henk Posted March 31, 2022 Share Posted March 31, 2022 I got 50+ carling rocker switches but all 24v. Can I just replace the led by a 12v version or is there more involved? Quote Link to comment Share on other sites More sharing options...
Snagger Posted March 31, 2022 Share Posted March 31, 2022 That would be the only difference. The contacts will be the same inside as two lines for production would greatly increase production and logistics costs. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 31, 2022 Share Posted March 31, 2022 Just try connecting them up, they may work without modifications . Quote Link to comment Share on other sites More sharing options...
L19MUD Posted March 31, 2022 Share Posted March 31, 2022 53 minutes ago, Bowie69 said: Just try connecting them up, they may work without modifications . I would second this. You are going to be putting half the expected voltage across the LED so worst case is it won't work, best case you are good to go LED's often have quite a broad working range. Lots of marker lights work on 12v and 24v 2 Quote Link to comment Share on other sites More sharing options...
Escape Posted March 31, 2022 Share Posted March 31, 2022 I've recently taken apart a few Carling switches to see what options I had for rewiring them for specific purposes (me keeping busy with unimportant gadgets instead of cracking on with my Range Rover build...). This included a fair bit of research in the Carling technical files. I can confirm the switch part is identical, I don't even think there is a difference in materials used, only a different rating for higher voltages. The LEDs are not powered directly, but have small resistors between the springs and contacts. Those are quite important, I blew 2 LEDs while testing because I forgot to install the resistors... In your case, I fear the LEDs will not light up because there's not enough voltage left. But that's the worst that can happen (as above), so no harm in trying. The cure would be to source suitable resistors of half the value. Those might be hard to find, so maybe easier/cheaper to replace the LEDs with either 12V LEDs or simple bulbs. Filip Quote Link to comment Share on other sites More sharing options...
Ed Poore Posted April 6, 2022 Share Posted April 6, 2022 LEDs are current mode devices - i.e. the current flowing through them dictates the brightness. Too much current and they go pop as @Escape discovered. The cheap and dirty method of limiting the current is to use a series resistor. LEDs do require a minimum voltage to operate (anything up to ~2.6V typically), any less and they just don't function. Above that "forward voltage drop" then the current flowing through it dictates the brightness. So voltage will not kill an LED but slightly more current than intended and pop goes the weasel. Running a "24V" LED (or one designed for a 24V) system on a 12V system which has a current limiting resistor will just dim the LED. (There can be quite a lot more complications but for the purposes of a carling switch this will suffice). Quote Link to comment Share on other sites More sharing options...
Snagger Posted April 7, 2022 Share Posted April 7, 2022 1.5v for red and amber, 2v for green, close to 3v for blue, purple or white. Quote Link to comment Share on other sites More sharing options...
Ed Poore Posted April 7, 2022 Share Posted April 7, 2022 For "standard" LEDs yes. We've got some LEDs made for us that have much higher forward voltage drops because of their internal construction. Internally yes they see those diode drops but externally they need to be driven harder. Quote Link to comment Share on other sites More sharing options...
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