Pulse Generator with Adjustable duty cycle
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Transcript of Pulse Generator with Adjustable duty cycle
May 2015
Electronics & Communication Engineering
Semester 6
Indus University
Pulse Generator with Adjustable Duty Cycle
Project members:
Mitwa Palkhiwala(IU1241090028)
Ami Goswami(IU1241090014)
Project guide:
Prof. Hansa Shinghrakhia
CERTIFICATE
This is to certify that the project entitled “Pulse Generator with Variable Duty Cycle” is a bonafied report of the work carried out by MitwaPalkhiwalaand Ami Goswamias a part of subject: Mini Project-II of semester 6
of the degree of Bachelor of Technology in Electronic And Communication Engineering at Indus Institute of Technology & Engineering, Indus University, Ahmedabad, Gujarat.
Project Guide:
Prof. HansaShinghrakhia
Department Of Electronics and Communication Engineering
Indus University, Ahmedabad
Prof. R N Mutagi
Head of Department
Department Of Electronics and Communication Engineering
Indus University, Ahmedabad
ACKNOWLEDGEMENT
“Success can be achieved only by hard work and proper guidance.”
For the successful completion of our project, we would like to express our sincere gratitude to INDUS
UNIVERSITY, AHMEDABAD for providing us an environment for doing this practical work.
We thank Mrs. HansaShinghrakhia, Professor, Electronics and Communication Engineering Department,
Indus University for providing seamless support and knowledge over the past one semester, and also for
providing right suggestions at every phase of the development of our project. We sincerely thank them for their
extensive support, guidance and helping us put our ideas to work and providing us the conducive environment
for carrying through our academic schedules and projects with ease.
We are grateful to Prof. R N Mutagi, Head of Electronics and communication Engineering Department, IITE
for his useful inputs at every stage of our project throughout our academic schedules.
Last but not the least, we bow down our head to the ALMIGHTY GOD, without whose blessings this work
would not have turned into reality.
MitwaPalkhiwala(IU1241090028)
Ami Goswami(IU1241090014)
Semester 6, B.Tech,Electronics and Communication Engineering,Indus University
Table of content
Sr. No. Title Page No.
1. 0 Introduction
2. 0 Circuit design
3.0 Simulation and outputs
4. 0 Application
5. 0 Conclusions
6. 0 References
1. Introduction An electronic circuit capable of producing a waveform that rises abruptly, maintains a relatively flat top
for an extremely short interval, and then rapidly falls to zero i.e circuits whose exclusive function is
generating short duration, rectangular waveforms are usually specifically identified as pulse generators.
The term pulse generator is often applied not only to an electronic circuit generating prescribed pulse
sequences but to an electronic instrument designed to generate sequences of pulses with variable delays,
pulse widths, and pulse train combinations, programmable in a predetermined manner, often
microprocessor-controlled.
In this project, we are going to design a pulse generator having adjustable duty cycle. Duty cycle is
nothing but the percentage of one period in which a signal is active. User may set the duty cycle as per
their requirements.
Pulse
Generator
2. Circuit design
Important formulae:
% duty cycle = Ra+Rb
Ra+2 Rb×100 %
Charging time tc = 0.693(Ra + Rb)C
Discharging time, td = 0.693(Rb)C
Total time , t = 0693(Ra + 2Rb)C
A1
555_VIRTUALGND
DIS
OUTRST
VCC
THR
CON
TRI
D1
1N4148D2
1N4148
Rb1
1MΩKey=A
50%Rb2
6.5kΩC1µF
VCC9V
Ra 6kΩ
XSC1
A B
Ext Trig+
+
_
_ + _
C10.05µF
Calculations:
Let F = 1.3 Hz = >t = 1F
=> t = 792.910 ms
Let C = 1 µF and Ra= 6KΩ
For 30% duty cycle, tc = 0.3t and td = 0.7t
td = 0.693(Rb)C=0.7t Rb = 800KΩ
For 50% duty cycle, tc = 0.5t and td = 0.5t
td = 0.693(Rb)C=0.5t Rb = 572.08KΩ
For 70% duty cycle, tc = 0.7t and td = 0.3t
td = 0.693(Rb)C=0.3t Rb = 343.25KΩ
Component list:
Component Quantity SpecificationsResistors 2 Ra = 6KΏ
Rb2 = 6.5KΏPotentiometer 1 Rb1 = 1MΏCapacitors 2 C = 1µF
C2 = 0.05µFDiodes 2 D1 = 1N4148
D2 = 1N4148Power Supply 1 Vcc = 9VIC 1 NE555
3. Simulation and outputs:
Total time period A1
555_VIRTUALGND
DIS
OUTRST
VCC
THR
CON
TRI
D1
1N4148D2
1N4148
Rb1
1MΩKey=A
50%Rb2
6.5kΩC1µF
VCC9V
Ra 6kΩ
XSC1
A B
Ext Trig+
+
_
_ + _
C10.05µF
30% duty cycle
70% duty cycle
DSO OUTPUT 1
DSO OUTPUT 2
DSO OUTPUT 2
4. Applications:
Pulses can be injected into a device that is under test and used as a stimulus or clock signal or analyzed,
confirming the proper operation of the device or pinpointing a fault in the device.
Pulse generators are also used to drive devices such as switches, lasers and optical components,
modulators, intensifiers as well as resistive loads.
The output of a pulse generator may also be used as the modulation signal for a signal generator. Non-
electronic applications include those in material science, medical, physics and chemistry.
5. Conclusion:
Thus, our objective of making a pulse generator with adjustable duty cycle has been achieved.
As the wiper of potentiometer of 1 MΩ is moved from one end to other, any desired percentage of duty cycle between 0% to 100% can be obtained .
6. References:Books;
Ramakant A. Gayakwad ,”Op-Amps and Linear Integrated Circuits” , Fourth Edition, PHI Publications
David A. Bell , “Operational amplifiers and linear IC’s” , Third Edition, Oxford University Press.
Web Sites ; http://www.learnabout-electronics.org/Oscillators/osc44.php