led wiring
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=123834
Printed Date: July 12, 2025 at 5:59 PM
Topic: led wiring
Posted By: 24inchranger
Subject: led wiring
Date Posted: October 08, 2010 at 1:02 AM
hi all i have 1 LED that needs to be controlled by two different circuits but the problem is that one circuit is const +ve and switched -ve and the other is opposite const -ve switched +ve im having a mental blank and can figure it out..
Thanks
Andrew
Replies:
Posted By: i am an idiot
Date Posted: October 08, 2010 at 5:57 AM
Use a relay to convert the polarity of one of your sources. Use the relay on whichever circuit will only be on when the vehicle is running.
https://www.the12volt.com/relays/page1.asp
Posted By: KPierson
Date Posted: October 08, 2010 at 1:47 PM
Use a 2n3904 NPN transistor on the (+) switched output and convert the (+) to a (-). (any general purpose NPN transistor should work).
Connect the base to the (+) output through a 470 ohm resistor. Connect the emitter to ground and the collector is your new (-) output. These parts can be picked up at a local electronics retailed (like Radioshack) for under $2.
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Kevin Pierson
Posted By: oldspark
Date Posted: October 09, 2010 at 1:55 AM
Or 2 else 4 diodes if my intuition is right (ie, a bridge rectifier).
Posted By: 24inchranger
Date Posted: October 09, 2010 at 5:25 PM
will try the transistor method as i happen to have one here.
Thanks
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