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1. ON/OFF CONTROL OF ARTIFICIAL LIGHTS BASED ON
SUNLIGHT AVAILIBILITY
Prepared under the guidance of
Mr. MousamGhosh
(Assistant professor EEE dept.)
BY:-
Manish Kumar Singh
Amit Kumar Meena
Avinash Kumar

2. CONTENTS
 Introduction
 Circuit Diagram
 Isolated regulated power supply (5V-12V)
 What is Power Supply Isolation?
 Main Purposes of Power Supply Isolation
1)Safety
2)Voltage Level Shifting
3)Obtaining Multiple Output Converters
4)Ground Loop Prevention
 555 timer used in its comparator mode
 Switching control using transistor
 The main controlling components used in circuit
1)Special Light detecting resistors
2)Relay

3. INTRODUCTION
 The circuit that we have designed controls the amount
of artificial light in a room, based on its brightness,
occupancy, and sometimes other factors.
The project can be divided into three basic parts:-
1.Isolated Power Supply
2.Comparator using 555 timer
3.Switching circuit using transistor

4. CIRCUIT DIAGRAM

5. ISOLATED REGULATED POWER SUPPLY
 Isolated regulated power supply is an electronic circuit
that is designed to provide a constant dc voltage of
predetermined value across load terminals irrespective
of ac mains fluctuations or load variations.

6. ISOLATED REGULATED POWER SUPPLY
What is Power Supply Isolation?
In the context of power supply design, isolation is the
electrical and sometimes magnetic separation between
two circuits in close proximity to each other.
Main Purposes of Power Supply Isolation
 Safety
 Voltage Level Shifting
 Obtaining Multiple Output Converters
 Ground Loop Prevention

7. 555 timer used in its comparator mode
 The 555 timer IC is an integrated circuit (chip) used in a
variety of timer, pulse generation,
and oscillator applications. The 555 can be used to provide
time delays, as an oscillator, and as a flip-flop element.
Derivatives provide up to four timing circuits in one
package.

8. 555 timer used in its comparator mode
The cicuit diagram that we have used in our project is
shown below :-

9. Switching control using transistor
The difference this time is that to operate the transistor as a switch
the transistor needs to be turned either fully “OFF” (cut-off ) or
fully “ON” (saturated). An ideal transistor switch would have
infinite circuit resistance between the Collector and Emitter when
turned “fully-OFF” resulting in zero current flowing through it
and zero resistance between the Collector and Emitter when
turned “fully-ON”, resulting in maximum current flow.

10. Main controlling components used in circuit
(1)LDR (Light detecting resistors):-
LDRs (Light detecting resistors) will, as the name suggests, switch
according to the ambient light levels irrespective of the time of day or
when the sun officially rises or sets.

11. Main controlling components used in circuit
(2)Relay :-
A relay is an electrically operated switch Many relays use
an electromagnet to mechanically operate a switch, but
other operating principles are also used, such as solid-state
relays

12. Hysteresis Loop
The hysteresis loop can be defined as the difference
between the intensity of light required for
switching(ON/OFF) of the artificial light. Suppose the
natural light is getting closer to the LDR at an instant the
artificial light gets turned on, now suppose the natural light
is getting farther from the LDR now the artificial light will
turn off at another instant. So, the difference between this
two intensities of light is called hysteresis loop. The two
different intensity level of light is required for switching on
and off the artificial light. The intensity of light required for
switching on and off the artificial light can be controlled by
the potential divider.

13. Thank you