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Dimmer switch on fogs

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  • 21-06-2014 3:53pm
    #1
    rcanpolat
    Registered Users Posts: 146 ✭✭


    So I have a civic and it came with these fog lights (aftermarket JDM style) that the last dude put into the car. I like them but I find the light is very strong coming off them.

    So...

    Is it possible for me to wire up a potentiometer to them to reduce the amount of juice flowing into the lights making them dimmer?

    Im fine with soldering etc but I don't know really know too much about electronics. I'm worried about wiring one up... With 12v flowing through it and god knows what current could it heat up and melt my center console in the car?

    My only experience with potentiometers is rewiring my electric guitars and their volume and tone pots. I've never dealt with direct current in a potentiometer.

    Any suggestions?


Comments

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    #2
    gctest50
    Registered Users Posts: 9,605 ✭✭✭gctest50


    An ordinary potentiometer like in your guitars would melt

    If the fog lights are plastic (ie not grounded ) you could wire them in series instead


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    #3
    visual
    Closed Accounts Posts: 3,268 ✭✭✭visual


    Change the bulb to the desired wattage is the simple solution.


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    #4
    rcanpolat
    Registered Users Posts: 146 ✭✭rcanpolat


    my fogs are metal so they are grounded. would you know what kind of potentiometer i would need?

    i would change the bulb to a lower wattage but the day i run into thick fog i would like to be able to boost the light for better cut through


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    #5
    colm_mcm
    Registered Users Posts: 73,382 ✭✭✭✭colm_mcm


    But surely if you use them only when there is fog, and not when there isn't fog there is no issue?


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    #6
    gctest50
    Registered Users Posts: 9,605 ✭✭✭gctest50


    rcanpolat wrote: »
    .........
    would you know what kind of potentiometer i would need?

    A potentiometer is not the best way of going about it

    When the lights are at say half-brightness it will "dump the excess" as heat

    You could use PWM ( pulse-width-modulation )

    Basically it turns the lights on and off really quickly

    Obviously the more "on" time , the brighter the light

    The unit won't get so hot because it is just turning the lights on or off

    Jeep and a few more use it apparently


    https://www.youtube.com/watch?v=T5dh9iXOaRc


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  • Options
    #7
    visual
    Closed Accounts Posts: 3,268 ✭✭✭visual


    gctest50 wrote: »
    A potentiometer is not the best way of going about it

    When the lights are at say half-brightness it will "dump the excess" as heat

    You could use PWM ( pulse-width-modulation )

    Basically it turns the lights on and off really quickly

    Obviously the more "on" time , the brighter the light

    The unit won't get so hot because it is just turning the lights on or off

    Jeep and a few more use it apparently


    https://www.youtube.com/watch?v=T5dh9iXOaRc

    Jeep use it to control the electric fan but I wouldn't recommend it for fog lights


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    #8
    gctest50
    Registered Users Posts: 9,605 ✭✭✭gctest50


    Wouldn't want to use it unless you know what yer at - easy for it to annoy the ABS / fuel injection and kill you


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    #9
    gctest50
    Registered Users Posts: 9,605 ✭✭✭gctest50


    visual wrote: »
    Jeep use it to control the electric fan but I wouldn't recommend it for fog lights

    Volvo used it for lighting stuff, keeps the bulbs at a happy 13v


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    #10
    visual
    Closed Accounts Posts: 3,268 ✭✭✭visual


    rcanpolat wrote: »
    my fogs are metal so they are grounded. would you know what kind of potentiometer i would need?

    i would change the bulb to a lower wattage but the day i run into thick fog i would like to be able to boost the light for better cut through

    if your using standard bulbs that is 110W
    your potentiometer would be the size of a large transformer and would get very warm.

    you really need to read up about fog lights its not about high power to cut through the fog.

    Fog lights in some cars are rated as low as 35w while in others its 55w and there is some in-between at 45w

    the fog light is angled down and doesn't extend as far in front as your dip head lights but has a wider beam side to side than dip beam lights.
    This is to stop light being reflected back of fog and into your eyes reducing visibility. Its also the reason you don't use high beam in fog.

    I have seen spot lights that have a small 5w bulb that lights up as a marker light when cars side lights are on and a second 55W bulb for when the spot light is on. maybe you could do that
    or as gctest50 suggested build a PWM circuit

    http://www.jaycar.com.au/productView.asp?ID=KC5225

    but I wouldn't recommend going to all that trouble unless your big into electronics


  • Options
    #11
    visual
    Closed Accounts Posts: 3,268 ✭✭✭visual


    gctest50 wrote: »
    Volvo used it for lighting stuff, keeps the bulbs at a happy 13v

    forgot about the internal dome lights in Jeep they also have auto dimmer and timer


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  • Options
    #12
    rcanpolat
    Registered Users Posts: 146 ✭✭rcanpolat


    visual wrote: »
    if your using standard bulbs that is 110W
    your potentiometer would be the size of a large transformer and would get very warm.

    you really need to read up about fog lights its not about high power to cut through the fog.

    Fog lights in some cars are rated as low as 35w while in others its 55w and there is some in-between at 45w

    the fog light is angled down and doesn't extend as far in front as your dip head lights but has a wider beam side to side than dip beam lights.
    This is to stop light being reflected back of fog and into your eyes reducing visibility. Its also the reason you don't use high beam in fog.

    I have seen spot lights that have a small 5w bulb that lights up as a marker light when cars side lights are on and a second 55W bulb for when the spot light is on. maybe you could do that
    or as gctest50 suggested build a PWM circuit

    http://www.jaycar.com.au/productView.asp?ID=KC5225

    but I wouldn't recommend going to all that trouble unless your big into electronics

    I checked yesterday, bulbs are 12v 55 watt halogen. What about moving to led and then using a potentiometer. No difference?


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