Automatic night Street lamp proposal , circuit diagram ,description ,report

INTRODUCTION:

 The street light will be on when night  falls and it will automatically be on and if the morning comes it will automatically becomes of. I have used LDR in this project without using micro controller.

The circuit diagram present here is that of a street light that automatically switches ON when the night falls and turns OFF when the sun rises. In fact you can this circuit for implementing any type of automatic night light.

The circuit uses a Light Dependent Resistor (LDR) to sense the light .When there is light the resistance of LDR will be low. So the voltage drop across POT R2 will be high.This keeps the transistor Q1 ON. The collector of Q1(BC107) is coupled to base of Q2(SL100). So Q2 will be OFF and so do the relay. The bulb will remain OFF.

When night falls the resistance of  LDR increases to make the voltage across the POT R2 to decrease below 0.6V. This makes transistor Q1 OFF which in turn makes Q2 ON. The relay will be energized and the bulb will glow.

Circuit diagram with Parts list.

Notes.

• POT R2 can be used to adjust the sensitivity of the circuit.
• You can use bulb of any wattage, provided that relay should have the sufficient rating.
• The circuit can be powered from a regulated 9V DC power supply.
•  to get the power supply circuit for this project.
• The relay K1 can be a 9V SPDT relay.

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.

In the project we use light detecting resistor as a light sensor & a NAND gate for detection of high level or low level of voltage to energize the RELAY coil which is used to interface the control circuit with the external light source.

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.

By means of this circuit we can control any other electrical appliances as we use the double pole double throw relay switch.

Again for economic operation it is very much helpful and it is very much easy and cheap to make the circuit for house hold purposes.
 

The operation and operating characteristics of the components which are used in the circuits are briefly outlined below-

LDR

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.

The figure above  shows that when the torch is turned on, the resistance of the LDR falls,allowing current to pass through it.

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).

 Circuit diagram

2nd report