# Any 12vDC electronic gurus here? **URL:** \ **Category:** PittSpeed Off Topic\ **Created:** [December 11, 2008, 2:56pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046 "2008-12-11T14:56:00Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![fah\_quad](https://avatars.discourse-cdn.com/v4/letter/f/ac91a4/32.png) [@fah\_quad](https://forums.speedlife.net/u/fah_quad)\ **Post date:** [December 11, 2008, 2:56pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046/1 "2008-12-11T14:56:00Z")
I need to figure a way (with a relay or whatever) to dim one set of lights when another gets turned on. I’m figuring a relay of some sort gets tripped when 12v hits it, and that in turn runs lower voltage via a resistor or something to the second set of lights, thereby dimming them. When the first set turns off, the relay trips back and the second set goes full bright again. Ideas? ---
**Author:** ![PoisonousBeef](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/poisonousbeef/32/6007_2.png) [@PoisonousBeef](https://forums.speedlife.net/u/PoisonousBeef)\ **Post date:** [December 11, 2008, 3:02pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046/2 "2008-12-11T15:02:48Z")
Could you just use a 3-position switch? ---
**Author:** ![fah\_quad](https://avatars.discourse-cdn.com/v4/letter/f/ac91a4/32.png) [@fah\_quad](https://forums.speedlife.net/u/fah_quad)\ **Post date:** [December 11, 2008, 3:21pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046/3 "2008-12-11T15:21:07Z")
Yeah but I just don’t want any ghetto rocker switches or anything. I was hoping to make it occur on its own. I forgot to mention, the set I’m dimming is LED, which makes it somewhat tougher. ---
**Author:** ![PoisonousBeef](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/poisonousbeef/32/6007_2.png) [@PoisonousBeef](https://forums.speedlife.net/u/PoisonousBeef)\ **Post date:** [December 11, 2008, 3:35pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046/4 "2008-12-11T15:35:22Z")
So you’ve got 2 sets of lights and you need the 3 following options? Both sets on full Set A on, Set B dimmed Both sets off Do you want it so that Set B is dimmed as the “base” state on your light switch but it was wired into your car’s “accessory” switch? This would keep Set B on any time the car was on, but it would be dimmed unless you activated the other light switch. I’ve seen multi-element switches that might handle this type of setup, let me see if I can find anything for you. Edit: Sorry I misread the original post. Sounds like Joe can help you. ---
**Author:** ![fah\_quad](https://avatars.discourse-cdn.com/v4/letter/f/ac91a4/32.png) [@fah\_quad](https://forums.speedlife.net/u/fah_quad)\ **Post date:** [December 11, 2008, 3:37pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046/5 "2008-12-11T15:37:07Z")
A. Low beams off- LED’s on full bright B. Low beams on- LED’s dimmed by half or so That’s all. ---
**Author:** ![Darkstar](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@Darkstar](https://forums.speedlife.net/u/Darkstar)\ **Post date:** [December 11, 2008, 3:41pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046/6 "2008-12-11T15:41:21Z")
I’d contribute to this, but I feel as though this is for some sort of ricey endeavor therefore I shall not. ---
**Author:** ![fmfkid250](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/fmfkid250/32/5973_2.png) [@fmfkid250](https://forums.speedlife.net/u/fmfkid250)\ **Post date:** [December 11, 2008, 3:41pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046/7 "2008-12-11T15:41:38Z")
> [@Is this ethical/legal?](https://forums.speedlife.net/t/is-this-ethical-legal/38965/15): > > A. Low beams off- LED’s on full bright > B. Low beams on- LED’s dimmed by half or so > > That’s all. I can do it. You have to Isolate the 2 with exactly that A Relay. When you say LED’s where are these? are they high power? Are they just a Raw LED? I belive leds like 2.1 Volts to begin with or something like that. ---
**Author:** ![fah\_quad](https://avatars.discourse-cdn.com/v4/letter/f/ac91a4/32.png) [@fah\_quad](https://forums.speedlife.net/u/fah_quad)\ **Post date:** [December 11, 2008, 3:43pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046/8 "2008-12-11T15:43:56Z")
Newer Audi OEM equipment has LED’s dim when the headlights turn on. I would like mine to do that. Here is thread of how project is progressing. [Click](http://www.pittspeed.com/forums/showthread.php?t=47610) The final project does not have an LED “strip”. It will be single 10mm LED’s from an Audi S6 wired in series. Oh, yeah, each headlight will have 13 LED, and each 10mm 1w LED has it’s own resistor already. The problem is, LED’s don’t dim in the same manner as regular bulbs. Cutting voltage doesn’t have the same effect. ---
**Author:** ![fmfkid250](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/fmfkid250/32/5973_2.png) [@fmfkid250](https://forums.speedlife.net/u/fmfkid250)\ **Post date:** [December 11, 2008, 3:50pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046/9 "2008-12-11T15:50:06Z")
> [@Ferrets??](https://forums.speedlife.net/t/ferrets/38968/4): > > Newer Audi OEM equipment has LED’s dim when the headlights turn on. I would like mine to do that. > Here is thread of how project is progressing. [Click](http://www.pittspeed.com/forums/showthread.php?t=47610) With standard LEDS Its 2.2mA the OEM \*\*\*\* is prob like 5K. you would need like a 12K resistor and a Single Pole Double throw Relay. ---
**Author:** ![fah\_quad](https://avatars.discourse-cdn.com/v4/letter/f/ac91a4/32.png) [@fah\_quad](https://forums.speedlife.net/u/fah_quad)\ **Post date:** [December 11, 2008, 4:05pm UTC](https://forums.speedlife.net/t/any-12vdc-electronic-gurus-here/201046/10 "2008-12-11T16:05:53Z")
Thanks. Gotta try to find a schematic now so I wire it up right. Here are specs for LED: High Power 20-80mA 4 chips White 10mm LED Vf: Typ 3.3V Iv: 10000-18000mcd @ 80mA, Total power 825,000mcd\* Iv: 20lm @ 80mA Max, 1W power ~53lm\* Viewing Angle: 55 Degree Color : Pure White They will be wired in series of 13 inside each headlight.