Just sharing: My Dash Lighting Project
 

I finally finished it.. after procrastinating for 2 weeks... hehehe..

after countless times looking for the right materials..
after 6 hyper white LEDS
after 2 50 OHM resistors which was later scrapped and replaced with 2 150OHM resistors
after 8 pcs of pin connectors
after soldering the pieces together...
finally did it.

i'm quite happy with the results... though i think i still have to re-adjust the focus of the LEDS to fully light up the dash...

the only problem is.. now it doesnt match my lights up front.. eheh. dunno maybe its just me being OC...i think i need to buy me some hyper white H4 bulbs...

and the final result is...

Nice LED project. I'm thinking of doing the same to my SDL since some of the window switches and dash lights are burned out. I'm really not looking forward to ripping everything apart though.

Wow shes bright. You can even read the odometer without turning on the cabin lights. :eek: :D :cool:

That is great. Mine are really not very good.

Is there any chance of a wiring diagram as to how you put it all together? Wiring is not my strong point. But I can read and follow directions!!!!

Thanks,

Stephen

I agree with Stephen. Directions for the electrically challenged. Looks excellent, by the way. I see somebody else out there doesn't have a tach.

That is so pretty!
My lights are competely dead, tell more!
How much is that stuff?

If I am not mistake in my view of the picture, you are using two 150 Ohm Resistors (in series?)?

If so...here is a schematic (MS-PAINT!) for you non-electronic types (attached)

The parts would be probably around 5 bucks...perhaps even less.
Radio Shilack would have all these parts....but remember...they aren't very bright down there ;)
If you are going to use 2 150 Ohm resistors (?) then you should make sure to get the same type LED's (Ultra Bright or whatever it is)
These use more current and thus the lesser value of the resistor

Smaller Value Resistors = More current

Too much current and you fry your little silicon based friends :)

Enjoy

the diagram brandon showed is ALMOST right...

i only used the two 150 OHM resistor.. (didnt use the 2 50ohms).. from the diagram.. just use one resistor for the set.. and the other one goes to the other set.
-------------------

3 LEDs on each side of the dash light panel.. with 1 resistor in series with teh 3 LEDs. ..

so you will have two (2) sets of 3 LEDs in series with a resistor on each set.(a set would look like the 3rd picture from the first post.)

i didnt have any problem setting up my dash since the PO already broke the prisms on my dash.. hence i just took them off.. (you may have to find another way to route the wires and the LEDs if yours is still intact and you dont want to ruin the dash) ...from the back...wire these sets to the connector. you'll have to find which of the sides of the connector goes to teh positive.. and which side goes to the negative. LEDs dont light up with the wrong polarity.

i'll try to draw a diagram... though drawing is not one of my forte... ehhehe

At teh very least, the diagram will tell you how to hook the diodes together and what side goes to positive. Just have to play with the resistors. Hope it helped

brandon :)

I found this to be very helpfull for this project:

http://maxmouse007.tripod.com/w126_LEDS.htm

sam

watch out - error in resistor values on that link
 

I don’t know if anyone has pointed this out before but the value of the resistors as indicated 390K Ohms is wrong. I believe 390 Ohms is the correct value.
“K” indicates thousands, so 390,000 Ohms will only allow .000033 amperes to flow. That will not light the diodes at all.
You need approx. .03 amperes (30 milliamperes) for reasonable brightness.
390 Ohms would provide approx. .032 Amperes considering the voltage drop of the LED. The previous post recommended two 150 Ohm resistors in series - that is better, and shows that the ballpark value of the resistance is in the proper range, ie. NOT K Ohms!!!!
The email on twitty's web page has a wrong Email address, I sent a comment direct but it bounced.

Can they be dimmed?

LEDs are not easy to dim.. If you connect a potentiometer to them you can sort-of dim them, but what happens is as the current to the LEDs drops, they do not dim smoothly, they'll 'drop out' one by one, and the color will change as they dim. Its not ideal.

The best way to dim them is to connect them behind some PWM (pulse width modulation) circuitry that turns them on and off 1000 times a second or so. Then the dimmer would control how long it stays on in proportion to how long it stays off.

Like this:

The circuitry is not complex, in the form of a microcontroller (there are some purpose built microcontrollers just for dimming LEDs), but its more complex than just 'wire it up'.

Here is an example of a simple LED dimming circuit: http://www.web-ee.com/Schematics/LED%20Dimmer/LED_Dimmer.htm

peace,
sam

stupid question?
 

Why is it necessary to use a resistor? are the leds that delicate?

I put a red multi LED light in my boat last year I just wired it normally into the 12v system, (maybe it had a resistor built into the plastic case?)

thanks,
Robert


Ps. Looks great BTW! In my jeep I use a flashlight to peer at the last 2 working gauges.

See Brandon314159's post earlier. One selects an appropriate resistance to get the desired current flow for the LED. As he points out, too much current will damage them.

I did read it, but given my rudimentary knowledge of DC, Shouldn't the LED draw whatever amount intended by the person who designed it. Is the automotive DC environment a particularly harsh one? or is this SOP for all LEDs?

thanks,
RObert

A great solution
 

As I understand it, an LED is designed for a specific range of volts. If it gets too few, it won't emit light. If too many, it will burn out. Most are below 12v, so if you put 4 3v lights in tandem, this will amount to the needed 12v and they will both shine and last,

Is there some sort of flap or thingie hanging down in front of the LEDs to diffuse the light?

What are the specs on the lights, with regard to voltage and amperage, if you don't mind me asking.

LED's are current sensitive devices. They drop around 1.5-2volts per unit UNLESS you have one specifically designed with a resistor built in for use with 12-13volts.
These are not uncommon as they save a bit on support components.
The current that a single LED uses varies with its type, the high intensity ones using much more and the regular using much less.
If you give them too much V or too much I (current), you will burn them out (semiconductor material burns up) or the top half of the LED will blow off. Had it happen a few times when playing around ;)

LEDs, unlike regular light bulbs, are current devices, not voltage devices.

Since we are accustomed to working with voltage devices like light bulbs, and variable voltage supplies, like potentiometers, then we need to think differently when working with an LED.

As you give voltage to an LED, it won't pass any current until you reach its breakdown voltage, usually somewhere around 1.5 volts, at which point the current flowing through it will jump from 0 up to a few milliamps, and it will glow dimmly. As you increase the voltage, the current does not respond linearly, it is a very steep uphill slope from here, and once you hit 2, then 3 volts the current starts to skyrocket. When you hit around 2ish volts you are passing maybe 30ma, and getting good brightness, but above that current goes up so fast that you rapidly destroy the LED.

You either need a constant voltage/variable current power supply (which do exist, but you probably don't have one unless you already know what it is), or you need to limit the current going to the LED with a resistor. However, you can't just plop in a variable resistor and expect to get dimming, because turn it up too high and you pop the LED, and too low and you get nothing. You can change the current, but not the voltage.

Here is another diagram, with another way of thinking about LEDs, that offers a simple constant current type supply by using a common v regulator:

http://www.mikesflightdeck.com/led_dimmer.htm

If you don't understand any of this, just follow the schematics, and trust us. ;)

peace,
sam

wow!.. nice discussion going.. one thing that i didnt know is about the dimming of LEDs.. well i guess i just learned something new... and to think i was entertaining the idea of putting a potentiometer... guess it is not a straightforward thing.. (especially for someone like me still learning about electricals.. eheheh)

thanks for the inputs.. this would greatly help me improve on my project..

as for the shroud.. yes there is a shroud that covers the LEDs....

I took the easy way and accomplished almost the exact same thing. Cost $10 and about 15 minutes start to finish. I bought a pair of LED reading/maplights sold in pep boys, Discount auto(now advance auto) also think JC Whitneys carries 'em. The 2 small lights in a black swivel bases area bout 1" long and the have wire leads about 2' long that are energized by one wire for your cigertte lighter. I attached each light(outside of the dashboard) on the side housing of the speedometer housing. The bases have that 3M adhesive on them and once attached, all you have to do then is swivel and focus the lights on the gauges and adjust them for glare. Mine easily illuminated the speedo and the temp gauge(main concern). the excess wire was routed along the top of the speedo case and down under the dash ending in the cigerette lighter. Looks just like the thumbnail in the opening post.

When the weather gets nicer I'm going to be doing this same project, but instead of using three white LEDs per side, I'm going to use two white LEDs and one UV LED, and then use amber glow in the dark paint on the needles so they luminese on their own. :) Fun stuff.

-sam

Would a VU LED put out enough watts to do such a thing? If so, thats a good idea :)

I feel better now, it's clear as mud now! Thanks:eek::eek::eek:

Just bookmarking this thread here :D

Recycled
 

for new members.