscillators are generally limited to
frequencies of 1 MHz or less.
The types of RC oscillators that we will discuss are
the Wien-bridge and the phase-shift
18. Wien-bridge Oscillator
Working of Wein bridge Oscillator
The feedback signal in this oscillator circuit is connected to the non-inverting input
terminal so that the op-amp works as a non-inverting amplifier.
The condition of zero phase shift around the circuit is achieved by balancing the
bridge, zero phase shift is essential for sustained oscillations.
The frequency of oscillation is the resonant frequency of the balanced bridge and is
given by the expression fo = 1/2πRC
At resonant frequency ( ƒo), the inverting and non-inverting input voltages will be
equal and “in-phase” so that the negative feedback signal will be cancelled out by the
positive feedback causing the circuit to oscillate.
From the analysis of the circuit, it can be seen that the feedback factor β= 1/3 at the
frequency of oscillation. Therefore for sustained oscillation, the amplifier must have a
gain of 3 so that the loop gain becomes unity.
For an inverting amplifier the gain is set by the feedback resistor network Rf and Ri
and is given as the ratio -Rf/Ri.
19. Wien-bridge Oscillator
The loop gain for the oscillator is;
where;
and;
( ) ( ) ( )
+
+==
sp
p
ZZ
Z
R
R
sβsAsT
1
2
1
sRC
R
Z p
+
=
1
sC
sRC
Zs
+
=
1
21. Wien-bridge Oscillator
Since at the frequency of oscillation, T(jω) must be
real (for zero phase condition), the imaginary
component must be zero;
Which gives us;
0
1
0
0 =+
RCj
RCj
ω
ω
RC
1
0 =ω
22. Wien-bridge Oscillator
From the previous equation;
the magnitude condition is;
or
+=
3
1
11
1
2
R
R
( )
( )
++
+=
RC/jRCjR
R
jT
001
2
0
13
1
1
ωω
ω
2
1
2
=
R
R
To ensure oscillation, the ratio R2/R1 must be
slightly greater than 2.
23. Wien-bridge Oscillator
With the ratio;
then;
K = 3 ensures the loop gain of unity – oscillation
K > 3 : growing oscillations
K < 3 : decreasing oscillations
2
1
2
=
R
R
31
1
2
=+≡
R
R
K
24. Wien-bridge Oscillator
Design
The required frequency of oscillation
fo=1kHz
we have,
Take C=0.01µF, then R=1.6kΩ (Use 1.5kΩ
standard)
Gain of the amplifier section is given by,
Take Ri=1kΩ, then Rf=2.2kΩ
(Use 4.7kΩ Potentio meter for fine
corrections)
25. Phase-Shift Oscillator
C C C
R R
R
Rf
+
−
Vo0 V
Phase-shift oscillator
The phase shift oscillator utilizes three RC circuits to
provide 180º phase shift that when coupled with the 180º of
the op-amp itself provides the necessary feedback to
sustain oscillations.
26. The frequency for this type is similar to any RC circuit oscillator :
62
1
RC
f
π
=
where β = 1/29 and the phase-shift is 180o
For the loop gain βA to be greater than unity, the gain of the amplifier
stage must be greater than 29.
If we measure the phase-shift per RC section, each section would not
provide the same phase shift (although the overall phase shift is 180o
).
In order to obtain exactly 60o
phase shift for each of three stages,
emitter follower stages would be needed for each RC section.
The gain must be at least 29 to maintain the oscillation
28. If the gain around the loop equals 1, the circuit oscillates at this
frequency. Thus for the oscillations we want,
Putting s=jω and equating the real parts and imaginary parts,
we obtain
Phase-Shift Oscillator
29. From equation (1) ;
Substituting into equation (2) ;
# The gain must be at least 29 to maintain the oscillations.
Phase-Shift Oscillator
31. Phase Shift Oscillator – Practical
Design
Frequency of oscillation (F):
Gain of the Op Amp inverting amplifier (G):
Attenuation offered by the feedback RC
network is 1/29, so the gain of inverting
amplifier should be 29
Use Ri
=1.2 KΩ
So, Rf
=35KΩ
Use 50KΩ potentiometer and adjust its
value to obtain output on CRO
32. Phase Shift Oscillator – Practical
RC
fr
62
1
π
= 29
3
−=
−
=
R
R
K
f
The last R has been incorporated into the summing resistors
at the input of the inverting op-amp.
33. LC Oscillators
Use transistors and LC tuned circuits or crystals in
their feedback network.
For hundreds of kHz to hundreds of MHz frequency
range.
Examine Colpitts, Hartley and crystal oscillator.
34. Colpitts Oscillator
The Colpitts oscillator is a type
of oscillator that uses an LC
circuit in the feed-back loop.
The feedback network is made
up of a pair of tappedtapped
capacitorscapacitors (C(C11 and Cand C22)) and anan
inductor Linductor L to produce a
feedback necessary for
oscillations.
The output voltage is
developed across C1.
The feedback voltage is
developed across C2.
35. Colpitts Oscillator
KCL at the output node:
voltage divider produces:
substitute eq(2) into eq(1):
0
11
21
=
+
+++
sC
sL
V
Vg
R
V
sC
V o
gsm
oo
ogs V
sL
sC
sC
V •
+
=
2
2
1
1
( ) 0
1
1 12
2
2 =
++++ sC
R
LCssCgV mo
- Eq (1)
- Eq (2)
36. Colpitts Oscillator
Assume that oscillation has started, then Vo≠0
Let s=jω
both real & imaginary component must be zero
Imaginary component:
( ) 0
1
21
2
2
21
3
=
+++++
R
gCCs
R
LCs
CLCs m
( )[ ] 0
1
21
2
21
2
2
=−++
++ CLCCCj
R
LC
R
gm ωω
ω
+
=
21
21
1
CC
CC
L
oω
- Eq (3)
37. Colpitts Oscillator
both real & imaginary component must be zero
Imaginary component:
Combining Eq(3) and Eq(4):
to initiate oscillations spontaneously:
R
g
R
LC
m
12
2
+=
ω
Rg
C
C
m=
1
2
>
1
2
C
C
Rgm
- Eq (4)
38. Hartley Oscillator
The Hartley oscillator is
almost identical to the
Colpitts oscillator.
The primary difference
is that the feedback
network of the Hartley
oscillator uses tappedtapped
inductors (Linductors (L11 and Land L22)) and
a single capacitor Ca single capacitor C.
39. Hartley Oscillator
the analysis of Hartley oscillator is identical to that
Colpitts oscillator.
the frequency of oscillation:
( )CLL
o
21
1
+
=ω
40. Crystal Oscillator
Most communications and digital applications require the
use of oscillators with extremely stable outputextremely stable output. Crystal
oscillators are invented to overcome the output fluctuationoutput fluctuation
experienced by conventional oscillators.
Crystals used in electronic applications consist of a quartz
wafer held between two metal plates and housed in a a
package as shown in Fig. 9 (a) and (b).
41. Crystal Oscillator
Piezoelectric Effect
The quartz crystal is made of silicon oxide (SiO2) and
exhibits a property called the piezoelectricpiezoelectric
When a changing an alternating voltage is applied across
the crystal, it vibrates at the frequency of the applied
voltage. In the other word, the frequency of the applied ac
voltage is equal to the natural resonant frequency of the
crystal.
The thinner the crystal, higher its frequency of vibration.
This phenomenon is called piezoelectric effect.
42. Crystal Oscillator
Characteristic of Quartz
Crystal
The crystal can have two resonant
frequencies;
One is the series resonance frequency f1
which occurs when XL = XC. At this
frequency, crystal offers a very low
impedance to the external circuit where
Z = R.
The other is the parallel resonance (or
antiresonance) frequency f2 which
occurs when reactance of the series leg
equals the reactance of CM. At this
frequency, crystal offers a very high
impedance to the external circuit
R
L
C
CM
43. Crystal Oscillator
The crystal is connected as a series element in the
feedback path from collector to the base so that it is
excited in the series-resonance mode
BJT
FET
44. Crystal Oscillator
Since, in series resonance, crystal impedance is the smallest that
causes the crystal provides the largest positive feedback.
Resistors R1, R2, and REprovide a voltage-divider stabilized dc bias
circuit. Capacitor CE provides ac bypass of the emitter resistor, RE to
avoid degeneration.
The RFC coil provides dc collector load and also prevents any ac
signal from entering the dc supply.
The coupling capacitor CC has negligible reactance at circuit
operating frequency but blocks any dc flow between collector and
base.
The oscillation frequency equals the series-resonance frequency of
the crystal and is given by:
C
o
LC
f
π2
1
=
45. Unijunction Oscillator
The unijunction transistor
can be used in what is
called a relaxation oscillatorrelaxation oscillator
as shown by basic circuit as
follow.
The unijunction oscillator
provides a pulse signal
suitable for digital-circuit
applications.
Resistor RT and capacitor CT
are the timing components
that set the circuit
oscillating rate
UJT
46. Unijunction Oscillator
Sawtooth wave
appears at the emitter
of the transistor.
This wave shows the
gradual increase of
capacitor voltage
47. Unijunction Oscillator
The oscillating frequency is calculated as follows:
where, η = the unijunction transistor intrinsic stand-
off ratio
Typically, a unijunction transistor has a stand-off
ratio from 0.4 to 0.6
( )[ ]η−
≅
1/1ln
1
TT
o
CR
f