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Fade in & out of interior lighting / dome lighting?

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  • Fade in & out of interior lighting / dome lighting?

    I need 4 simple boxes of magic that'll softly dim in and out LEDs in my doors (puddle lights and warning lights).

    Anyone able to make something, link somewhere or draw something?

    Thanks!

  • #2
    Do you want them to flash constantly or do you want them to fade on then stay on until you open the circuit again to have them fade off?

    If that's the case, you would have your 12v power source go into a resistor then a capacitor, your LED and resistor will be ran in an adjacent circuit with the capacitor.

    The first resistor will slow the power going to the led and being that the capacitor is parallel to led/other resistor, it will charge. When the circuit is turned off, the cap will continue to supply 12 volts to the 3v led... the 3volt led will continue to consume energy till all 12volts are gone... fade off.

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    • #3
      Yep I want them to just fade on over about 2-3 secs, stay solid, then fade off over about 2-3 secs again... If I could make it adjustable that'd be even better!

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      • #4
        Originally posted by TheGuv View Post
        Yep I want them to just fade on over about 2-3 secs, stay solid, then fade off over about 2-3 secs again... If I could make it adjustable that'd be even better!
        The resistor inline with the LED would be used to bring down the 12v to 3v so as not to burn out the LED, but if you put an adjustable resistor before the cap... there you go. Also, putting one after the cap. you should be be to slow down the fade off more too.

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        • #5
          Is it incandescents, or a other or a mixture like LEDs, CFLs, halogen etc?

          If NOT incandescents, the PWM is the only realistic "proportional" method.

          If incas (else halogen), there are various "analog" circuits....

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          • #6
            It's puddle lights in the door cards which use 501 wedge LED or SMD bulbs.

            So if I do:

            [adjustable resistor] -- [cap] -- [fixed resistor] -- [501 LED Bulb] -- [adjustable resistor]

            I should be in business?

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            • #7
              Wait- just realised! The entire reason I wanted to use Audi OEM door markers and puddle lights was so that a bulb could easily be replaced or the colour changed etc... It'll always be LED/SMD bulbs, but they come with the resistors to work off of a 12v feed in to the bulb holders... So I assume that means I just eliminate the fixed resistor from my dodgy diagram above?

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              • #8
                Originally posted by TheGuv View Post
                Wait- just realised! The entire reason I wanted to use Audi OEM door markers and puddle lights was so that a bulb could easily be replaced or the colour changed etc... It'll always be LED/SMD bulbs, but they come with the resistors to work off of a 12v feed in to the bulb holders... So I assume that means I just eliminate the fixed resistor from my dodgy diagram above?
                If the LED you buy is made for 12v feed then yes it has a resistor already and you don't need the "fixed resistor". But remember the led is in parallel or adjacent to the cap. So its: power source -- resistor -- (cap and led circuit) positives -- (cap and led circuit) negatives -- resistor.

                Bench test this. But I think this should work (at least on paper).

                Hope this helps

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                • #9
                  I just bench tested this... Works great. I kind of like it. Fades in quick so you can see what you need to see but dims off slowly. Nice ambiance.



                  Damn you!!! Now I'm going to have to rip my car apart and put these all over the place.

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                  • #10
                    Okay I need help in this now. Is there an electronic component that will gradually allow energy to flow from 0 to full potential?

                    I ask because I notice that circuit I made works perfectly (fade on - fade off) but with the two resistors the LED out put is reduced. The initial resistors slows the on process but caps the potential under that of voltage for optimal brightness on the LED.

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                    • #11
                      Awesome! It's a good mod

                      Is it not just the rating of the cap that's limiting the led?

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                      • #12
                        Also, car door switches are negatively switched, how would I overcome this? I would like to avoid the use of clicking relays!

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                        • #13
                          http://sound.westhost.com/appnotes/an004.htm

                          Interesting!

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                          • #14
                            Originally posted by TheGuv View Post
                            Is it not just the rating of the cap that's limiting the led?
                            No, the cap is there just to power the LED after the switch is turn off, so it effects the fade out time but nothing to do with the fade on.

                            Hmmm... I'm going to try res -- cap -- led in series.

                            What it might come down to is using a 555 micro-controller. Now I just have to learn how to use one.

                            UPDATE: res -- cap -- led in series... didn't work

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                            • #15
                              Is the res the correct value for the LED?

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