We use the laser pointer quite a lot. We also have our fair share of electrical problems. We wanted to have our laser pointers powered by plugging them into the wall, instead of 2 AAA’s. My original design was to put a barrel plug, into the lasers. However after I began construction, and had some trouble find the exact power plug I would need, I came up with a new solution. It was decided to put USB plugs on the end of laser pointer. USB can provide 5v at 500mA. Our laser pointer uses 3v with less than 100ma.
BOM : Laser Pointer, USB Cable, LM317, 680 ohm resister, 1k ohm resister, Wire.
The first thing to do, is to drill a small whole through the side of laser. This is so we can attach the power wire to the laser. Then cut the USB cable so that we can get to the wires. Cut two 1 inch pieces of wire, and strip the ends. One will be soldering to the spring in the Laser. The second will go through the hole we drilled earlier, and soldered in place. Solder the 680 ohm resister between Vout and ADJ on the 317. Solder the Vout to the wire that is connected to through the hole in the laser pointer. Then you will need to solder the 1k resister to the ADJ pin. The other side of the 1k resister connects to both the Ground from the USB cable, which is usually the black wire and the wire from the spring. The the last leg of the 317 is soldered to the red wire from the USB cable, which should be 5v. The we completely covered the components, we just soldered, with hot glue.
You can see the wire bent into a hook shape. One you hook the wire around the spring, solder it in place.
This is what it will look like when all the connections are soldered.