Automated Car Lightning System

Summary:

In an effort to improve road safety Government has rolled out a new regulation as per which, if a vehicle is approaching from the opposite side, one is required to dim out the headlights so that it doesn’t cause any trouble to the driver who is approaching from the other side. This would help in avoiding a lot of accidents.

However, if this dimming and brightening of headlights is made an automatic function then it could help to ensure a safe drive as well as a convenient driving experience.

Description:

Block diagram:

Fig. 1: Block Diagram of Automatic Car Headlights

Description:

LDR sensor:

LDR stands for Light Dependant Resistor. It acts as a variable resistor whose resistance changes with the intensity of light..When the light intensity increases, the resistance offered by the sensor decreases and vice versa.

Typical Image of Light Dependant Resistor (LDR) used as Light Sensor in the circuit

Fig. 2: Typical Image of Light Dependant Resistor (LDR) used as Light Sensor in the circuit

Circuits and Working

Sensing Circuit

This is made to work as a switch making transistor to operate in saturation and cut off region. Here LDR provides necessary bias to the transistor.

Components used:

1)LDR sensor

2)60kohm resistor

3)IRFZ44N transistor (or any n channel MOSFET)

4)relay

5)connecting wires

6)supply 12V from car batteries

All componenets are self explanatory.

I have preferred IRFZ44N because of high current and good heat dissipation capability.

Relay :

Typical Image of Relay used for switching Headlights

Fig. 3: Typical Image of Relay used for switching Headlights

This has NC (normally Closed) & NO (Normally Opened) contacts.

Out of this, “NC” contact is used where bright light of the headlight is connected.

“NO” contact is used where dim light of the headlight is connected.

Reason is explained after circuit diagram’s description.

CIRCUIT DIAGRAM:

There are two headlights, one is dim another is bright. If you cannot distinguish well between these then you may ask the garage people to fix that as there are different arrangements for different cars.

The LDR should be exposed to light hence it must be placed in a way that the lights of the opposite car approaching you must fall on the LDR and not on your own car’s lights.

Although resistor 30K suits for my circuit, one may take exact MOSFET. Due to manufacturing process one transistor cannot be exactly identical to the other (their beta value may change).Hence 30K value cannot be assured for your circuit so make adjustments such that transistor acts as a switch for the considered resistor values.

Working:

When light shines on LDR its resistance decreases and hence bias voltage of the MOSFET increases turning it on and hence relay status changeover takes place from NC TO NO. As there is dim bulb connected to NO it turns on. Similarly as the car passes by, light ceases to fall on LDR and hence its resistance increases which causes a lower Vbe MOSFET voltage thereby switching off the transistor. Relay status changeover takes place from NO to NC and thus bright bulb switches are turned on.

Prototype of Relay Circuit soldered on a PCB for automatic controlling of car headlights