LED bike light : which driver?

Erasmus

Flashlight Enthusiast
Joined
Dec 29, 2004
Messages
1,077
Location
Belgium
Hi there!

I want to make a LED bike light with 1 LuxI as frontlight and 1 LuxI as backlight.

- dynamo is 3W/6V
- white LED in frontlight should be driven at 350 mA and has a typical voltage of 3.5V
- red LED in backlight should also be driven at 350 mA but has a (lower) typical voltage of 2.5V

Which driver is the best to use here?

Cheers,
Erasmus.
 

BentHeadTX

Flashlight Enthusiast
Joined
Sep 29, 2002
Messages
3,892
Location
A very strange dark place
Erasmus,
That would depend on the stability of the dynamo. If it reaches 6V and won't go higher with speed...and the dynamo limits at 500mA (3W) then you won't need a regulator. Wire them in series and use a resistor to set the current going through them.
If the dynamo varies and is not stable at the limits, things get much more complicated. I would use two downboy regulators with each LED driving off each regulator. Maybe throw a capacitor inline with the regulators to stabilize (stiffen) the power swings.
 
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