Introduction: INTRODUCTION:

Automatic night light control system needs no manual operation for switching ON and OFF when there is need of light. It detects itself whether there is need for light or not. When darkness rises to a certain value then automatically light is switched ON and when there is other source of light i.e. day time, the light gets OFF.

Wastage of power is not desirable in any system. So it is very much economic to have this arrangement so that power is not wasted during day time where manual operation is not possible. Though we can use it in our daily life also for the betterment of our system.

While dealing with this project we faced a problem that the light remained on or off depending upon the presence of any other light source. If we want to make the light off in night hours when there is no need of light, or after switching off the light if we want to make the light on again it was not possible with the circuit investigated earlier. As we don’t want any manual operation we have an arrangement of doing this by means of sound (like clapping sound).This mechanism makes the circuit is more flexible.

Step 1: Things Required:

1) 555 timer IC

2) Photodetector(LDR)

3)1000ohms resistor

4)500ohms resistor


6)On/Of Switch

7) 9v Battery Holder

8) 9v Battery Holder


Step 2:

LDRs or Light Dependent Resistors are very useful especially in light/dark sensor circuits. Normally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms, but when they are illuminated with light resistance drops drastically.
When a light level of 1000 lux (bright light) is directed towards it, the resistance is 400 (ohms).
When a light level of 10 lux (very low light level) is directed towards it, the resistance has
risen dramatically to 10.43M (10430000 ohms).

555 timer IC
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.
Introduced in 1971 by Signetics, the 555 is still in widespread use due to its ease of use, low price, and stability. It is now made by many companies in the original bipolar and also in low-power CMOS types. As of 2003, it was estimated that 1 billion units are manufactured every year

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