Instructables
Picture of Motorcycle LED Tail Light
If you've been thinking about building an LED tail light for your motorcycle - or any other vehicle - then you need to read this guide. Why? If you're trying to figure out how to do it than you probably have already figured out that LEDs are super bright, turn on and off way faster than incandescent bulbs, and are generally awesome.

Here are a few things to consider before beginning this project. You need to ask yourself if you're up to the challenge. If you have a lot of electronics/soldering/circuit design experience then this is probably pretty simple of a project; however, if you're anything like me I didn't realize how much work I would be doing. Is there any other way to go about achieving the same results? In retrospect, I kind of wish I had just spent the same amount of money to buy an automotive LED tail light off of Ebay and then modified it to fit in my motorcycle's tail light housing.

There are some decent sources out there and I'm certainly not the first person to try and do a build like this but my reasoning behind writing up an instructable is to compile a few of the things that I learned and maybe help make the process easier for someone else who is trying to achieve the same thing.
 
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Step 1: What do you need?

Picture of What do you need?
Project Cost = Approximately $50. This will depend a lot on if you have any electronics/soldering supplies on hand, if youre willing to order parts online or if you are content forking out more money to buy from RadioShack.

Parts List:
LEDs - $15-$30
Prototyping Board or Perfboard - $5 RadioShack
Solder - Hopefully you already have some.
Jumper Wire - Scavenge if you don't have any readily available. (braided Cat5 would be awesome)
2 X LM317 Voltage Regulator - $1.50 at RadioShack
Various Resistors - A few buck$
Miscellaneous parts including, jbweld, paint, and heatsinks.
Jonesy9393 years ago
A future project I have in mind would be to build a Red/Amber LED Matrix display for the tail light and turn signals. Using an Arduino board to program in some quotes for other vehicles on the road. I.E. 'Back OFF!' 'Sorry' 'Thank You' 'Hi!' Really what ever I want, but I will keep it PG. In Texas you can get a citation for offensive gestures/language....
In the future, I would recommend using a 78L06, 6V regulator rather than the LM317. Since it's only designed to output one voltage level, it requires far fewer external components (a capacitor is about all you need) and can output up to 1A of current. Basically makes this project a lot easier and a little less expensive.
"Inventojack"

I'd love to build an L.E.D. tail light for our Father & Son build project.

We know "nothing" about "jack", and I was looking for help on this, saw this web site & how your help could make things work.

Would you be interested in helping us then ?

We have a rodio Shack ( "Source" up here in Canada eh ) in our small town.

This build, we are doing is a Bobber XS650, and our Son has fallen in love with a custom tail light & lic palte ubit. "No School" is the maker of it. It has two bulbs, but...... I kind think L.E.D.'s would be way cooler for guys pulling up behind our Son, in their cars :(

Anyhow . . . . just asking is all.
If this would be too much for "US", would it be possible to have some one make us one then ? :)

Thank You,
for your time on this matter, K ?

fraser

PS: I don't know how this web site page works, would I be getting an "E~Mial" notice should you reply then ? or do I have to get back on here to read your post ? :( :)


Why use a 6V regulator? Shouldn't you use a 12V regulator?
Unfortunately no. When using a voltage regulator, you really have to look at the minimum possible voltage that will be input into the circuit, compared to your target regulated voltage. A higher voltage input is usually okay within limits documented in the spec sheet for the device you're using. In this particular case the author notes that the minimum voltage the circuit will see during operation, which occurs when the engine is turned off, is about 10 volts. Due to the fact that regulators drop some amount of voltage (~2 to 3 volts depending on the particular device being used), we can only regulate the voltage level to an amount 10 volts (minimum input) minus that 2 or 3 volts, which brings us to around 7 or 8 volts to be used in the circuit. In step four the author had reached this conclusion, and decided to optimize the circuit for 6 volts operation. More voltage might be nice, but the author opted for a properly regulated voltage level instead (resulting in a more stable circuit overall). Hope that clears things up. If not, let me know, and I'll try to explain it a bit more clearly.
Thank you. It's been about 15 years did I did anything with electronics and my memory is a bit rusty. I didn't even think of the minimum input voltage.
No prob. Are you getting back into electronics then? I hope so. The basics are always the same. I bet it's like riding a bicycle. You'll begin to remember more and more, and have a good time.
jammin0 (author)  inventorjack5 years ago
Right on, I was just about to explain that but you probably did a better job than I could. I'm interested to know about the 78L06 chip you mentioned. Since I did this project I have sold the bike but I'm sure I'll do another, better led tail light build in the future as it was a lot of fun.
Actually, the 78** series is one of my favorite IC families, they come in 5v 6v 7v 8v 9v 10v 12v 15v 20v and 24v flavors, generally named 7805 7806 7807 7808 7809 7810 7812 7815 7820 and 7824 respectively. Different manufacturers use differing naming schemes, but those numbers will generally be in the manufacturer part number. I've found these regulators to be very reliable and they require an absolute minimum of external components (a couple caps). There's a pretty good FAQ about the 78** family here: http://www.rohm.com/products/lsi/power/78series/faq.html and the schematic at the following site will show just how simple they are to use: http://www.eidusa.com/Electronics_Voltage_Regulator.htm

The only real drawback to this type of regulator is that they are intended to output only one voltage level (though this can be tweaked a bit with some wizardry that's beyond the scope of this discussion. see the datasheet. Here's one for Fairchild's variation on the 78 family: http://www.datasheetcatalog.org/datasheets/228/390068_DS.pdf ). But if the majority of your work involves only one or two voltage levels (I use 5v and 12v most frequently), then they're a great investment, and very handy to have around.
jammin0 (author)  inventorjack5 years ago
The only other components I used were resistors, unless you mean heatsinks.
frollard5 years ago
That link to the circuit is down... To confirm, you're running 2 regulators in paralell, and one runs a high resistor after to run dim mode, then the other is 'past' the resistor allowing for the higher non-dropped voltage? COOL.
jammin0 (author)  frollard5 years ago
Yeah, that's about it. I just checked that site and it works for me. Check again, I'm to lazy to draw up the circuit but someone did it there.
looks good, and much brighter than the pics make it look when you watch the video. (i thought the pics looked a bit dull, but the video made it clear) i'm guessing the brightness drop when you apply the brake in the video is because the camera starts to automatically change it's aperture? also my two cents on the waterproofing: why not wrap it in gladwrap/clingfilm/whatever it's called in your neighbourhood in the interim, to prevent water getting to it, while you're ensuring everything is fine, then waterproof it thoroughly at a later date?
jammin0 (author)  TheScientist5 years ago
Yeah, you're right about the camera aperture. You can see especially on the closeup that it goes bright and then dulls away. The pictures are more dull because I'm running them off of about 4V battery power. It took some playing with and trying different resistor values on the voltage regulators to get the final brightness levels. That's a good idea about the cling wrap. I could wrap it and then tape around the edges with electrical tape or something. Luckily I'm a wuss and I don't ride very much in the elements but I do live in Oregon where it rains pretty much every day. :) Thanks for the feedback.