Thursday, September 4, 2014

Automatic headlight dim switch


With this cool schema integrated to your cars headlight system , you can drive cool headed in high beam.The schema will take over the duty of low beaming the headlight when vehicles approach against , and high beams the lights when they pass over.









The schema is based on a photo transistor(Q1) for sensing the approaching vehicles and transistor Q2 (BC177) for switching the relays for controlling the headlight.When the light from the opposite vehicle falls on Q2 , it’s collector current increases and turns ON Q1.The relay will be activated and the head light will be dimmed.When the vehicle pass over the reverse will happen.



Notes.

* The battery B1 can be the 12V car battery itself.
* Adjust POT’s R1,R2,R4 to obtain optimum performance.
* The Q1 can be any general purpose PNP photo transistor.It should be mounted in front of the car so that the light from opposite vehicle easily falls on it.
* Relay contact A goes to high beam schema,B to low beam schema and C is the common point.
* Carefully understand the wiring of your car before attempting to install the schema.Wrong connections could easily bring trouble to your cars wiring.


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