DIY : R1100S LED tail light

[Buzzz]

I gave up on proposing gear indicator packages for the US.
I know that you have enough potent guys on your side of the lake to build it and sell it.
I prefer to share my ideas with you.

So, after the gear indicator, I wanted to do something else.
Since the purchase of the bike, I had always wanted a LED tail light.
But again, I didn't want to pay £40 for that.
My objective : less than £10.

So I have started to think about it.
I have struggled a bit to determine how to place the LED, how many, how bright they should be. It's not that easy to make a nice pattern with the shape of the original tail light.
Here is what I wanted for the sidelight :


The stoplight :


How the LEDs would be put on the circuit board :


And then the time has comme to build it.
In the end, I have decided to go without an electronic circuit board. Otherwise, price would have been the double.
Here is what I have used :
- 50 x 14000mCd red LEDs from the bay
- 10 x 100Ohms resistors from a local dealer
- 3 x 560Ohms resistors
- 2 sq.in of testing electronic board
- 15 sq.in of aluminum sheet

Total had a cost of about £5.
This low price is mainly due to the LEDS from the bay. But it had a major drawback. I had to test the full working range of the LEDs to determine the correct resistor values I needed. There was no information given about the LEDs except their brightness...
So I have patiently made recursive tests with different resistor values and measured the intensity and voltage to build the curves.

Then, I have decided of an electrical layout :

As you can see, each row of 5 LEDs has a 100ohm resistor. Only the 3 rows dedicated to the sidelight have an addition 560ohm resistor to look dimmer.

[Buzzz]

The mechanical part.
The first step has been to cut the aluminum sheet to specs and trace the position of the LEDs on its back side to regroup them like on the electric diagram.
Then, I have drilled all the LED positions with a 4mm bit instead of a 5mm (the LEDs have a 5m diameter).


Then, I have lightly punched each hole with an awl to have a tight fit for each LED, so they don't need glue or anything else to stick to te aluminum support.


With all the LEDs in place :


Dummy assembly :


Next step was the net of resistors :


A small test on the workbench before I put everything in place :


Tests on the bike :


If you're interested in this modification, here is the general layout of the LEDs :

If you print it at 150dpi, it should be at scale.

[Supersteve]

Looks very nice, would you ever consider integrating the turn signals into a similar design with a clear/ tinted lens?

[throttlemeister]

I'd like to see pics of it working in direct sunlight. In my experience, LED's need to be almost blindingly bright at night to be visible and useable during the day.

My idea would be to use super bright LED's that stand out under direct sunlight, and add a foto diode that dims it somewhat when there is little ambient light like at night.

[Buzzz]

You're right. It's hard to have a good result both during day and night time with LEDs. In my case, I find the result totally acceptable in both cases (compared to standard light bulb). I guess this issue is the same with the aftermarket products.
Sure, I will try to post pics in sun light.

[Buzzz]

Didn't have the chance to take a day picture yesterday.
However, Last night I have mounted new LED turn signal that I bought.
As you can see on the pic below, the sidelight is nearly as bright as the turn signals.

[flatbutt]

excellent!

[AZ-Twin]

You do nice work Buzzz!

[Lesley Ilic]

Re: LED display control 32 LED's of two pins
Reply #4 - 22.12.2008 at 01:52:49 I've been working on a project that requires controlling 32 LEDs, (A binary clock/calendar). So I checked out the shift out tutorial on arduino.cc LED Bulbs Wholesale
blue led strip
led tube lights
I could not easily locate a 74HC595, but a bit of reserch shows that Jaycar has the Texas Instuments 74HC164 http://www.jaycar.com.au/products_uploaded/ZC4857.pdf avaiable instead.
A bit of poking round and checking the Datasheet, and messing with the shiftout tutorial, I've finally got it working

These chips do not appear to need a latch signal, I've used the shiftout tutorial code, with the latching deleted. It appears that by having the Clear pin permanently on HIGH, the clock signal is all that is required.

Attach the Clock signal to Pin 8, Data signal to pin 2, attach Pin 9 (VCC) and 14 (CLR) to +5V, do not connect the latch, and the single chip Shiftout code will function. (you can delete the Latchpin lines in the code)

Other chips in series are connected the same way, except for the data line, which is daisy chained from pin 13 to pin 2 (Yes, both the LED and the Serial in Pin are connected to Pin 13), and again the shiftout two chip code will work (again you can delete the latching lines). I've currently got 4 of these chips working in Series, giving me my 32 LEDs to play with.

You can perhaps set up one serial array for each channel, and drive 30+ 3 channel LEDs from only 6 pins on the Arduino.