The document is a project report on a non-contact AC voltage detector submitted for a diploma in electrical engineering at Saroj Mohan Institute of Technology. It outlines the abstract, required tools, circuit diagram, components, construction, working principles, and safety cautions associated with the device. The project emphasizes the importance of safety when working with electricity and provides instructions for building a DIY voltage detector that offers an alert system using a buzzer and LED.

1. SAROJ MOHAN INSTITUTE OF TECHNOLOGY
PROJECT REPORT
ON
Non-contact AC Voltage Detector.
SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD
OF
THE DEGREE OF
DIPLOMA
(Electrical Engineering)
SUBMITTED TO
SAROJ MOHAN INSTITUTE OF TECHNOLOGY, GUPTIPARA
SUBMITTED BY
NAME:
ROLL:
NO:
GUIDED BY
MR.MALAY GHATA
LECTURER
(Electronics & Telecommunication Department)
May 2019

2. INDEX
SL. NO. CONTENT PAGE NO.
01 ACKNOWLEDGEMENT 01
02 ABSTRACT 02
03 REQUIRED TOOL 03
04 CIRCUIT DIAGRAM 04
05 COMPONENTS REQUIRED 05
06 CONSTRUCTION & WORKING 06
07 CAUTION & REFFERENCE 07
08 PREPARED BY 08

3. ACKNOWLEDGEMENT
I would like to place on record my deep sense of gratitude to Prof. Malay Ghata,
HOD-Dept. of Electronics & Telecommunication Engineering, SMIT, Guptipara,
for his generous guidance, help and useful suggestions.
I express my sincere gratitude to Prof. Abhisek Ganguly,(HOD) Dept. of Electrical
Engineering, SMIT, Guptipara, for his stimulating guidance, continuous
encouragement and supervision throughout the course of present work.
I also wish to extend my thanks to Prof. Sourav Adhya and other colleagues for
attending my seminars and for their insightful comments and constructive
suggestions to improve the quality of this project work.
I am extremely thankful to Kajol Sarkar , Director, SMIT, Guptipara for providing
me infrastructural facilities to work in, without which this work would not have
been possible.
Signature(s) of Students

4. ABSTRACT
Electricity can cause serious injury or even death which is why safety must come
first when working with electricity or electrical devices. In order to avoid injury,
prior to starting work on an electrical box such as an AC mains switch-board or
a power supply, for example, you must first verify there is no AC voltage. If you
can't completely isolate your device from the supply wires, how can you be sure
that there's no voltage remaining? Enter a non-contact AC voltage detector.
There are several options available on the market and they range in price, but in
true DIY fashion, with this kit you are able to quickly and easily create your own
non-contact AC voltage detector in less than an hour.

5. Required Tools
1. Soldering Iron
2. Solder
3. Drill and drill bits (for making holes in the box)
4. Copper Wire
5. Cutters (for copper wire)
6. Adhesive Tape

6. CIRCUIT DIAGRAM
T1,T2,T3=BC 547(NPN)

7. COMPONENTS REQUIRED
Qty. Part Description
3 Transistors BC 547(NPN)
1 Resistor 1.0 MΩ
1 Resistor 100KΩ
1 Resistor 200Ω
1 LED, Red
1 Buzzer 9V
1 Switch
1 9V Battery
1 Battery Snap
1 Case

8. Construction & Working
Main part of this simple AC voltage detector is transistor, it acts as a amplifier and switch,
Buzzer produce sound alert when the wire spiral detects the EMF (electro magnetic field) on AC
supply carrying wire, LED also glows to indicate the AC supply detection.
BC 547 Transistor
It is a general purpose NPN bipolar junction transistor, it has three terminals called collector,
base, emitter. This transistor widely used in amplification, switching and other active
applications.
In this circuit three stage constructed with BC547, transistor Q3 base is connected with wire
spiral and it will detect EMF on the AC supply carrying wire, and signal from Q3 transistor is
given to the Q2 transistor base, this Q2 gets large bias than Q3 and so it can amplify the input
signal and gives to the Q1 transistor base, here the Q1 transistor acts as a switch and when signal
reach its base it becomes closed switch and connects buzzer, LED with bias, if no signal then Q1
stays in off condition.

9. CAUTION
For this circuit we can use small Copper plate or Wire spiral as a EMF detector, the wire spiral can be made
from 15cm insulated wire. Should not touch the spiral wire or bare hand on the AC supply carrying wire, Be
extremely care when you handle high volt AC supply.
REFFERENCE
1. HELP FROM PROJECT GUIDE
2. http://www.theorycircuit.com/non-contact-ac-voltage-detector-
circuit/
3. https://www.jameco.com/Jameco/workshop/jamecofavorites/non-
contact-AC-voltage-detector.html

10. PREPARED BY
PRASENJIT SAMANTA
GUIDED BY: Mr. Malay Ghata