L.E.D's, and the voltage and current going to the MFD lights?

[Gazza_DJ]

i want to change the MFD lights to blue LED's. someone on here used to sell them, but as i understand it doesnt do them anymore?
anyway, seeing as i have a bit of experience with electronics, i want to make an multi-LED backlight myself. so i know what resistor(s) and LEDs to use, i need to know the maximum voltage and current that passes through the PFD backlight circuit. short of getting a multimeter and measuring it, does anybody know these figures?
IIRC, normal LED's do not give off a variable intensity of light - they are either on or off. what is the name of the LED's that are variable?

thanks :dance:

[Hoops]

Oddjob (http://www.corsa-c.co.uk/forum/member.php?u=2584) is your best bet as he does LED lighting for the B.

[Oddjob]

I'd use 510ohm for 3.2v LEDs and 560ohm for 1.6v LEDs, most compaines seem to supply 470ohm tubular resistors with their LEDs which is ok for 12v but as you know the voltage sits around 13.6v on a car when the engines going and can go as high as 14.4v on occasions, I've found that this causes failure in the LEDs with 470ohm resistors.

Forget the volts in the MFD, all the units seem to get around 13.4v when the cars running, cater for that voltage and you'll be fine.

You can use normal LEDs or surface mounted diodes (SMDs). SMDs are more fiddly but much more robust IMO but aren't suited for all applications.

[Gazza_DJ]

yes, but i need to know the current that flows through it, so i can work out the maximum current that will flow through the circuit, so then i can work out the correct value for the current limiting resistor :thumbs:

[Oddjob]

Not being funny here Gazza but your going overboard with this. Assume the max voltage will be 14.4v, allow for that in your calculations and you should be more than safe. If the voltage ever goes above 14.4v the state of your LEDs will be the least of your worries.

LEDs are fine with over resisting, it's under resisting that's the problem, over resisting them will just make them slightly dimmer and most are too bright anyway. I have to mod my LEDs to make them appear less bright than they actually are, seems odd but it's true. A lower MCD would be ok but then the light I want, which is sideways, wouldn't be as bright then.