I purchased 50 bright blue led's 2 month ago, and finally today got around to test them. I want to light up my footwells but don't yet know the best way to wire them up or fix them in place.
Also i need to purchase some resistors to drop the voltage from 12V to 3.4V so the led's don't burn out.
Oh, and before anyone mentions it, i've read the posts already in the DIY guide sections.
Any tips or advice on putting in switches etc would be appreciated.
LED's finally tested
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Josh_PoloGTi
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well, if you wire 4 up in series, then each one will get about 3v....
working out the right resistance involves some kind of kooky physics maths that i can no longer remember... may well require you using an ammeter and/or measuring the resistance of the LEDs with a multimeter. V over A equals I or something.
wiring it in just requires you finding a spare positive lead (or even a used one with enough space for you to clip a take-off onto), putting a switch somewhere, finding a good spot to earth it, then just putting bits of extruded insulated metal between them. So long as it's all hidden behind the dash plastic it doesn't matter if it's messy.
(do NOT insert pics of my rear speaker or foglight wiring here
)
working out the right resistance involves some kind of kooky physics maths that i can no longer remember... may well require you using an ammeter and/or measuring the resistance of the LEDs with a multimeter. V over A equals I or something.
wiring it in just requires you finding a spare positive lead (or even a used one with enough space for you to clip a take-off onto), putting a switch somewhere, finding a good spot to earth it, then just putting bits of extruded insulated metal between them. So long as it's all hidden behind the dash plastic it doesn't matter if it's messy.
(do NOT insert pics of my rear speaker or foglight wiring here
)-
GroovyCarrot
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I think the equation you're after is V=IR (voltage = current x resistance), although I guess a more useful form for this is R=V/I.
However, a far better way of doing it would be to wire the LEDs up in parrallel, each with their own 240-330 ohm resistor, and wire them into the 12v dash dimmer wire so they light up when you turn your side/headlights on (ie when it's actually dark enough to see them
).
That's a rough idea of how it should be wired. You can then chain as many more resistors / LEDs onto that in the same manner as the first one, and it won't affect the brightness of the LEDs.
[EDIT]: The easiest place to find a dash dimmer wire and an earth lead is either the back of your radio (wiring layout here) or the back of a backlit cigarrette lighter (the kind with a ring around it which lights up when you switch your lights on).
However, a far better way of doing it would be to wire the LEDs up in parrallel, each with their own 240-330 ohm resistor, and wire them into the 12v dash dimmer wire so they light up when you turn your side/headlights on (ie when it's actually dark enough to see them
).That's a rough idea of how it should be wired. You can then chain as many more resistors / LEDs onto that in the same manner as the first one, and it won't affect the brightness of the LEDs.
[EDIT]: The easiest place to find a dash dimmer wire and an earth lead is either the back of your radio (wiring layout here) or the back of a backlit cigarrette lighter (the kind with a ring around it which lights up when you switch your lights on).