Board logo

led trailer indicator load resistors
sdh2903 - 3/4/13 at 03:09 PM

Hi all

just finishing off my trailer build and I was hoping the tintop would cope with the led indicators, but it can't. I accept the fact an electronic relay is the best solution but If I want to use the trailer with a different car then it's going to be a hassle, can anyone suggest some load resistors that work? there are loads on eBay but with all different ratings

cheers
Steve

britishtrident - 3/4/13 at 03:23 PM

P=VI re-arranging I = P/V for a 21 watt 12v bulb actual current = 21/14 = 1.5 amps


V=IR re-arranging R =V/I in this case 14/1.5 which gives a resistance of approx 0 .9 ohms

As the LED wiill take some current a 1.0 ohm 25 watt resistor should do the job, but a 1.0 ohm 50 watt resistor would be better

The dummy load resistor goes in parallel with the LED

rx7locost - 3/4/13 at 03:43 PM

quote:

V=IR re-arranging R =V/I in this case 14/1.5 which gives a resistance of approx 0 .9 ohms


Ummmmm 14volts/1.5Amps = 9.33 ohms on my calculator.

gremlin1234 - 3/4/13 at 04:46 PM

the very simplest (cheep, easily available, ) resistors are: 21w12v bulbs themselves

britishtrident - 3/4/13 at 04:54 PM

quote:
Originally posted by rx7locost
quote:

V=IR re-arranging R =V/I in this case 14/1.5 which gives a resistance of approx 0 .9 ohms


Ummmmm 14volts/1.5Amps = 9.33 ohms on my calculator.



Thats what the "approx" was for.................................

gremlin1234 - 3/4/13 at 07:03 PM

quote:
Originally posted by britishtrident
quote:
Originally posted by rx7locost
quote:

V=IR re-arranging R =V/I in this case 14/1.5 which gives a resistance of approx 0 .9 ohms


Ummmmm 14volts/1.5Amps = 9.33 ohms on my calculator.



Thats what the "approx" was for.................................


approx, an order of magnitude...

sdh2903 - 3/4/13 at 09:20 PM

cheers guys got some sorted from a very helpful gentleman on eBay.