Ken_McE
Flashlight Enthusiast
- Joined
- Jun 16, 2003
- Messages
- 1,688
I needed some replacement bulbs for an emergency lighting system. Low power consumption LEDs seem like the superior choice for a battery operated equipment, so I decided to make a replacement unit.
I started by sawing out a round section from an aluminum heat sink about four inches across. Normally I think of aluminum as being a soft metal, easy to work. It turns out that when it's half an inch thick and you want a somewhat finished apperance, it's quite hard to work. I went with round so it would somewhat match the other head on the unit.
I mounted the heatsink on the bracket that originally held the 4 inch, 12 volt, 25 watt incandescent bulb. I liked that it can be swiveled through a large range of motion.
I Arctic Alumina epoxied nine one watt Luxeon stars to the face of the heatsink. Estimating by eye, I felt that the one large heatsink massed more than nine of the little Aavid Thermalloy heat sinks that are supposed to be appropriate for Luxeons. It may have less surface area though. I set them up in three strings of three, each with a ten or fifteen watt resistor.
I used the retaining ring from the original fixture to mount a piece of diffusing plastic from a flourescent light fixture in front of the LEDs so no one can hurt themselves by looking too closely at that many Luxeons.
I tried for beam shots but had trouble with them. The nine LED head puts out not so much a beam as a soft hemisphere of light. It will light up a medium size room enough that you can see colors and walk around.
I estimate that the new head costs roughly twice as much as the stock incan. bulb and uses roughly one third the power. If this means that the batteries only have to be replaced 1/3rd as often this represents a net savings. I don't believe the new head is as bright as the stock one though.
These images are hosted on something called imageshack.us, you can click on them for a closer view.
I started by sawing out a round section from an aluminum heat sink about four inches across. Normally I think of aluminum as being a soft metal, easy to work. It turns out that when it's half an inch thick and you want a somewhat finished apperance, it's quite hard to work. I went with round so it would somewhat match the other head on the unit.
I mounted the heatsink on the bracket that originally held the 4 inch, 12 volt, 25 watt incandescent bulb. I liked that it can be swiveled through a large range of motion.
I Arctic Alumina epoxied nine one watt Luxeon stars to the face of the heatsink. Estimating by eye, I felt that the one large heatsink massed more than nine of the little Aavid Thermalloy heat sinks that are supposed to be appropriate for Luxeons. It may have less surface area though. I set them up in three strings of three, each with a ten or fifteen watt resistor.
I used the retaining ring from the original fixture to mount a piece of diffusing plastic from a flourescent light fixture in front of the LEDs so no one can hurt themselves by looking too closely at that many Luxeons.
I tried for beam shots but had trouble with them. The nine LED head puts out not so much a beam as a soft hemisphere of light. It will light up a medium size room enough that you can see colors and walk around.
I estimate that the new head costs roughly twice as much as the stock incan. bulb and uses roughly one third the power. If this means that the batteries only have to be replaced 1/3rd as often this represents a net savings. I don't believe the new head is as bright as the stock one though.
These images are hosted on something called imageshack.us, you can click on them for a closer view.
