Nate

You already know I've wanted blue light in my dash instead of the crappy green stock ones forever. Even more so as soon as my indiglo gauges get here! Problem is, the bulbs aren't a standard type and would be very difficult to replace with blue ones. One alternative might be to use little blue condoms but this would most likely reduce the light output quite a bit. So... I've been stuck unable to do it for a long time.

But I was looking for accessories for the computer I'm building (I'll post on that little project when I'm done, lets just say its water cooled for now ) and ran across this: Light Tape. I'm thinking I could disable the bulbs in my dash and run this tape through there! That would rock! I don't want it too bright but I'm sure that won't be an issue - I'll just mount the tape further from the dash if needed.

This still will leave a few green lights... the clock and the stock radio. The clock is a possiblility but I doubt I'm going to take apart the damn radio... though it would be awesome to complete the effect!

As for footwell lighting, the light tape would make it really easy to route and hide.

Another alternative to neon lights would be a cold cathode light. These are tubes that are 12" long and smaller around than a neon tube (they are .25 inches in diameter, thats less than your pinky finger!) and put out brighter light. Its bright even in daylight and is easy to hide as its small and a clear color when not lit.




I ordered a blacklight cold cathode for my PC () and it should arrive tomorrow, then I'll really be able to tell you if it is of quality. I would've gotten the light tape for my PC but it doesn't come in UV.

VICNYC_TL

now nate i want to see pics of a final product, becuase i like that idea. after your done i want to try

songoku

Great Idea... It'll look great!!!

Petrie1997

Yeah, that's what everyone's waiting on! Nate, I thought you said that you already got yours. Any word?

Peter.

SimTypeS

Nate, where did you order the cold cathode from? Do you think it would be sturdy enough to put in our car? (under the front seats, or maybe the footwell) I guess it matters if it comes with a DC converter, or if it can run off one, too. I wuold probably want to hook it up so it turns on when I open the doors, but also have it so I can turn them on whenever I want to, by themselves, also.
Keep us posted... I don't want to steal your idea, but... I think it would look cool.

Nate

I bought mine here. Its powered by a 12V invertor -- you give the invertor 12V DC and it gives the light whatever it uses. The light tape is also 12V DC already. Can't say if its sturdy enough yet, I'll know when mine comes today! I like that idea -- on when doors open and also on by demand! I'll have to steal *your* idea and let you steal my cold cathode idea at the same time. I'll probably go with the light tape for the dash as well as for the footwell lighting, to keep the color consistant and the costs down. But if you want a blacklight go for the cold cathode for sure (I'm doing blue).

Petrie1997, nope, as soon as I get mine I will post a bunch of pics. I can't wait either!

I'll post pics asap of the UV cold cathode tube when I get it and I'll order some light tape today

Nate

TommyBoiSxty9

Some very cool sh it nate!!
PiMp it up and let us know ---
Red would be sweet too!!
do the window swtiches light up? change those to--- wonder how hard that would be -- the guys on Max.org did their maximas

Nate

I haven't been able to find any post from you guys about it... what did you guys have in mind? I won't buy the light tape until I hear back from ya!

TBS9, good idea! Not sure how hard it is to get to the lights in the window switches but I'll try for sure.

Nate

Oh ya, I got the UV cold cathode. It doesn't seem very bright but thats because it is UV. It really is bright and lights up my computer case very well. I'm sure the blue ones are crazy bright! Its 12.25" long and about half the diameter of a penny. Very thin! And it doesn't have a ballast light a neon tube, its just a tube with wires could out the end. The wires go into a small circut board that is about 2"x1"x0.75". The tube has small velcro squares on each end and the circut board is backed with velcro for easy mounting. They are kind of costly at about $40 per tube but they are better than neons.

EDIT: Forgot the pic!

Nate

Got my tape! It came out in the pics like it is light indiglo blue but its really a much nicer dark blue.





Its a little of 1/4" wide:


The invertor:


Its pretty bright and I think it will work great! It comes with 5 connectors so I can cut it for a total of 6 seperate pieces lighting up. The only real bad thing is the invertor makes a high pitched noise when its on. I plan on fixing this by mounting it far away... possibly on the other side of the firewall? We'll see.

Now that I got the tape I see its called Californeon. Looking that up on the web I see its made for all sorts of stuff... they even sell it in 16ft lengths for pinstriping your car! Crazy. I probably could've gotton it a little cheap than the $50 I paid, though it did arrive very fast. Also the other kits I've seen don't come in 5ft lengths (bike kit is 2 10" strips, car kit is 16ft).

There are actually a lot of manufacturers for this sort of thing. You might search around and see what you find.

I'll post results once I get it installed!

Nate

Actually, upon taking a closer look... it comes with 5 connectors but it takes 2 connectors each time you cut it, so really I can only have 3 seperate sections of tape, unless I make my own connectors... but I have 5ft of the stuff. I'm thinking... one section on the left of the steering wheel, one large section to the right of the steering wheel (behind the AC controls/clock/radio - I don't have navi), and the third section down below, around the shifter.

Nate

Turns out the light tape won't work very well... but now I know what I'm up against. The bulbs shine in all directions and are in little holes, which makes the tape hard to get in there. Plus the tape isn't bright enough to shine the 2" or so, through the bluish filter thats on the buttons, then out he button face and still be bright.

I've taken the whole damn car apart, radio out, etc. I ahve pics of everything to show you guys in case you want to try something similiar.

Going to try and use a blue marker on the bulbs, we'll see how that goes. LEDs are out of the question unless we can find some that shine in all directions like a light bulb. I tried a couple and they shine too much forward, causing bright spots. Not sure what else to go for... Austin mentioned fiber optics but thats probably going to have the same problem as the LEDS... any ideas?

Nate

What I mean by bright spots is the LEDs shoot a beam of light, just like the end of a fiber optic cable would (I believe). Unless you could put some sort of bulb to spread the light at the end fo the cable? The light has to go in all directions. In many cases you are given one hole for one light to shine through two buttons.

I don't think you know what you are talking about... the tape I got was fine and there is no gas in any tape. The problem is that you can't get the tape down right behind the buttons, it needs to be about 2" away. The tape doesn't shine in all directions because it has to shine through a hole. And finally, there is a blue filter behind the button the blocks most fo the light. The stock lights are a white-yellowish color and through the blue tint come out the light green color you see.

Tinting the bulb blue didn't work. The blue tint made the bulb shine a truer white and less of a yellow color. It did shine through the button a light blue but it dimmed it too much. The stock bulbs need to be brighter.

I'm looking into blue LEDs that shine in a wide angle. This may be the answer. Also looking forward to hearing more info on fiber optics, and if they can shine in all directions. I'd like to get a move on this **** - my car is all taken apart!

As it turns out, taking apart the stereo and the heated seat switches, they use the same lights as the dash. The difference is they have little rubber coverings over them. The heated seat switches have a small yellow cover and the radio has blue covers. I will post pics of everything soon. The radio lights are integrated into the PCB (printed circut board). Disabling them may prove interesting.

On a side note, after removing almost my whole dash, my blinkers don't work. Not sure what component they are tied to, but since I'm going to be driving with a dismantled car, I'd like to have blinkers.

Pics are coming.

Fiddler

damn .. took me a while to find this link, but here are some LED's that are either out now or are about to come out.. they are incredibly bright and might work for what u need it for.....
http://ledmuseum.home.att.net/agilent.htm
good luck

Nate

Austin, the tape I have is EL tape - its essetially indiglo tape. I think this is what you mean by neon tape, I really doubt they fill tape with gas. The tape I have is not LEDs, it is a thin tape that glows with power. I'll most likely use the tape for footwell lighting when the door is open. Its bright enough to illuminate down there while remaining unseen.

Fiber optics may work then... if at the end I can cut back whatever material covers the cable and make it so it shines out the sides, if it is bright enough. But where to get this cable?

Thanks Fiddler, I've been researching for the past few hours and have found some interesting things. I also found the LED Musuem and the guy that runs it lives in downtown Seattle, where I work. Called him but no answer, I sent him an email. He should know what LEDs might work and where to get the best prices on them.

In a sec I'll post my findings.

Nate

Here is pics and descriptions of what I've done. It should help give you guys a better idea of what we are up against in this little project.

http://natestl.com/images/dash/dash.html


Anyone have any idea why my blinkers don't work? I think they require the little green plug for the select/reset buttons. I'm driving around like that!

Nate

Heres the number of holes and their sizes for all the bulbs we need to replace.

AC panel:
6mm x 5
5mm x 4

Cruise control switch:
4.5mm x 3

Sunroof switch:
4.5mm x 2

Heated seat switch:
4.5mm x 6 (3 in each)

Hazard light switch:
4.5mm x 1

Radio:
9 bulbs integrated into the PCB

Shifter:
6mm x 1

This brings us to a total of 31 lights. I might leave 5 of those as they are (2 for each heated seat "is on" hi/low lights and 1 for the cruise control "is on" light). But I think blue "is on" heated seat lights would be cool, the green "is on" cruise control light is probably fine though. So thats 30 lights in 3 different types of holes.

Edit: Note that I haven't yet taken apart the door to get at the window button lights. I'm sure they are the same kind of bulbs. Seems they wanted to keep it the exact same color so they used the same bulbs throughout and the same blue filters. I'm guessing 7 bulbs for the windows (4 for the driver, 1 for the rest).

Going with the LED idea, we need 6 that fit in 6mm holes, 4 that fit in 5mm holes, and 12 that fit in 4.5mm holes. They must be very wide angle LEDs so they illuminate everything they should and they don't cause "hot spots".

I've found a few... I just bought one of each of these:

125 degree viewing angle ($1):


120 degree viewing angle ($6):


160 degree viewing angle ($8):


160 degree viewing angle ($10, puts out a little more light):


125 degree viewing angle ($1):


125 degree viewing angle ($1):


I'll let you guys know what I've found to work best, or work at all. Should be interesting! I'm hoping one of the $1 LEDs works great! I sure as hell won't be spending $300 on LEDs! But in some places, like the single shifter light, one LED is going to be illuminating a whole lot. So there I think one of the big bright LEDs will work better. I just hope those little guys put out enough light.

Nate

Just had a thought driving home... if I have my own lights behind the AC panel then they will always be on. If you notice, the AC panel LCD and knobs aren't illuminated unless the blower is on. I wish there was a way to get the LEDs running on the same power the stock bulbs are... I bet I could tap into the stock bulbs power and run it to a relay that turns on the AC panel LEDs when they are supposed to be on! ****ing ingenious or what?

bebber

Nate, I see you're quite determined to give your dashlights a distinctively blue hue. About fiber optics, the primary purpose of a optical fiber is to transmit light from one end to the other with as little loss as possible along the way. For all practical applications, the optical fiber is encased in a sheath and light only comes out of the ends. I suppose you might be able to get some raw fibers that are unsheathed and shine light through the entire length of the fiber, but that light will just be a small fraction of the total light and will not be bright. Installing fiber is a difficult task too. I don't recommend it.

You're probably on a better path pursuing LEDs or brighter bulbs. Remember that bright LEDs are still very expensive and you have the joy of soldering on resistors on every LED. If you want a wider dispersion pattern, you might be able to use a fresnel magnifying lens. Just buy a cheap bookmark-type flat plastic magnifier and cut out the size that you need. Incandescent bulbs are crude technology, but still are worth considering if you can get brighter bulbs that can be coated blue and made to fit into the sockets without much modification. Mini fluorescent tubes, like the kinds used for LCD screen backlights, would produce the best results in my opinion but might cost you more dough.

Hope this gives you some options.

Nate

Bebber, determined I am! I am pretty sure 160 degree viewing angle LEDs will be sufficient... though expensive. 120 degree LEDs are much cheaper ($1). I think the LEDs will work out great!

Austin, I believe you'd be hard pressed to find quality blue LEDs for $0.50. A 5mm LED from the site you linked is $3 and says nothing about viewing angle. Blue is the most expensive color. And yes, I have some extremely bright blue LEDs already (a Photon III). If I were to buy LEDs for fiber optics it would be from Varad and they are $5.

Your fiber optics link doesn't "wipe out" what bebber said. Side glow cables require enormous amounts of light. End glow cables are only going to glow out their ends, I believe even if you peel back the cable's covering. I see nothing about a mix of these types. The only application here that I can see with fiber optics is to use endglow and have some sort of a bulb to disperse the light at the end. I still haven't seen enough to think that fiber optics would be any easier or work any better than straight LEDs.

bigmonkey70

Nate ... don't forget to try some STM type led. Available in hyper blue and is 160 degree too. That's what im thinking of doing.

Nate

BigMonk, what exactly are SMTs? Surface mounted LEDs, but whats that mean? Are they the type that are soldered directly onto PCBs?

Ahhhrg... the tape was for the dash lighting but it wasn't bright enough. What did you think it was for? Furthermore:Are you reading the same thread I am? :p What would I use fiber optics for?

Shoofin

I wonder what ever happened to those lighted pin-stripes they used to sell...They look similar to the thin strip dash lights....they turn on with the headlights...those were cool..
Ed

kchen

i want GAUGE !!!!!
Nate, anyword on our gauges ??

Nate

Wrong thread kchen. I'm still waiting... should have some news very very soon! Maybe even by tomorrow (Tuesday) morning.

Shoofin, the Californeon light tape that I have is that same lighted pinstriping stuff you are talking about.

Nate

Did you see this link?
http://natestl.com/images/dash/dash.html

Yeah, its too bad the groupbuy didn't collect orders very fast and then its even worse that we haven't been able to have them made very quickly after we finally got all the orders. But it'll be worth it to get something custom made for our cars. Tim gets to do that all the time, now its our turn! I know its a long wait and it sucks, but its only $80. Trust me, I want the damned gauges more than any of you guys! I bought 3 of the bastards. We will get them and they will rock.

bebber

Austin. I appreciate your looking out for my interests, but I have had my share of experiences with various forms of lighting. Even with the benefit of your enlightening lighting comments, I don't believe fiber optics is a good choice for dash light illumination. That is what we are talking about after all.

Nate. I wish you the best in your pursuit of the perfect dash lights. Hope the LEDs work out for you. Make sure the stock socket voltage will work with your LEDs. Using relays to switch LEDs is sure to work, but is less energy efficient. Using transistors to switch LEDs could be asking for trouble unless you know about transistor calculations. You may end up needing to calculate currents and resistor values for the various transistor terminals. You want them to function in the cutoff and saturation regions only. An N-type transistor will activate when a voltage is applied to the base/gate that is higher than the threshold voltage. A P-type transistor is active when the base/gate voltage is lower than the threshold voltage.

Nate

Austin, can't use white LEDs because when filtered they don't come out the correct color. Taking apart the car is pretty easy... its just getting the damned dash off... you have to pull really hard!

Bebber, yeah I hope to use the same sockets. The stock bulbs have a neat way of fitting in their plastic base. In fact, I can rip the bulbs out and put LEDs in their base! This way my LEDs would snap to the PCB just like the bulbs. I think I can do this even if the bulb power is different than the LEDs. Anyway, the leads coming from the bulb simply wrap around the base to provide contact with the PCB when the base is snapped in.

I went out and bought a digital multimeter this morning... you might get a kick out of this. I'm so ****ing stupid I thought I knew how to use the SOB before reading the manual... I had the settings right but the positive test lead plugged in the wrong hole (theres 3 holes depending on what you're measuring). Long story short, touched the leads to one of the 6mm holes in the AC panel very briefly and kinda, heh, turned the tops of the wires on the PCB around the bulb hole a slight brown. Everything still works and ****, just a stupid mistake that fortunately didn't hurt anything.

I RTFM and took another reading: 10.7 volts. I'll get more complete readings on all the bulbs later tonight. I'm doubt I'll find any LEDs that run off 11v... the ones I've seen are 3.6v, 5v, 12v, or 14v+. And the ones over 3.6v are too expensive. I might be able to get tricky and put a resistor right before the LED and still have it use the stock bulbs base... we'll see.

Nate

As I said, 14v LEDs are too expensive. Also as I already said , the blue filters don't come out. They are a part of all the components.

As for white LEDs, they are made by taking a blue LED and putting a yellow phosphorus coating on it. Since there is very little red and green in the light giving off by a white LED, you can't just use a colored filter...



...however, it'd probably work with a blue filter but why take a blue LED coated with yellow phosphorus (ie, a white LED) and shine it through a blue filter to make it blue again? Besides, the advice I've seen is to "maintain accurate and brilliant colors, it is imperative to match the LED color with the lens color", so at least we don't have something wierd like light green colored filters!

On a side note (I'm talking about footwell lighting again!), I wanted a strip of light tape for each passenger's feet but the kit only came with enough extra connectors to make 3 strips. I found some connectors at Radio Shack that will do perfectly! Also my indiglo pedals should be arriving between Wed and Fri... looks like I'll have both these (footwell lighting + pdeals) in this weekend! Don't worry the pedals are pretty tight looking, not those ghetto ones you see. Of course if I don't like them when they come, I won't put them on. I'm actually not sure the footwell lighting will look good so I may wait on that.



Blue pedals, blue dash/radio/switch lights, blue footwell lighting, blue indiglo gauges...!

bebber

Austin, I guess I might have midjudged you too. Looks like we're generating some good ideas here on the forum.

Nate, here's some more tips on LEDs.LED's should be operated with a resistor to help limit the current flow, or the LED will burn out after a minute of operation. As you know already, it's ok to give an LED less voltage than per its specs, but giving it more voltage is a bad idea. You can decrease the voltage of the sockets to a lower voltage by using two resistors. Connect one terminal of resistor1 to the +10.7v side of the socket. Connect the other terminal of resistor1 to one of the terminals of resistor2. Connect the other terminal of resistor2 to the ground connection of the socket. This should form a complete circuit loop. The voltage at the point between R1 and R2 will be V=(Vtotal*R2)/(R1+R2). So if your Vtot=10.7v, R1=2Kohms, R2=1Kohms, then your V at the point in between the resistors will be 3.56V. You can connect the positive terminal of the LED there and the negative terminal of the LED at the ground of the socket. Note that the voltage at that point will change once you connect the LED, so you may need to add another resistor in series with the LED or increase R1.

Nate

Well, as bebber mentioned, using the power currently going to the stock bulbs to power the LEDs would be most efficient. Also I wouldn't have to **** with relays, running power wires, or mounting the LEDs where they should go. I checked all the bulbs and they are 10.7-11 volts... I'm sure its a safe bet they are all 12 volts. Since to measure amps you have to put the multimeter in series, I measured ohms and used I = V/r (assuming 12v) to figure amps. Here are my findings (sizes are of the holes, not the bulbs):

AC panel:
6mm x 5 - 35 ohms, 0.34 amps
5mm x 4 - 16 ohms, 0.75 amps

Cruise control switch:
4.5mm x 3 - 20 ohms, 0.6 amps

Sunroof switch:
4.5mm x 2 - 35 ohms, 0.34 amps

Heated seat switches:
4.5mm x 6 (3 in each) - 39 ohms, 0.3 amps

Hazard light switch:
4.5mm x 1 - 24 ohms, 0.5 amps

Shifter:
6mm x 1 - 12 ohms, 1 amp

Clock:
5mm x 1 - (didn't take a reading)

I will have to somehow disable the radio LEDs since they are soldered to a PCB... maybe desolder them? Maybe they unplug but I doubt it (I pulled pretty hard already hehe). Then run my own LEDs in there... gonna be a ***** but worth it.

Anyway, the little clips holding the bulbs in can easily be repurposed to hold my LEDs. You just slip the LEDs in and bend them over. When the clip is mounted in the PCB the leads touch the contacts. The leads are bent in such a way that they are exposed on the top of the clip before they touch the PCB contacts. I'll try and draw you guys a picture. I'm not worried about the work soldering on all the resistors, but the clips are small and plastic and I don't want to ruin them. After looking at my horrible pic , do you think it would be better to reuse the clips or run my own power and use relays?



Also I was thinking today... I'm gonna have blue gauges and lights, but green ass blinkers! So I uninstalled my gauges and found that the only thing making the blinkers green is a thin green filter. I plan on going out and getting some blue translucent material ASAP! Any ideas on what I could use? Heres a pic:

NighthawkBlack

OMG! We've started a nerd forum! LOL

Just kidding, all those ideas seem really good. Good luck with the work Nate. Lots of people say some mods aren't worth it but I think they just feel bad because they won't or can't put the effort i to do it! I know how you feel driving without all those parts. I did it for a month while I was working on some of my parts.

Austin519

Heh, d@mn Nighthawk found us! Aaah!

Nate:
Yep, the direct LED wiring is best...but for the last time...get some potientiometers to adjust the voltage drop across the LEDs...1 amp POTs should be fine for everything. As for the translucent material I have two ideas...get the blue saran wrap (cheap solution) or go to a lighting place for theaters and get the colored plastic inserts they put in show lights and cut it to your specs. As for the radio LEDs...I'd just desolder them...however scary that sounds...or you could go grab that good ol blue saran wrap again and wrap em. It works, I've tried it...and that'd keep you from doing permanent damage to the radio.

You also may want to be more accurate on that current measurement for the shifter light especially...since it's right on the 1 Amp mark...go measure resistance, then measure voltage (parallel, touch either side of the LED) and then use I=V/R.

I can't tell crap from your pic But I will say...running your own power to EVERY LED will suck...and the transistors/relays will give off heat, and will introduce EM noise into the car...I'd just use what's there if I were you...I'm not sure what you mean by clips...I assume you mean a power-socket type thing...in which case just use taps to tap into the wires running the the socket and run your own...bypass the socket completely...

Austin519

Guest

After you are through with the blue interior lighting are you planning on perhaps making a kit with all the LEDs instructions etc available for forum members? I think a LOT of people on this board would be willing to shell out a reasonable amount of money to get the blue dash/console/door lights in their car. I know I would. Something easy to install for people to have someone else do the install (labor cost) and a package of plug and play parts would be something to think about as you decide the final method you will use to finish this project.

Nate

"get some potientiometers to adjust the voltage drop across the LEDs"

I don't see what the difference is if I just bought the correct resistors.

"As for the translucent material I have two ideas...get the blue saran wrap"

Not sure its going to be dark enough... the green filter is quite dark (can't see through it at all, have to hold it to a light to even tell its translucent). I'll go to home depot tonight and see what I find.

"As for the radio LEDs...I'd just desolder them...however scary that sounds...or you could go grab that good ol blue saran wrap again and wrap em."

You forget the radio LEDs already have blue rubber condoms. They are yellow + the condom = light green. Saran wrap won't help. Probably have to desolder them (wonder if I could find a shop, or my uncle hehe, to do it for me) and hook up my own power.

"You also may want to be more accurate on that current measurement for the shifter light especially...since it's right on the 1 Amp mark...go measure resistance, then measure voltage (parallel, touch either side of the LED) and then use I=V/R.

Thats what I did. It was something like 11.6-12 ohms and something like 11.3-12 volts. I don't think it will make to obig a difference. I hope to put the big fat $10 5V LED there anyway.

"I can't tell crap from your pic But I will say...running your own power to EVERY LED will suck...and the transistors/relays will give off heat, and will introduce EM noise into the car...I'd just use what's there if I were you...I'm not sure what you mean by clips...I assume you mean a power-socket type thing...in which case just use taps to tap into the wires running the the socket and run your own...bypass the socket completely..."

I have to run my own power for the radio LEDs.

Ok, about the clips, listen carefully. There are clips that hold in the stock bulbs. They go in a hole in the PCB and are given a 1/4 turn to lock in place. The way they work is the leads from the bulb come out the back of the clip and wrap around. The leads touch the PCB contacts when you give it that 1/4 turn. Check out my pic again:



On the left are 3 different crappy drawings of the stock clip and stock bulb. See how the leads come out of the bulb and out the back of the clip, then they are wrapped around the edge of the clip so they can make contact with the PCB? Then the diagram on the right shows how I'd reuse the clip with my LEDs, with a resistor inline.

Maybe this will help...



This shows one of the leads and how it comes out the back and wraps around the clip. The arrow is where the PCB would make contact with the lead.

These things are small and plastic so soldering might be kinda hard, but reusing them would solve the problems of how to keep the LED in the hole where it is supposed to go, and also how to tap into the power that the stock bulbs are currently running off.

Get me now? What do you think?

Nate

That might not be a bad idea, though all the time its going to take to solder on resistors might not make it worth my while. Plus dealing with things like desoldering LEDs from your radio is a daunting task! The parts for me to build a kit would be something like this: 35+ LEDs - $40+, 35+ stock bulb clips (if I can even get them) - $50+?, time spent soldering resistors - priceless (hehe)...

Really this is an easy project... once I'm done you'll know what and how many LEDs and resistors you need to get and how to attach them. Then you just need to dismantle your car (very easy, few screws, couple clips, some patience, and some guts ) and put em in there. The hardest part is figuring out what to put in and how to put it in. My 6 LEDs still having gotten here... once I get them and decide which to use, I have to put in another order and wait another week for them to ship them to me... Meanwhile my car is all taken apart!

daverman

OK, let me see if I can shed some light on the subject (no pun intended).

Nate: you can't figure out how many amps a bulb is going to draw by simply measuring its resistance when it's cold. The best way to do it is to look at its wattage (power) rating. Remembering P = VI (for DC), the current drawn would be I = P/V. For a 1 W bulb, for example, the current drawn on a 12 V DC line would be 1/12 A, or about 83 mA.

The reason you put resistors in series with LEDs is that LEDs are diodes, and will maintain a certain voltage drop across its terminals no matter what. If you force the voltage across an LED to higher than its natural drop you're going to bust the bulb because it will draw a lot of current.

What you need to adjust is the current going into the LED. Most LEDs take anywhere from 20 mA (regular LED) to 80 mA (white LED) for maximum brightness. Check your LED data sheets if you need guidance.

Let's say your LED has a 2V drop across the terminals. If you want maximum brightness at 12V, you need to supply 20 mA of current into it. Since R = V/I, the series resistor you need is R = (12 - 2)/0.020 = 500 ohms.

Nate

"you can't figure out how many amps a bulb is going to draw by simply measuring its resistance when it's cold. The best way to do it is to look at its wattage (power) rating."

I don't have wattage ratings for these bulbs. Why is taking the resitance when its cold not accurate?

Say my power is 12v and 0.34 amps, and say I have an LED that is 5v and 10mA... what resistor do I need? Atleast I think thats the specs on the LED... heres the LED specs in question:

<TABLE border=1 cellSpacing=0 height=61 width="100%"> <TR> <TH bgColor=#c0c0c0 height=50 rowSpan=2 width="21%"><FONT face=Arial><SMALL>LED<BR>Color</SMALL></FONT></TH> <TH bgColor=#c0c0c0 height=50 rowSpan=2 width="14%"><FONT face=Arial><SMALL>Lens<BR>Color</SMALL></FONT></TH> <TH bgColor=#c0c0c0 colSpan=3 height=18 width="41%"><FONT face=Arial><SMALL>Electrical-Optical Characteristics<BR>(Ta = 25°C)</SMALL></FONT></TH> <TH bgColor=#c0c0c0 colSpan=2 height=18 width="14%"><FONT face=Arial><SMALL>Chromaticity<BR>Coordinates<BR>t yp</SMALL></FONT></TH> <TH bgColor=#c0c0c0 height=50 rowSpan=2 width="11%"><FONT face=Arial><SMALL>Full Viewing Angle</SMALL></FONT></TH> </TR> <TR> <TH bgColor=#c0c0c0 height=28 width="51"><FONT face=Arial><SMALL>If = mA<BR>typ/max</SMALL></FONT></TH> <TH bgColor=#c0c0c0 height=28 width="27"><FONT face=Arial><SMALL>lv mcd<BR>typ</SMALL></FONT></TH> <TH bgColor=#c0c0c0 height=28 width="41"><FONT face=Arial><SMALL>Vf = V<BR>typ/max</SMALL></FONT></TH> <TH bgColor=#c0c0c0 height=28 width="30"><FONT face=Arial><SMALL>X</SMALL></FONT></TH> <TH bgColor=#c0c0c0 height=28 width="30"><FONT face=Arial><SMALL>Y</SMALL></FONT></TH> </TR> <TR> <TD align=middle bgColor=#ffffff height=0 width="65"><FONT face=Arial><SMALL>SP Blue</SMALL></FONT></TD> <TD align=middle bgColor=#ffffff height=0 width="28"><FONT face=Arial><SMALL>W Clear</SMALL></FONT></TD> <TD align=middle bgColor=#ffffff height=0 width="45"><FONT face=Arial><SMALL>10/25</SMALL></FONT></TD> <TD align=middle bgColor=#ffffff height=0 width="22"><FONT face=Arial><SMALL>130</SMALL></FONT></TD> <TD align=middle bgColor=#ffffff height=0 width="41"><FONT face=Arial><SMALL>4.8/6.0</SMALL></FONT></TD> <TD align=middle bgColor=#ffffff height=0 width="31"><FONT face=Arial><SMALL>0.13</SMALL></FONT></TD> <TD align=middle bgColor=#ffffff height=0 width="29"><FONT face=Arial><SMALL>0.075</SMALL></FONT></TD> <TD align=middle bgColor=#ffffff height=0 width="39"><FONT face=Arial><SMALL>160°</SMALL></FONT></TD> </TR> </table>

What does all that mean? If = mA? Vf = V? Chromaticity Coordinates? lv mcd?

I guess we'll see your LED kit right after you get the gauge needles off, eh Austin?

I think I'll give reusing the power and clips a shot. And I'll stop by an art store tomorrow and pick up a blue filter for the blinkers. By this weekend I should have blue footwell lights, pedals, and blinkers!

daverman

Because a light bulb changes its resistance when it glows.


Don't worry about the power of the bulb you're replacing. Your LEDs are going to take nowhere near the power of that bulb.

I'm going to take a guess on the table notation here:

If = current draw at maximum intensity (10 mA typical, 25 mA max)
lv mcd = luminance in millicandelas (130 mcd typical)
Vf = voltage drop (4.8 V typical, 6.0 V max)
Chromaticity coordinates tells you the X-Y coordinates of the bulb's color temperature in the CIE chromaticity chart (picture and explanation).

OK, using the typical values of 10 mA current and 4.8 V voltage drop, your series resistor should be approx. R=V/I = (12 - 4.8) / .010 = 720 Ohms. There are cheap standard (10%) resistors with 680 Ohm values, which should work just fine.

Remember that you need one resistor per LED, like this:

daverman

By the way, have you checked out www.ledtronics.com? They've got really cool LEDs.