Automatic headlight circuit help

Discussion in 'The Projects Forum' started by stephen_c, Oct 1, 2008.

  1. stephen_c

    Thread Starter New Member

    Oct 1, 2008
    4
    0
    First post here glad i found the site. :cool:

    I need a little help designing a circuit. What im trying to do is make automatic headlights for my car. The thing is i want it on a delay so if i drive under a overpass my headlights dont turn off and back on. I have a HID retrofit and dont want to damage the ballast. I have the delay part down i think but im not sure what to use as the light sensor. i would like to keep it as simple as possible.

    this is the delay circuit i plan on using:
    [​IMG]

    I dont know enough about photo sensors to know which one will work best.


    Thanks for any help.
     
  2. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
    68
    Are you looking to turn them on when dark/dusk or off at dawn/light?
     
  3. stephen_c

    Thread Starter New Member

    Oct 1, 2008
    4
    0
    I want them to come on when it gets dark.
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    I suggest replacing the rectifier diode with a photodiode, and reconfiguring the transistor as a common emitter. You'll have a few seconds of delay before the lights come on when starting the car at night, but the system should otherwise perform to your satisfaction.
     
  5. stephen_c

    Thread Starter New Member

    Oct 1, 2008
    4
    0
    I think i just decided to use this circuit...
    [​IMG]
    then you the output that would go to the relay in that circuit to power the delay circuit.

    I ordered all the parts tonight except for a 7.5k resistor which i will get at school. :)
     
  6. dcorwin822

    New Member

    May 13, 2009
    2
    0

    Hi, New here but how did this circuit work out for you? Got any more details on how it worked out for ya? What spec photo resistor did you end up using?
     
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