So I was looking for some AA hosts to make an IR light and the FastTech Pocket 3W LED light seemed like a good price and place to start. From the review comments, it looked like people got this for a paltry cent but I wasn’t so lucky. For the price, it seemed OK. Not great but for what you pay for, it will do. It’s aluminum, cheap anodising, no o-rings but sturdy enough.
Here’s a picture.
So from left to right, plastic lens, plastic reflector, LED board and plastic driver pill, the spring that was holding the pill in, body tube, tail cap.
Basically there is a ridge inside the head of the body tube. The spring sits on that ridge, the pill goes in next followed by the reflector, there is a groove just below the crown where the plastic lens snaps in holding everything in place. The spring makes contact with the ridge which has no anodising and a leg of the LED bent under and up the side of the pill. It is the bridge that holds everything in place. It was hard to get the pill out, I mullered spring in getting it out. I couldn’t seem to be able to push the pill through the lens and pushing from the lens didn’t budge. I ended up hooking out the spring from the tail thus stretching it out but that gave the head just enough room to slide down and from there I could press on one edge of the lens to pop it out of the groove.
The pill itself is quite simple and plastic. The LED beam is rather purple and the ringy. Not sure what the LED is. There looks like a single SMD IC, CX2601 is what I could make out, plus a 100uH inductor as well. The IC seems to be similar to the Zetex 380 in that it will not light up the LED if the input is below 0.8V and uses the inductor to control current to the LED. The Zetex seems to have smaller current draw from the battery. I hate soldering (or desoldering) surface mounts so that’s all the measuring I can do.
As a host body, it is a good price and there isn’t that much work required to improve it but it is more than I was wanting. The lens that holds the pill in place is probably the most annoying thing about it but it can be overcome. Was after a LED and driver swap and I think the pill, lens and spring needs rethinking in this thing but this is still a reasonably good cheap option for an AA host.
Edit: Some measurements:
Inner diameter of the head, 17.81mm
Depth from lens groove to ridge, 32mm.
Depth from lens groove with AA battery inserted and spring fully compressed 22.32mm
So a 17mm diameter pill would do the trick but need to fit reflector, pill and lens into about 20mm I’d say.
For anyone who cares about using this light as a light, tailcap draw on the original driver seems to be around 70mA to 100mA. The fresher the battery, the closer to 100mA.
