Type_LT

I noticed last night that the gauges on the 86t I'm buying were poorly backlit. I read somewhere that this is due to lack of reflective coating that spreads the light from the dash bulb(s). I was thinking it would be nice to use white "LED's" to light my dash, it would really be nice to have a sharp pure white light, rather than the dull yellow glow. Are there better lighting solutions? I'll be sure to post my work if I do find a proper way of using white led's to light the dash.

(Almost) My 86T

keith

umm, someone here was doing this... I don't recall who at this moment (or is it whom?).

The individual(s) involved was/were going to post the procedure...

I, too, am very interested in this...

Perry 951

Olli has it set up in his 951, but never posted pics or a way to do it. I bought a mess of white LED's, and began the process. It looks like they will work in most of the lighted switches (just have to be careful).

Problem is that the LED's are 3 volt, and stock is 12. Some sort if resistor will be needed to drop the voltage on them. I am not an eletrical guy, so some help is appreciated.

Since mine is all apart, I had planned on installing all the LED's as well.

Other thing that would help is a smaller LED than standard. Many of the lights in the switches are very small, and an LED would take some work to get in there.

Olli Snellman

I have done it with bright blue leds.Unfortunately the procedure has not yet documented.We have plan to do similar conversion for some other cars and there's a plan to photo the whole procedure.
In my version the original lights were replaced with 3 watt leds with resistors.Leds & resistors were soldered to the original light "sockets".The light is very blu and very bright, like VW's have.
A friend of mine made a conversion with red leds.He installed leds in the place where light tunnels were.In this mod the difficulty is to get the leds to the right position; there's the possibility to get shadows and recelctions.The procedure i used is better, but it will demand more work.

Olli
'88 951

sm

Olli:

Did you replace the bulbs that are in the Climate Control unit? The ones in mine are getting pretty dim.

sm

Type_LT

Good so someone is going it.

perry951: You can purchase led's that operate at 12v from the start, small ones and large ones.

I'll probably do this mod over christmas it should be hard at all as long as you know how to get the dash off (which I don't yet)

keith

using a smaller LED and resistor - will that ensure more longevity than using a 12v LED?

In addition, how would one deal with the clock to change its color to match the rest of the lights (like if you were going VW blue, for instance...)

Type_LT

Keith: A 12v led will last as long as a 3v led as long as they are not overdriven too much. They will certainly last longer than the car, probably 100 years into the future

I'm not sure how you'd get the color just right, that would be something I would worry about too, i'm picky.

marksportcts

As long as they haven't been touched by GM.
How many Caddies have you seen with the long LED brake light with a bunch of them burned out? I've seen a good dozen.

Olli Snellman

What comes to the other lights of the dashboard; i have located small enough leds which could be installed into the switches and heater control & clock.I follow the VW theme; blue on meters and red on switches.I will start this project within a week.

Olli,
'88 951

bs

LED stands for "light emitting diode", hence these devices are formed from a diode, or a single junction between P-doped silicon and N-doped silicon. Without getting into a lot of device physics which i don't even remember, the voltage drop across a PN junction is about .7 Volts. Perhaps there are people out there selling LED's as "3V" or "12V" but in actuality there is no such thing. What is important as far as brightness and longevity is the CURRENT going through the LED. If you buy from any good source, the package (or the catalog you ordered from) should spec the max operating current and a light output and some nominal current. For "bright" LED's i'd say a ballpark figure is maybe 20 or 30 mA. So, how does this pertain to voltage? Well, if you try to drop more that .7V across a diode, it'll burn out fast, hence the series resistor that you all mentioned.

The current through your LED is controlled by the value of this resistor. To compute it's value, use ohm's law, R=V/I. you know the voltage drop across your resistor (supply voltage minus diode drop), and you get to pick the current, and these two give you the resistance. for example, if you think your system runs at 13.5 Volts and you want 30 mA (Amps * .001) of current through your LED, then:
R=(13.5 - 0.7)/(.030)= 427 ohms.

that's actually a pretty decent amount of current... if you are using a small LED you might want to go with around half of that, or a roughly 1k resistor. Your best bet is to buy LED's that spec an operating current.

Ben.

Type_LT

bs: I'm not saying your wrong because your not, it is best to limit the current going into the bulb. However, don't most led's have built in resistance?

P.S. I'm an electrical engineer in progress, 1 year left for my b.s! Wee

bs

LT:

i know there are some that do, maybe these are the ones that people were saying they saw specified by voltage. Personally i have done most of my ordering of such things from electronics supply houses such as digi-key and they have very few with built in resistors. perhaps if i were looking at auto-parts or hardware stores i would have seen a "12 volt LED" with some internal resistor already selected for that voltage.

be glad you have a year left. now is a damn bad time to be looking for a job as an EE... in fact, it's a damn bad time to *have* a job as an EE--layoffs all around here in north cali.

daly944

how easy is it to get to all the bulbs that need to be replaced? How many are there? thanks

Type_LT

bs: Hope you keep your job.