3 Watt LED Bike Light
February, 2008, Rev c
Prototype 5 - Single Cree and regulator
This light is the same as prototype 4, except I did not have a supply of transistor heat sinks and don't expect others to have any either. So for a substitute I used 3/4” aluminum angle stock for the side fins, which available at local hardware stores. All four pieces of the heat sink were bonded using JB Weld, and clamped tightly until hardened. So this prototype has 3/8” of heat sink thickness behind the LED which gives it good thermal mass. In this case I made two of the prototypes.
I also used the cheaper P4 bin LED saving about $5 over the prototype 4. (Although prices fall fast as LEDs evolve.) The LED was bonded to the heat sink using the Arctic Silver epoxy. GE Silicone Adhesive was used to bond the optic lens to the heat sink.
The resulting unit is a little smaller than the previous and still bright enough. For comparison a light meter was used for relative brightness. The Q5 prototype 4 read 17,000 lux, only 18% greater than this P4 prototype at 14,000 lux, both drawing about 950 ma. In prototype 3 each LED read 11,000 lux at 550 ma.