headlight halo xor switch

Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=131947
Printed Date: May 08, 2024 at 3:35 AM

Topic: headlight halo xor switch

Posted By: njlawman
Subject: headlight halo xor switch
Date Posted: August 04, 2012 at 4:10 PM

I recently installed some smoked projector headlights which have LED accent lights and also the "Angel eye" halo on my 2012 Mustang. According to the instructions the Halo and LEDs should be powered by tapping the wire for the parking lamps. However, since I have the automatic headlights i didnt want the trouble of always having to turn my parking lights on, so i tapped power from the fuse for the rear window defroster since that is on whenever the car is on Acc or run and so far that works fine. But my issue is i also want to enjoy the look of my new halos and i think it would be nice if they would flash with the parking lights whenever i lock/unlock the car. So basically, i want the halos powered by the parking lights when the key is not in the ignition but powered by the fuse I tapped as soon as i turn the key, since i would assuming that if they were powered by both sources simultaneously that would damage the halos.

As best I can tell with my limited knowledge a SPDT relay would accomplish this basic function but i want to be sure I have everything thought out correctly.

I've included a quick sketch I did of what i think would work but I wasn't sure if connecting pin 30 to the halos would work since one site i checked let me to believe pin 30 on a 5 prong SPDT relay couldn't be hooked to something other than the 12v DC.

Please let me know if this seems like it would work or if not what is needed to basically create an XOR between the parking lamps, the ignition, and the halos.

In case it's not clear in the drawing I was going to wire the connections as follows:

Pin 86: Accessory switched source (rear window defroster)
Pin 85: Ground
Pin 87: Either the same accessory switched source (if that will work?) or directly from the battery if I cant do that.
Pin 87a: Positive lead of parking lights.
Pin 30: Positive lead of Halos.

Any links to the relay or whatever else is needed to create this would also be appreciated.

Replies:

Posted By: njlawman
Date Posted: August 04, 2012 at 4:22 PM

Just noticed that my photo didn't work so here's another try. Sorry it's a little crude...

posted_image

Posted By: oldspark
Date Posted: August 05, 2012 at 2:41 AM

I'd use a single SPST relay with a fused +12V from the battery +12V to #30 with #87 to the new lights.

With relay coil #85 to GND, all +12V "input triggers" can be combined via diodes to #86.
Typical diodes are 1N4004 but any 1N400x will do.
The relay (ad lights) will the come on when any of the inputs are +12V.

Posted By: njlawman
Date Posted: August 05, 2012 at 9:31 AM

Could you explain exactly how to combine all the input triggers (ignition and parking lights) using diodes? I'm not exactly skilled in this area so I'm just trying to find a solution that is somewhat simple and doesn't overload the LEDs/halos.

Posted By: oldspark
Date Posted: August 06, 2012 at 5:36 AM

You can't overload new lights. Voltage determines what they take, not the "total available current".
Besides, what you parallel to the relay's coil has no impact on the halo/LED circuit other than close the relay that powers them.

See Isolating Door Triggers - namely the following fig:
posted_image

The lower "triggers' are from whatever +12V trigger sources you want.
The upper "to positive alarm door trigger input becomes you relay's #86.
Add more diodes for more inputs.

PS - I am NOT associating this thread's title with "exclusive-or" switching. If you do mean exclusive-or (XOR), please let me know.