LED strips

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boardsportsrule

[H]ard|Gawd
Joined
Nov 27, 2003
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hey, im gonna pimp my ride out some what....im thinking of geting some 1" acrylic tube from usplastic.com and cutting about 1/4'th of an inch off...then in that flat section drill holes for LED's..then mount it under my car....BAM! nice glowage! wooot..any who i gots a couple Q's..

1) how can i make it so that its only on when the cars on? i think i remember something called a relay doing this, what is it and how would i wire it?

2) i assume ill just run this from the 12V car thing... ill figure ill just take the dash out and take the power from right before the cig ligher, or where ever that gets it power, if i can find that...and problems with that? is that pretty steady voltage?

3)how often should i pop a led in to keep a contstant glow? i was thinking one inch, but that would be ALOT of soldering and stuff...

any who, whatcha yall think of this, any possible problems??? i've got my self a green ford explorer...1994, thinking of popping some greeen LED stick under, i think it should look hot....my friend who is gonna buiy this tan explorer wants me to make him an or=ange strip if this looks good..should be a sick/cheap/DIY/fun way to make your car pimped out :)
 
buying hundreds of LEDs and resistors and wire, milling the acrylic tube flat, etc... will cost a decent sum of money and will take a lot of time to do.

Also, how do you plan to insert the LEDs into the holes from inside the tube? :D

"real" undercar glow kits aren't that expensive, and they're designed so that they're protected from water/corrosion/etc.
 
well actually it's quite cheap...ressitors are dirt cheap, i can probably get 300 of them for under $5...LED's are quite cheep in bulk from ebay.com, like 15 for 100.... then plexi tubes are 4.14 for 4', i prlly need about 4' on each side....all other electrical things are already purcahses(Except relay) so im looking at right around $30...and DIY is so much better then premade....im all about the DIY :)
 
actually there are led style underbody kits that you can get for cheap and they have programmed boxes to have chasing lights (like knightrider) and other pre-programmed lighting desgins.
 
yep...i dont care, those are lame, i cannot claim i made them then... i dont care if its the same price, hell even a little more...i dont wanna buy one, with need effects, i want to make them, and have my own switch on there to control the sick on and off effect. i dont want chasing, i dont want knight rider, i want on and off and i want to make it.... i dont know why this is so hard to understand...any who if you cannot help me with the questions i posted i would apprecciate it if you could keep quiet...
 
Who cares if you made it or not? Its on your car where NOBODY'S gonna see it, except the light it gives off.

Besides, why put that much $$$ into something that's gonna get you a ticket? Decoratve lighting is illegal in just about every state in one way or another. Here in PA, they make you take it off in 10 days, and you have to go to court to prove you took it off. Yes, the judge actually comes out and looks.

Get yer ass down to PepBoys, spend the $$ and buy a premade kit. If you don't know what a relay is, or how to wire it CORRECTLY to your car, then you'd save yourself a lot of hours by buying one that is premade.
 
gee said:
buying hundreds of LEDs and resistors and wire, milling the acrylic tube flat, etc... will cost a decent sum of money and will take a lot of time to do.

Also, how do you plan to insert the LEDs into the holes from inside the tube? :D

"real" undercar glow kits aren't that expensive, and they're designed so that they're protected from water/corrosion/etc.
Click to expand...
ps, re-looked at this, got a couple things... my design is layed out below.. then ill get a hellofalot of heatshrink and cover all solder joints up...if i purchase 10+' of heatshrink i should be good... its fine if water gets in there, just not rust...

tube layout.bmp
 
wow, i guess all the spirit here is lost...thought you people liked doing DIY stuff, and helping others...

i know what a relay is, i know how it works, but im not sure how to put it into a car, as i rarely work with cars...im not sure where to find power lines that are active only when car is on...

as for the money thing, its not gonna cost more then $50, http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7980732526&category=33713
same price, except mine does what i want, without all that extra junk, mine will be home made, mine will give me pleasure in making, and mine will be alot longer and brighter...hmmm who's solution should i go with? mine..thanks...


ps. why do i wanna make it when no one will see it except for the light? because, it's fun, and when people ask where i bought them i can say that i made them, which always is funner for me to say rather then something lame like pep boys...
 
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To answer you question...

If you wanted to make it automatic, you could wire the relay coil to the radio power. So the lights would be on when the key is on. Or you could wire the coil to the parking lights so that when the parking lights are on, so is your light bar.

What I would probably do is to just get a small toggle switch and put it somewhere in (or under) the dash that would control these lights, then you could just pull power from the battery. You'd just have to remember to turn them off, but the leds don't draw that much current (if you don't have too many) so it may not hurt anything if you forget now and again.

That would be a wiring nightmare as you'd have _many_ series/parallel circuits, but if you did your series circuits right, you could get away with not using resistors, so it wouldn't cost as much...

Good luck!
 
how are you going to cut acrylic with a table saw? It will all start to melt a couple inches in.

And unless you get ultra-bright LEDs, your lighting is going to be super dim regardless of how many LEDs you get.
 
xtant3150- thanks alot, :) answered my Q's and gave me ideas for the relay.... finally a usefull post!

jojo- maybe most do, but the one i have been using doesnt melt it..... used to to make many cuts before, never had a problem
 
Alls I gotta say is "Post pics when you're done."

I think it's great that you wanna do this yourself. But, there are times when buying something is better than making something. This is definitely the case. Remember what I said...as soon as the cops see it, it's coming off. Why waste the time to build it if you'll only get to use it a week or so? Decorative lighting is the quickest way to get pulled over, since its so aeasy to spot "the car with all the lights on it" and it stands out in the crowd.

Funny how all the stuff you do to your car to make it stand out (for good reasons) is also what makes it stand out in a bad way too.
 
boardsportsrule said:
jojo- maybe most do, but the one i have been using doesnt melt it..... used to to make many cuts before, never had a problem
Click to expand...

do you know what type of blade you use? thickness? I could use something that cuts acyric, right now I have a special knife that I score with and break, its great for straight cuts on sheets but I'd love to be able to cut circular rods such as yours. I've cut PVC pipe in half just fine, so I don't think its my technique...
 
why would it be illegal, i heard that too, but it just seems stoopid! ill have a switch so if they bitch about it ill just turn it off... and then when i pull away turn em back on :p

as for the blade and stuff, not sure, the table saw i used at school is what i use, and i dont have access to that now, if mine at my house doesnt work i can get into the school... im not sure what size the blade was, but it was in the wood shop so it wasn't a metal cutting blade, just a wood one... slow and steady!!
 
To cut plexiglas/acrylic, I've found a panel blade (thin blade, small teeth) works quite well.
 
About resistors, you definitely want to use them. A car's voltage is not stable, and if you don't use resistors then current increases exponentially as you go past the rated forward voltage of the LED. It probably won't kill them instantly, but it will definitely shorten their lifespan. You could even use a voltage regulator or inductor to further protect your LEDs from voltage spikes, since with a resistor the current will still increase linearly with a voltage spike. Since your wiring, if it's anything like mine, will be jumbled, making your LED's last as long as possible will prevent the need for time consuming replacement of LED's.

Resistors are amazingly cheap so there's no point to skimp on them, except on account the time it takes to solder them up. To speed up soldering, you might consider putting all of the parallel resistors you use for each series combination of LED's on an etched PCB, then connecting your LED's to it with wires. It should be simple enough that you don't even need a CAD program, you can just use a sharpie to draw the design. Or if you want to be even slicker, you could put a two pronged connector on the board and the string of LED's, making assembly and switching out a damaged string a breeze.

As for the legal aspect, having odd lighting on your car is a distraction to other drivers. That's why it's illegal in many places. So play it smart and don't try to distract other drivers with it. And don't be a bitch around cops by turning them back on after you leave. If not only because it's a rather petty attempt at rebellion, but also because if they catch you doing it you can be sure you won't get another warning.
 
will the votage coming from the cig lighter be jumpy too? i was planning on goin thru cig lghter if possible, but if i dont get the benefiet of steady voltages i could just use 4 1A regulators.... 1 for each bar...i planned on doing a 1:1 resistor to led ratio...one for each...it'll be a bitch to solder but in the long run it should be easier....clost to 200 solders ill have to do :( ...planning on doing 98 LED's, one every 2" or so..


as for the legal thing that kinda makes sense...thats to bad tho :( o-well, ill be nice :)
 
Allright I have had the neon variant of these on my car for about three years I had them in the bright green color to match the paintjob of my car and here are a few tips:

1. Wire it straight to the battery (fused close) and put a master switch somewhere in the cab, I also had a switch for the front, back and each side, so I could controll them independantly,

2. As for mounting them I recomend going to the hardware store and buying a length of foam that is used for wraping PVC pipes in the same diamater of the tubing you are using and metal hose clamps a 1/2 or so biger than than the OD of you tubing, To attach the tubes to your car cut a piece of foam off and place the hose clamp around the foam (the foam prentens the hose clamp from sliding around and cutting in to it for vibration). tighten down the hose clamps so that they are firm enought to hold it in place with out crushing the tubing, to hang the tubes drill a hole into the body or frame of the car and screw through the "tail" of the hose clamp it hold like a charm and has never failed me, (the bulbs broke long before the hose clamps.

3. As for the legality of the lights I live in Tulsa Oklahoma and I have been pulled over many times but never for the lights, ((it does make you more noticible when speeding) and never once have I ever had any problems from the lights most cops ask me questions about them, In Oklahoma the only colors that are illegal are those colors reserved for emergancy vehicles ie. red and blue, so your good don't listen to anyone who has never had these, but I would advise you call your local police station and ask them what color lights are banned on vehicles as well as the legailty of under car lights usually as long the dont impare the vision of other drivers they are allright.


Good luck
 
sick! glad to hear some one else has done this! what did you use to put the LEDs into? and are you reccomending the insulatior and clamp for where i mount it? how would insulation and zipties work? i was thinking either pink or green(i have a green car, with a pink and black rack on top) so i wanna highlight those colors... maybe even UV purple or something.... thanks alot for the help! greatly appreciated from some one who has done this:)
 
Well I didn't actullual build the light bars myself I bought the neon lights that go underneath before the LED light bars came out, The only thing I built was the brackets, becuase the ones that shipped with the lights were plastic and became brittle and started braking. I would stay away from zipties.

As for the clamps and insulation you only need one every foot or so and they are just for mounting the tube to the car, Sorry I dont have any advise for actually building the light part.
 
OK, a few tips here.

1. Wire it to the "Accessory" bus on the car. There should be a fuse in the fusebox labeled this. This is the power that goes to accessories that are powered on with the car and off when it's off. Also include a switch on the dashboard for control in case "the man" wants you to turn them off or you just want to be a bit less obvious.

2. A voltage regulator is a good thing. It can also be used as a current regulator, and since LEDs are current devices, this is a good thing. If I were you, I would use several parallel "strings" of 4 to 6 LEDs in series (depending on their voltage drop, which is dependant on many factors including color, check with the seller). Multiply the voltage drop times the number of LEDs you want in the string. Try to get it as close to 12 without going over. This will be the number of LEDs in series in each string. Multiply the number of strings times the normal current draw (15 ma is usually a safe number, again check with your vendor) to get the total current usage. Use a LM 317 regulator in this circuit to give you a constant current regulator:

Reg3.gif


Replace the variable resistor with one where R = 1.2 / current.

For example, if you have a 4' long bar with LEDs every inch, that will be 47 LEDs. Let's eliminate one on each end to provide space for your clamps (the above idea for clamps and foam is a good one). If you use series strings of 5 LEDs, you'll have 9 strings in parallel. At 15 ma each, this is a total of 135 ma for each side, for a total of 270 ma ( 0.27 amps). Putting this in the above formula, you get R= 1.2/0.27 = 4.5. You'll probably be fine using anything between 4 and 6 ohms. Or you could be a little safer and make one regulator for each side and use twice the resistance in each.

You could substitute a LM7812 for the LM317 and use the formula R = 12 / current instead.

3. You'll want to sand the bottom part of your acrylic rod and possibly flame polish the flat part, if you've got the skills. Light primarily escapes from the opaque sanded portions. The shiny parts tend to reflect light internally back into the acrylic and you would only have light escaping the ends and the flat cut part.

4. Cutting Plexi/acrylic requires a sharp blade with a high tooth count, probably around 80 for a 10" saw.

I've built LED running lights, turn signals, and brake lights for my motorcycle, so I've done this before
 
hey, more info!:) so what would be the advantage of that over justtaking the 12V from teh fuse box(from accessories) and use 470OHM resistors on each Led? i would assume the electricity from the fuse box should be pretty stable. assumeing i did use the regulator, would i have to do anything to bring the electricity down to a certin votage, or will controlling the current alone be enough? thanks! much appreciated :)
 
The voltage in the car's electrical system will vary from about 11v (engine off) to about 14v (engine on). This is due to the battery being 12v, but under load (and added resistance from long wire runs) it could sag a volt or two. The alternator generates 13.8v because you need the extra voltage to charge the battery up to it's nominal 12 volts. The regulation on alternators may not be exact and can sometime go up past 14v.

Lots of resistors would be inelegant and would probably take up lots of space. Plus it would waste .17 watts per LED. That's not much, but it adds up with lots of LEDs.

The current regulator should be sufficient, and will be unaffected by voltage (unless the voltage drops below the summed voltage drop of the "string" of LEDs, but that's why my design added a little headroom. The "string" allows you to use muliples to utilize the voltage instead of lots in parallel which might need too much current.
 
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