LED light making

[WallacE]

OK so here's the plan:
I have been looking online at light kits and they range from 40-100...So I was thinking is there a way to make your own LED light kit that takes less money but a lot of time.

Basically I am not currently working so I have plenty of time but not a lot of money. I am looking for any tips/advice on how to go about this adventure. I am not too electrically savvy but love the thought of DIY projects. So if anyone can point me in the right direction as to local places to get LED lights wiring ideas that would be great.

I guess if you think it is best to just buy one let me know that too, but I figured since I have plenty of time on my hands DIY would be the best way to go.

Thanks

PS-I am wanting to do white underbody lights.

[Trackerrrr]

Radio Shack. They got drawers full of the things.

[Wild-Bill]

I was looking at that last year, thinking about replacing all my instrument lights with LEDs. Like you, I'd rather do my own work. Start by looking at how many lights you want to run and how bright you want them. It makes a big difference in price whether you're looking at high intensity LEDs or standard ones. The lights themselves are going to be the biggest part of your cost.

Next, you need to figure out the power draw. Since you're basically thinking about running a string of lights, you want to run them in "parallel", meaning that the same voltage goes to each light and if one burns out it won't take out any of the other lights. (If you're not sure what "parallel" circuits look like, think of a set of railroad tracks. The rails are the wires and the ties are the LEDs. Each LED gets the same voltage down the entire length of the circuit. current is split evenly.) With that in mind, multiply the wattage of your intended LEDs times the number of LEDs on a pair of wires and there you go. That's going to tell you how much to spend on the "current limiting resistor". The higher the wattage, the pricier the resistor and, oh, the more limited you'll be in resistance values available at the necessary wattage. You may have to do some compromising when building the power filter in terms of putting several resistors together in a combined serial/parallel network to get the desired total resistance.

OK, so you know the required wattage (actually, you're looking at the Amperage in mA for the calculator) and voltage for the LEDs you want to use (from the spec sheet) and the number you plan to run in parallel. Take that info to the handy-dandy calculator at http://ledcalc.com/#calc to help out. One thing I discovered about the Rat Shack is that the LEDs they had in stock never quite matched the ones on the website. It helped to bring the address of the LED calc with me and re-adjust once I saw what LEDs the store had in stock. Generally, you can usually find a geek working (or shopping) at the store who'll help you figure out how to wire the resistors to get your desired power setup. (If they take a lot of time helping you buy them a smoothie or a new pocket protector.)

Example:
Using Radio Shack LEDCatalog #276-017 ($1.99/2 LEDs)
---- Power draw: 25mA, 3.3V
Let's say you want to run 2 strings of 20 lights each. Calculator says you'll need a pair of 5W, 18ohm resistors. (One for each string. Makes the math easier and keeps each string independent of the other.) Radio Shack doesn't stock them but they do have 10W, 10 ohm resistors. With a pair of them in series (wired end-to-end) you get 20 ohms. A little playing with the LED calc shows that this will give you between 3.0 and 3.1 volts drop across the LEDs which should be more than good enough.

Now look at the total project price:
40 LEDs @ $1.99/pair=$40
4 resistors (RS Catalog #271-132, 10ohm resistor, run 2 in series to get 20 ohms per string) $4
Project Box (RS Catalog #270-1801) $2.29
Breadboard (RS Catalog #276-148) $1.99
Wire, solder, shrink wrap, connectors, etc. $5
Total: $53.29 + Labor and Time - satisfaction of doing it yourself

How much is the pre-assembled kit?

[Black_peter]

Radio shack?!?!
That's like buying groceries at the gas station.

http://katriders.com/vb/showthread.php?t=55985

I have made turn signals, tail lights, brake lights, gauge back lights, licenses plate lights.... No headlights though

[WallacE]

So would it be cheaper/better to solder in a resistor for each bulb. I saw on yours Peter that is what you did and you said those cost "pennies a piece".

Like I said I don't care how much time it takes, just at seeing if I can do it cheaper than buying a kit.

The way I figure it the kit is going to cost about $75 for an 80 LED kit, which the LED's are in "PODS" and the pods are ran together and mounted to your liking. I like the idean of drilling holes in the fairing and having nothing but a little bulb pop out. I think that it would look a lot cleaner and be different than everyone else.

[Black_peter]

So would it be cheaper/better to solder in a resistor for each bulb. I saw on yours Peter that is what you did and you said those cost "pennies a piece".

Yeah you buy resistors in strips, I think I got a 100 for $6.
I use one per LED because if one resistor goes out then only one LED goes out. In the case of tail lights etc, I don't want to lose my tail light if a 6 cent resistor goes out. I got a good deal on some LEDs off eBay last year.

[MrBrant]

Another couple tips:

In the LED datasheets (yes, look up the datasheet for the specific LED you have), there are usually 2 different sets of parameters: "Absolute maximum ratings" and "operating paramaters" or "Electrical characteristics".

1. Stay waaaay the f*** away from the absolute maximum ratings. If the absolute maximum rating says 30mA, don't go above 20mA as a general rule (and use 15V as opposed to 12v in you calculation).

2. be sure you're looking at the "steady DC current" not the "peak pulse current". your turn signals aren't "pulse current" (which is usually measured in micro seconds, and a very low duty-cycle).

3. Don't use trial-end-error whne you hook them up so that you hook them up backwards by mistake. Obviously since they're diodes, they won't work, but (more importantly) LED's can only handle ~5V reverse voltage before causing damage. Even if they work again once you've changed the polarity, you're probably looking at a much shorter life.

4. Make sure to get ones with the automotive operating temperature range.

oh, and Take pics!

[BigFish]

There are some things you can do to make this much easier. First shop around. Ebay and the internet are your friend here. $40 worth of LED's from Radio Shack will cost you $5-$10 elsewhere. Keep in mind that many "yellow" LED's are actually green. Whenever possible get the color temperature and use that to determine the actual color of the LED.

As for the resistor you can get away with wiring them in series IF you wire multiple resistors in parallel. If the required resistance is 100 ohms then you can take four 400 ohm resistors wire them in parallel and you'll get the equivalent of a 100 ohm resistor. The catch is that if one resistor burns out you'll only have 3 functional paths; if one burns out you'll have 133 ohms resistance (2=200 ohms, 3=400 ohms). In other words it will still work if one burns out, but it will be dimmer. If you do this make sure you place the resistors so that they are not touching since they put out heat and this is the main cause of failure in resistors.

[WallacE]

http://cgi.ebay.com/New-50-white-10MM-LED-light-Lamp-12V-DC-Free-Resistor_W0QQitemZ160346314979QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item25556298e3

Found this...looks like it comes with 50-10mm LED's and 50-Resistors...does this look like a good deal or what I need?

[Black_peter]

Sure, go for it.. That was just the kind of site I got mine from.
I haven't duty tested them, I took a sample led from the ones I got from superbriteleds.com I hooked it up to 12 volts and let it run for 3 days.

You could try that with these. Figure if you get it to run for a week without fail it ought to last a riding season...

[Wild-Bill]

Radio shack?!?!
That's like buying groceries at the gas station.

No, that's like buying groceries at the grocery store. You're just used to Costco.

No question that if you know what you're looking for you can find it cheaper elsewhere. There's a reason why I call the place Rat Shack. They're never the cheapest but they've got what you need for a small project and they hire geeks who can explain things to you. Not a bad way to get an education...

[Black_peter]

No, that's like buying groceries at the grocery store. You're just used to Costco.

Nah, I'm an engineer who knows a 500% mark up when he sees it.

[Astro4x4]

I buy my loose LEDs off some outfit on Ebay from Hong Kong - way, way, way cheap and all good quality.

[Wild-Bill]

Nah, I'm an engineer who knows a 500% mark up when he sees it.

Translation: You're one of those folks who paid big bucks and spent lots of time getting a WAY better education than the rest of us!

[cmurdah]

OK so here's the plan:
I have been looking online at light kits and they range from 40-100...So I was thinking is there a way to make your own LED light kit that takes less money but a lot of time.

Basically I am not currently working so I have plenty of time but not a lot of money. I am looking for any tips/advice on how to go about this adventure. I am not too electrically savvy but love the thought of DIY projects. So if anyone can point me in the right direction as to local places to get LED lights wiring ideas that would be great.

I guess if you think it is best to just buy one let me know that too, but I figured since I have plenty of time on my hands DIY would be the best way to go.

Thanks

PS-I am wanting to do white underbody lights.

i bought some 5mm blue led's off of ebay about 2 years ago. they came from hong kong, took about 2 weeks to ship in. think i got 25 of em for 3 or 4 bucks, shipped. as soon as they came in, i hooked 8 of em up in my car behind the vents. 2 years later, i flip the switch and they still burn. ive probably put 10000 miles on the car with the lights burning.

just my .02