Automatic Headlight Brightness Switch


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Driving the highway with your high-beam headlights can really increase your visibility, but can be 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


Schematic for Automatic Headlight Brightness Switch

Parts

Part
Total Qty.
Description
Substitutions
R115K 1/4W Resistor
R2, R3, R435K Pot
Q11NPN Phototransistor
Q212N3906 PNP Transistor
K11Low Current 12V SPST Relay
K21High Current 12V SPDT Relay
S11SPST Switch
B11Car Battery
MISC1Case, 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.

Related Circuits

Automatic Headlight Brightness Switch, Wireless Auto Tachometer, Car Alarm Arming Horn Beep Canceller

Comments

Steve
Automatic Headlight Brightness Switch
Thursday, January 24, 2008 5:05:27 AM
Guten tag.I am germany student, I like your circuit yes, if you email please me information how it work. i do this for school and i like cars, sexytime please danke kiss kiss
dhanu
Automatic Headlight Brightness Switch
Wednesday, January 23, 2008 9:35:23 AM
i really like this project ... could i know about the detail descriptions of the circuit and the cost of this project???????? thank uuuuuu...
Zeberdy
Automatic Headlight Brightness Switch
Thursday, January 17, 2008 9:26:16 AM
Yooo dis is well elpful i is gunna use it az me projec if youse can gis some more info like i wud much appreciate it aite. much loves. keep it reals Zebby xxooxx
jon dom
Automatic Headlight Brightness Switch
Thursday, January 10, 2008 8:56:25 AM
aaaaaaaaaaaaaye mate! kin waaaaaaaa this project is mint like it'd be reeet sound if ya could let me knows about some more info like i iz doing it for me project its sound! cannie wait kid hit me back inabit mert(Y)
jain
Automatic Headlight Brightness Switch
Thursday, January 10, 2008 5:29:13 AM
can u tell the minimum budget for this project
INGOSI
Automatic Headlight Brightness Switch
Sunday, December 16, 2007 6:21:35 AM
tell me more about the phototransistor (The specifications/characteristics) via my E mail
loet
Automatic Headlight Brightness Switch
Wednesday, December 12, 2007 12:43:06 PM
i really loved the design, its ballistic i would like work on it as my project but i'm having trouble with th 2 relays, can i replace the whole relay unit with one? also what if i want to use the darlington pair, may u advise me about how i would change the circuit. thanx
uday
Automatic Headlight Brightness Switch
Thursday, November 29, 2007 2:37:22 AM
where can i get the equipments for this project and what is the overall cost of the project
carlos
Automatic Headlight Brightness Switch
Friday, November 16, 2007 11:45:10 PM
where can i buy all the parts for this projects?

(Editor's notes: Electronics store.)

wubantos
Automatic Headlight Brightness Switch
Thursday, November 15, 2007 11:57:31 AM
i really like the circuit so if don't mind i really want to use it for my project so send me more detailt via my mail. thanks a lot
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