The document describes an automatic street light controller circuit using a light-dependent resistor (LDR) and relay for efficient operation. It details the working process, advantages like energy savings and low cost, and disadvantages such as power limitations and maintenance needs. The conclusion emphasizes the potential benefits of this system for electricity conservation.

1. Street Lamp Working Process
Submitted by:
Md. Ziaul Haque
Id: 555181028
Semester: 4th
Department: EEE
Submitted to:
Md. Salim Raza
Assistant professor,
Department of EEE
Hamdard University Bangladesh
1

2. Index……
Introduction
Required Elements
1. Comparator, 2. LDR & 3. Relay
Equivalent Circuit
Working process
Advantage & Disadvantage
Conclusion
2

3. Introduction
There are several ways to turn on the street
lights but here we describes an Automatic
Street Light Controller Circuit that uses LDR
and Relay to perform this job automatically.
3

4. Comparator
A comparator is a device which compares the two analog inputs and gives the digital
output depending upon which input is higher.
Comparators are of two types :
1. Inverting and
2.Non-inverting
For non-inverting comparator-
Vo = 1, if V+ > V-
=0, if V+ < V-
4

5. LDR
oLDR means Light Dependent Resistor
oAn LDR is a component that has a (variable) resistance that changes with the light
intensity that falls upon it.
o0 ohm (in light)
∞ (in dark)
5

6. Relay
A relay is an electrically operated switch.
The input circuit is switched off and no
current flows through it until something
turns it on. The output circuit is also switched off.
When a small current flows in the input circuit,
it activates the electromagnet, which produces a
magnetic field all around it.
6

7. Continue……
7
The energized electromagnet pulls the metal
bar in the output circuit toward it, closing the
switch and allowing a much bigger current to
flow through the output circuit.
The output circuit operates a high-current
appliance such as a lamp or an electric motor.

8. Equivalent circuit
8

9. Working process
The main part of this circuit is the LDR .
 It offers low resistance in light. For this LDR acts like short and in comparator V+ < V- ,
that’s why lamp will turn off.
 It offers high resistance in dark. For this LDR acts like open and in comparator V+ > V- ,
that’s why lamp will turn on.
9

10. Advantage & Disadvantage
Advantage
Energy saving
Low cost
Safe and secure
Automated operation
Disadvantage
It has a limitation of power
Light turns on when shadow falls on LDR
Rechargeable batteries of the automatic
street light system are required to be
replaced a few times.
10

11. Conclusion…..
In coming days, this will prove a great benefit to the country, since it will save a lot of
electricity of power plant that gets wasted in illuminating the street light.
Using this process we can make such equipment automated.
11

12. 12
Thank You All