Bike light with dimming, recommend a driver?

[Steelwolf]

Sort of as an adjunct to my other recent thread in this forum...

I'm planning to make an "All-in one" bike light, i.e. unlike the Lupine Wilma or PrincetonTec Switchback, where the light and battery are separate, I would like a single unit for easy removal.

Taking a cue from the abovementioned lights, I'm think of 3 or 4 Crees. Perhaps even going the whole hog with 7 or 8 Crees. I'm not overly concerned about maintaining constant light output as I'm sure good NiMH or Li-ion cells would maintain fairly even voltage over a standard run. However, considering the number of emitters in close proximity, and the power going in, some sort of driver/current controlling circuit would be prudent to avoid thermal runaway.

I would also like to have dimming available.

So I'm thinking about the bFlex, the Fatman and the upcoming MaxFlex as the possible drivers. I'm also toying with the idea of using the AMC7135 from DealExtreme, or a DownBoy or SOB, coupled with a PWM switch, such as Elektrolumens' PWM IQ switch, or TaskLED's D2DIM.

Or, from a boost side, would the PWM IQ or D2DIM work with a Sandwich Shoppe board (like the NexGen or GD or Shark)? How about with a LEDSupply MicroPuck or BuckPuck?

Any suggestions or advice?

 

[Steelwolf]

Why has this been moved? I understand that it is related to bike lights, but I'm trying to get an idea of a suitable electronics driver to use with the system. Isn't this a question more suited to the flashlight electronics forum?

Anyway, wherever this thread ends up, the main questions are:
1. Apart from the stuff from TaskLED, are there any other drivers with dimming function, preferably stepped dimming rather than trimpot, though I'm sure I can work with a multi-turn switch with various resistors.

2. If I were to use one of the buck converter boards like SOB or Downboy or even BuckPuck, could I put Elektrolumen's PWM IQ switch, or the D2Dim from TaskLED on the input side of the board to control dimming? Or should it be on the output side of the board?

3. If I were to use a boost converter like the MicroPuck, NexGen or Shark, could I put the PWM switch on the input side of the board to control dimming?

4. Should I forget about using a driver at all, since I'm planning on using either NiMH or Li-ion, and just match the voltages as close as possible, then put in a current limiting resistor and a PWM switch?

 

[rufusbduck]

Why has this been moved? I understand that it is related to bike lights, but I'm trying to get an idea of a suitable electronics driver to use with the system. Isn't this a question more suited to the flashlight electronics forum?

Anyway, wherever this thread ends up, the main questions are:
1. Apart from the stuff from TaskLED, are there any other drivers with dimming function, preferably stepped dimming rather than trimpot, though I'm sure I can work with a multi-turn switch with various resistors.

2. If I were to use one of the buck converter boards like SOB or Downboy or even BuckPuck, could I put Elektrolumen's PWM IQ switch, or the D2Dim from TaskLED on the input side of the board to control dimming? Or should it be on the output side of the board?

3. If I were to use a boost converter like the MicroPuck, NexGen or Shark, could I put the PWM switch on the input side of the board to control dimming?

4. Should I forget about using a driver at all, since I'm planning on using either NiMH or Li-ion, and just match the voltages as close as possible, then put in a current limiting resistor and a PWM switch?

What sets Georges drivers apart is their capacity. They can drive more leds than other drivers are capable of using one controller. If you only want one light then it better be bright so you might want to opt for a 5 or 7-up light and a maxflex or hipflex(maxflex is boost, hipflex is buck regulator). I run a quad xpg w/ maxflex on my helmet and another quad on the handlebars. If this light is for road use only you can get away with less light and run 3 leds in parallel and slave the outputs of three 7135 driver boards together. Nimh has the advantage of flatter discharge curve from ~ 1.4v to 1v, lithium is lighter but it's harder to 'match' voltages since the discharge cureve goes from 4.2v to 2.5v. If you want to drool over a picture, check out cutters 7-up light or trouties similar unit but both will set you back a few beans.
Pwm dimming is a bit less efficient than switching regulators and a multiposition switch with resistors can replace a pot too.