First Try

I ordered a couple SSC p7 bulbs, and they just came in. I have read a little since I ordered them, and placed another order for a driver, batteries, reflector...... Since I have the bulbs sitting here, I decided to try and use one of them.

I tried a few different reflectors, and finally decided on a AA maglite. I drilled out the reflector hole to 10mm, and the led fits it perfectly. The problem was the aluminum housing. My bulbs came attached to a metal plate, and it didn't fit into the housing. I was afraid the grind so close to the bulb and all the contacts, so I put the housing on the lathe, and opened it up. The plate fit perfectly.



Everything actually fits pretty good. The plate on the bulb sits aluminum to aluminum with the body of the flashlight, so I believe the whole body will work as a heat sink. My goal is a small, bright, helmet light for night mountain bike riding. I want to mount a socket in the back end. I think I can have a power pack in my back pack, with a cord running to the helmet light. I think the plug will be good if it gets caught on some brush. I'm hoping it will yank the plug out instead of pulling off my helmet.


So, do I have a problem in the works? Should I epoxy the bulb to the flashlight body, or is the cap holding it tight to the body enough? Any other ideas for improvements? This is my first try at building a flashlight, and so far I'm pretty happy. We'll see what happens after my first ride. :thumbsup:

I'm just about there. I tried to put a plug in the side, but it wouldn't fit with the curvature of the body. I ended up just running the wires through the hole. None of the switches I got will work either. The good thing is that I can power the thing up, and wow. I have been riding with a Surefire 6P led, and this tiny thing blows away my Surefire. I'm amazed, shocked, and happy. Unfortunately its raining pretty hard here tonight, so no test ride.

I do have a question. Can I cut down the body, and re-thread it so the tail cap will go back on? With the separate battery pack, the light weighs next to nothing. I can't even feel it on my helmet. I think it would look even better if it was a couple inches shorter though.

First off the P7 isn't a bulb it is a Light Emitting Diode (LED), sorry but you have to get that right. The second thing is that you couldn't wait till the driver came so your running the P7 without current limiting or at least it sounds like you did. If we connect a battery across the LED without some current limiting then the LED would probably attempt to take as much current as it could and then would be destroyed maybe getting a little blue in color just before it dies. And then you would have to wait weeks again for a new one. You need some current protection, the simplest is a resistor, however this works, but as the battery drains so does your brightness. If you want to play get a resistor for now!!!! figure the size by knowing the P7 Forward voltage , desired current, power source voltage. Lets say the Vf of P7 is 3.4v and the desired current is 2.5A and your power source is 6v.

Ohms law V=IR so we have 6v but only need 3.4v of that so the rest has to be disappated in the resistor or 2.6v across the resistor. So if we solve for R in Ohm's law we get R=V/I R= 2.6v/2.5A or ~1 ohm so you need a 1 ohm resistor for this scenario. And the power of the resistor is important P=VI 2.6(2.5)=6.5watts.
Remember that three 3ohm 2.2watt resistors in parallel would work as a 1 ohm 6.6watt. Any larger resistor would work, you'll just be less bright.

You can reduce the size of those metal plates the P7 is attached to to just about the legs of the P7. You just solder to the leg but do it quickly and make sure the LED doesn't rise up from the metal plate. That plate provides the first heatsinking to the LED. More heatsinking never hurts, since you have the lathe you should make one that drops in the front of the maglite. Do a google on here to see heatsink shapes.