Schematics > Automotive > Automatic Headlight Brightness Switch
Automatic Headlight Brightness SwitchDriving the highway with your high-beam headlights can really increase your
visibility, but can he a blinding hazard for other drivers. This simple circuit
can be wired into your headlight switch to provide automatic switching between
high and low beam headlights when there is oncoming traffic. It does this by
sensing the lights of that traffic. In this way, you can drive safely with your
high-beams on without blinding other drivers.
Schematic
Parts:
| Part |
Total Qty. |
Description |
Substitutions |
| R1 |
1 |
5K 1/4W Resistor |
|
| R2, R3, R4 |
3 |
5K Pot |
|
| Q1 |
1 |
NPN Phototransistor |
|
| Q2 |
1 |
2N3906 PNP Transistor |
|
| K1 |
1 |
Low Current 12V SPST Relay |
|
| K2 |
1 |
High Current 12V SPDT Relay |
|
| S1 |
1 |
SPST Switch |
|
| B1 |
1 |
Car Battery |
|
| MISC |
1 |
Case, wire, board, knobs for pots |
|
Notes:
1. Q1 should me mounted in such a way so it points toward the front of the
car with a clear line of site. Suitable places are on the dashboard, in the
front grill, etc.
2. Adjust all the pots for proper response by testing on a deserted road.
3. S1 enables and disables the circuit.
4. B1 is, obviously, in the car already.
5. Before you try to connect this circuit, get a wiring diagram for your car.
Some auto manufacturers do weird things with wiring.
6. Connection A goes to the high beam circuit, B goes to the headlight switch
common and C connects to the low beam circuit.
Title: Automatic Headlight Brightness Switch
Source: www.electronics-lab.com
Published on: 2005-02-02
Reads: 761
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