Bike Lighting


For the bike I have been working on a set of diode lighting. This is basically because I taught that commercial option was too expensive and it was also a good exercise in electronics as we were experimenting with some switching electronics at work for another application and so it “happened” that parts got ordered that actually fit perfectly for driving a couple of high power LED.

Said and done, after experimenting with some various LED;s (first picture) that basically where no good, I ordered a couple of 5W Luxeon.

The LED;s are so called “star” LED, that means that they come on a small circuit-board shaped like a star. The circuit board has one side made in aluminium for cooling and fits with plastic lenses that can be ordered and just clicked on to the circuit board.

For the housing I made a waterproof aluminium house that should take care of the heat and not short circuit when used in rain. The result is the light at the top pictures of this page and at current state is the only physical result of the project.

To be able to use the light, you have to dissipate the heat generated so the housing should be made in some heat conducting material, as aluminium. However the heat is generated and dissipated at the back of the LED, hence the front of the light can be made in plastic to save weight.

I made a new design that was a bit more compact and rugged, this is shown in the middle right picture.

As I wanted the housing to be even lighter I developed the design and incorporated cooling channels that when the air flows against the lamp will flow into the aluminium and cool the back even better. In all the lamp is less than 100 grams. The lower two pic at right shows this design.

Together with this I have made the controlling electronics with a circuit from Maxim that gives an efficiency of about 95% (not fully tested yet, but early indications point to this). This is also a very compact circuit (and cheap) that needs no cooling so I will be able to cast it in epoxy in the cap of the battery pack. Cool.

I will post pictures of all this as the project evolves. Right now I am focusing on the scope to be done.