A guide to making your own LED tail lights.(No Lexarse lights in here)

[Zip]

Im not sure how it would look but it could be a nice way to make the MK1 look a bit more modern.

I dont want to see this guide being abused and seeing Lexarse lights come from it lol

I found this on my daily bordem web trawl. Ill post it all up incase the website disapears.
Its to do with wiring them up for a Motor Bike but im sure it could be used to wireing them up for an Mk1:thumbsup:



Building an LED tail light

Damn but I love LED?s ? they make coloured light instead of white so it doesn?t need filtering, they run cool, draw less power, are directional, waterproof and vibration-proof, and basically never die if you treat them nice. All of that means that in a place that vibrates, gets wet & dusty, and is important for visibility on a dark night LED?s are the perfect answer. The down-side is that they put out a very tiny light so you can?t use just one or two; you need a bank of them. Of course that means that if one or two of them DO blow you?re still visible, and since the lifespan on these things is so long you could theoretically run your bike twenty-four hours a day for eleven years before one of them dies on its own!

Design Considerations

If you don?t have a clue about LED?s you might want to read this bit; if you already know all about them feel free to skip to the circuit diagram.

You can?t just plonk a few LED?s into the bike?s wiring as a direct replacement for a light bulb however; they have a few differences. For a start they only connect one way, and simply won?t work backwards. ?LED? is short for Light Emitting Diode, and a diode is basically a valve for electricity, it?ll let it flow in one direction but not the other. More importantly if you connect an LED directly to a power source, it?ll immediately draw infinite current, make a ?pfft? noise, and then go eternally dark. To get around this we use another component called a resister to limit the amount of current the LED?s can draw.

We also need a regular voltage source so there?s another small bit called a regulator that sees to that. Yes I know your bike has a 12 volt battery, but when it?s running it can actually get up to about 14.4V. Since we want to set the resistors up to deliver the max safe current to the LED?s for maximum light we have to know what the maximum voltage will be. We could set it up for 14.5V, but then when the bike?s idling the light will be dimmer than it needs to be. The better solution is to use another small component called a regulator; these devices will supply a constant 12 volts, as long as the bike?s supplying at least that much.

Another thing to consider is how we?ll be putting all these bits together. There?s basically two ways to wire up a bunch of LED?s; serial (where one resistor supplies power to several LED?s) or parallel (where each LED has its own resistor). Serial?s nice and easy and requires less resistors taking up real estate that could otherwise be used for LED?s, but requires more voltage and if one of them blows the whole lot in that serial chain go out (the same as Christmas tree lights). Parallel uses up more real estate and draws more current. The solution is to use a mixture of the two; to make several small serial chains, and put those chains in parallel.

Finally we need our light to perform three functions ? it must illuminate the licence plate in white light, it must glow brightly for the brake light, and glow less brightly for the tail light. The standard bulb does the first function by producing white light in all directions and having a clear section at the top of the lens. The second function is done by effectively having two bulbs in one, with the second (brake) brighter than the first (tail). The issues we run into here are that LED?s are directional and make coloured light which requires separate white LED?s aimed upwards at the licence plate. To get the ?two stage? lighting for tail/brake we could either put double the amount of LED?s required in, with half of them dimmer than the others, but since space is limited I chose to have the LED?s do ?double duty? with a dim mode and a bright mode. There?s a small adjustment so you can set how dim you want your tail-light, and the brake-light is at full brightness.

One thing to be aware of is that the taillight housing?s interior is chromed plastic, which is conductive. A simple way around this is to make an insulating ?plate? to sit between the veroboard and the reflector; I cut mine out of an icecream bucket lid. J

The Circuit Diagram

As you can see from the diagram it?s a fairly simple circuit. If you had space you could add several more serial chains of LED?s to the brake/tail light before the overall current became an issue

http://www.twobeds.com/upload/userfiles/Zip/LED%20diagram.jpg
The circuit relies on the fact that the output from the taillight regulator passes through the trimpot, which means that when the brakelight?s regulator enabled it?ll simply override the taillight one. The licence plate LED?s need to be illuminated whenever the taillight?s active but must always be at full power so they draw their supply before the trimpot. These LED?s are wired in parallel due to their higher voltage drop, which would require a 16V supply if they were wired in series. Brightness of the taillight is controlled by the trimpot, however this could safely be replaced with a 68 ohm resistor for simplicity and space saving.

[Zip]

Building It

If you want to make changes to my design feel free, but you’ll have to work out how it changes the math yourself. I originally used twenty-four “jumbo” 10mm super-bright red LED’s for the taillight and five 5mm super-bright white LED’s for the licence plate light. It turned out that the bottom left & right red ones fouled the lens so I later replaced those two with 5mm ones with the same electrical properties. You’ll need several resistors of two different values, two voltage regulators, and a trimpot (miniature variable resistor) to set the brightness of the tail-light compared to the brake light. There’s a pair of diodes in it too, to stop power from one light feeding back into the other light’s circuit on the bike. You’ll also need a board to mount it all on. Since this is a fairly simple circuit I used “vero board”; this is a fibreglass board with small holes drilled at regular standard spaces and strips of copper on the back joining the holes in lines. It’s an easy matter cut the tracks with a sharp knife to make separate “sub-tracks”.

Here’s the list of parts I used. I’ve provided the “forward current” (If) and “voltage drop” (Vf) of the LED’s I used – if yours are different you may need to alter the resistor values to suit. Brightness of the LED’s is measured in millicandella (mcd). Supplied part numbers are from my local supplier “Jaycar Electronics”. You can check out the parts on their website (www.jaycar.com.au) for more info.

Parts List
Please note that because this guide was Origonally written out for Bikes you will need to use more LEDs, a different design and a few different parts

* 22 x 10mm Red 10000mcd LED, If = 50mA, Vf = 2.3V, #ZD0202
* 2 x 5mm Red 10000mcd LED, If = 50mA, Vf = 2.3V, #ZD0156
* 5 x 5mm White 7000mcd LED, If 30mA, Vf 3.5V, #ZD0192
* 2 x 1N4004 diode, #ZR1004
* 2 x 7812 or LM340T12 12V 1A Voltage regulator, #ZV1512
* 1 x 250 Ohm vertical trimpot, #RT4006 (replace with 68 Ohm resistor for non-adjustable taillight)
* 5 x 300 Ohm ?W resistor, #RR0559
* 6 x 56 Ohm ?W resistor #RR0542
* A roll of tinned copper wire, to use for links.
* Veroboard, solder & iron, 3 x male & 3 x female insulated spade connectors.
* 3 x short lengths of 12V hookup wire (preferably black, blue and red)

The first step is to cut the board out and create the four necessary holes to fit it over the posts in the housing. Here’s the scan I took of the board ready to be populated… probably a good idea to save it, print it, and use it as a template.

http://www.twobeds.com/upload/userfiles/Zip/Board.jpg
Vero board, cut out and ready to populate

Once your board’s cut out and fits inside the lens check that none of the copper tracks touch the sides of the posts to avoid them shorting on the chrome. Next step is to cut the tracks at the appropriate spots. I use a fine tip on a dremmel but you can use a sharp knife just as easily. It’s a good idea to use a multimeter, test light etc to ensure that the tracks are properly cut before you populate the board.

Here’s a board layout with the approximate positions of all the components, as well as the track cuts. Remember that this is viewed from the component side, so reverse it when you turn the board over to make cuts. (Red and Black rectangles on the left show + and – tracks for reference.)


http://www.twobeds.com/upload/userfiles/Zip/Board%20Diagram.jpg
Component layout

Once you’ve cut all your tracks, put your wire links in, then the resistors, diodes, trimpot and regulators. Finish with the LED’s as they’ll cover some of the board’s real estate that you need to get to for the links. Care should be taken to ensure that all LED’s are inserted to the same depth for appearance. The licence plate LED’s should be inserted with approximately 15mm of their leads above the board, and the taillight LED’s should have about 5mm. Bend the licence plate LED’s up at a ninety degree angle and point the outer two of these towards the respective edges of the board slightly. The solder the three wires in place, using the blue for brakes, red for taillight, and black for negative. Once the components are in place test the board using a 12 battery or power supply. If you’re using your bike’s battery it’s best to disconnect it from the bike first, just in case. With the GND lead connected to the negative terminal of the battery and the Tail lead on the positive the licence plate LED’s should be on at full power with the red LED’s on dimmer. Connect the Brake lead (leaving the other two connected as they are) and the red LED’s should turn onto full power. Adjust the trimpot (if used) for a suitably dimmer taillight. Once you're satisfied that it's complete and ready to fit it's a good idea to use a little hot glue, silicon, or anything similar to fix the LED's in place so the vibrations don't break the solder joints.


http://www.twobeds.com/upload/userfiles/Zip/Finished.jpg
Finished and fitted with out the Light cover

Fitting it to the beast

Remove the bulb socket from the taillight assembly and cut the three wires leading to it close to the socket. Remove the two rubber grommets from the socket’s mounting holes, and place them in the equivalent holes in the LED board. Connect female spade connectors to each wire. Connect male ones to the wires leading from the LED board, place your insulating sheet (carefully cut out of the high-tech ice cream bucket lid, remember?) in place over the four posts, then press the LED board into place over the posts. Turn on your ignition (and light switch if fitted to your bike) and check that the LED’s behave as before, as both tail & brake lights, as well as licence plate. Replace the lens ensuring that it’s seating firmly on its seal. Enjoy.



http://www.twobeds.com/upload/userfiles/Zip/Finished%20lights%202.jpghttp://www.twobeds.com/upload/userfiles/Zip/Finished%20lights.jpg

Taillight on the left, brake light on the right

http://members.optusnet.com.au/~matt_l/taillight.htm

Just remember, Say no to Lexus lights

[Goldy]

Nice guide! :clap: Circuit looks pretty straightforward as well.... who's goin to give this a go on the mk1 then :shades:

[superchargedsam]

Zip top find fella ! that looks brilliant and am sure I have seen somethign similar before but its awesome to have it where it belongs, within the folds of TB !

[JMR_AW11]

Looks good but I think the datasheet advises to fit decoupling capacitors on the 7812 regulator inputs to ensure stability.

How hot does the trimpot get? it may run quite warm at certain settings.

For a car tail light in the spoiler you could control the LEDS with a simple PIC micro to get some special pattern effects (this may be illegal BTW ???)

[superchargedsam]

JMR rekon you should spend more time over here fella ! What part of cheltenham you in fella as often over that way in my supercharger and often stay in morton in marsh !
We like nice electronic things on this site ! more buttons the better I say !

[Zip]

I found a website that you lot could use to by LEDs if you do this :)

http://www.ultraleds.co.uk/