This document presents a project to design a variable DC voltage supplier with segment display. The project objectives are to design a circuit that can supply adjustable output voltage from 0-30V and fixed 5V, with maximum input of 220V AC and 3A. The components used include a transformer, diodes, capacitors, regulators, and display. Some problems encountered were unavailable transformer and voltage/current output restrictions. The project aims to develop an electrical device to supply variable DC voltage for laboratory and commercial applications.

1. PRESENTED BY :
Divya Mishra (21039)
Rupa Rokaya (21022)
Manish Karn (21035)
Sujeet Kumar Jha (21009)
Ahmed raja khan (21432)
KATHMANDU UNIVERSITY
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
Variable DC Voltage Supplier
with Segment Display
PRESENTED TO :
DOEEE

2. INTRODUCTION
Background and features
•The DC Voltage supplier is an electrical device
which supply DC output with visual indication.
•It is capable of supplying constant as well as
variable dual voltages and currents to the user.
•It is small, simple, cheap and efficient device
that is performing efficient functions.

3. OBJECTIVES
•Our objectives is to design the electronic circuit
and apply it in way that it meets the following
technical specification.
•Input voltage :- 220 v Main AC
•Input Current :- 3A (Max)
•Output Voltage :- 0 – 30v adjustable , 5v fixed
•Output current :- 2mA – 3A, 1A fixed
•Complete protection of the device against the
loads and malfunction.

4. COMPONENTS
•Transformer
•Diode
•Electrolytic Capacitors
•Regulators
•Potentiometer
•Fuse
•Output connector
•Segment Display

5. WORK ACCOMPLISHED
•Transformer is connected to ac main and stepdown is
done.
•Stepdown voltage is rectified to pulsating dc voltage.
•Pulsating dc voltage is smoothened by using
electrolytic capacitor.
•LM 317 and LM 7805 is studied and tested in
breadboard.

6. PROBLEMS ENCOUNTERED
•Unavailability of expected transformer.
•Voltage is restricted to 1.27V rather of 0V.
•Current output is restricted to 1.5A rather
expected is 3A.

7. APPLICATIONS
•Laboratory
•Electrical and electronics Projects
•Home appliance
•Commercial Use

8. BLOCK DIAGRAM
• 220 v
AC INPUT
STEP DOWN
Transformer
RECITIFICATION
Diodes
FILTERING
Capacitors
FIXED
Regulator
VARIABLE
Regulator
5v Dc
Output
0- 30 V
DC Output
Segment
Display

9. GANTT CHART
TASK Sept. 2014 November
2014
December
2014
January –
March 2014
March 2015 June 2015 July 2015
Study of possible
project
Project Title
Selection
Literature Review
Proposal Writing
and Defense
Circuit design and
implementation of
circuit
Mid Term
Hardware and PCB
Development
Testing and
Evaluation of the
system
Work Accomplished
Work Remaining

10. CONCLUSION
• We thank Department of Electrical and Electronics in
providing us the opportunity to get engaged in project
works which will help us to explore our creativity and
knowledge. Our team aim is to develop an electrical
device i.e. variable DC voltage supplier. We completed
our project to some extent and encountered some
problems while testing components as mentioned
above. We are trying to overcome these problems and
hope for completion of our project in stipulated time.

11. REFRENCES
•www.wikihow.com/Make-an-AC-DC-Converter
•www.Wikipedia.com
•John Palmisano, “ Electronics Components And
Hardware I (CFS)” , part 1 & 2
•Sedra & Smith, Microelectronic Circuits, CBS
College Publishing, USA, 1987