turning white lights to use amber or white

Thread Starter

JoeBloggsWA

Joined Oct 31, 2023
8
Hi brains trust,

Total Newbie, sorry moderator if posted to wrong forum.

Most RV's install White light and would love a take advantage of using amber lights as well. Amber helps with detracting bugs.

Attached is a schematic that shows how to convert a typical positive/negative 12v single color light into using dual colors if the light has both led's installed.

Question, I don't understand the schematic and would be grateful if someone could explain how to layout the diodes and solder the cables back, lastly, the cabling to the dpdt switch. If anyone is able to show on photos how this works, I'd appreciate the effort because this is over my head.

Products required
1 x DPDT switch
Diodes
and of course the Amber/White light
 

Attachments

k1ng 1337

Joined Sep 11, 2020
906
The dashed lines in your schematic represent a component which comes in a package like an IC. I redrew the schematic because you only need 2 diodes and a SPDT switch. Follow the current path from +VE to -VE to understand how it works. Only use OEM automotive parts as lights from China are often illegal and dangerous. The diodes aren't really needed because the switch allows one current path at a time but they do provide extra protection against reverse currents in a fault scenario.


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bassbindevil

Joined Jan 23, 2014
817
The advantage of using the diode bridge is that it only needs two wires, so you could control multiple light fixtures from one switch without having to pull an extra wire.
 

sghioto

Joined Dec 31, 2017
5,368
I don't see the need for a bridge or any diodes in this application. The DPDT switch in the original schematic reverses the polarity of the DC supply requiring the bridge but why?
 

Thread Starter

JoeBloggsWA

Joined Oct 31, 2023
8
I have an RV that has only two wires embedded into the wall and back to the standard switch, I can't pull another wire through for the amber.

I need a solution to switch from white to amber light without pulling a third wire. I've only got a small amount of room behind the light which would be perfect for diodes due to the size.
 

sghioto

Joined Dec 31, 2017
5,368
Does your light fixture have both LEDs installed with a common negative? If so it might be feasible to use the RV chassis as the ground connection eliminating a return wire.
1700100409089.png
If no chassis ground connection then using two fixtures in this arrangement only requires 2 wires. Which is the original circuit shown in post #1.
The switch reverses the polarity of the voltage applied to the fixture and the diodes steer the current to the appropriate LED. Only drawback is the voltage drop through the diodes which is appx 1.5 volts.
1700148100444.png
 
Last edited:

MisterBill2

Joined Jan 23, 2018
17,729
I don't see the need for a bridge or any diodes in this application. The DPDT switch in the original schematic reverses the polarity of the DC supply requiring the bridge but why?
Please understand that many LEDs have a very limited reverse voltage tolerance. Often that maximum reverse voltage is about five volts. So I suggest never reversing the polarity to select which color gets used.
 

sghioto

Joined Dec 31, 2017
5,368
Assuming there are 3 wires between the switch and the lights. The purpose of this circuit is to make it work with existing wiring, which has two wires.
He didn't mention that there were only two wires available until post #7 and I presented two possible solutions in post #8.
 

Thread Starter

JoeBloggsWA

Joined Oct 31, 2023
8
Does your light fixture have both LEDs installed with a common negative? If so it might be feasible to use the RV chassis as the ground connection eliminating a return wire.

If no chassis ground connection then using two fixtures in this arrangement only requires 2 wires. Which is the original circuit shown in post #1.
The switch reverses the polarity of the voltage applied to the fixture and the diodes steer the current to the appropriate LED. Only drawback is the voltage drop through the diodes which is appx 1.5 volts.
Didn't think of this, I'll take look.
 
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