Gamasonic Solar Flashlight Toggle Switch Mod
Charles Shapiro
17 Dec 2025

This is a modification of the Gamasonic solar-powered keychain
flashlight which replaces the original case and pushbutton switch with
a new case and a toggle switch. This makes it much more useful for
camping or power failures. After approximately a 2-hour charge in
full sun, the light should provide about 4 hours of reading-level
light. I turned one of these on at about 8 pm, and it was still
glowing enough to show distinct spots on my hand at 7:30 the next morning.

A crate of over 500 of these flashlights turned up at my local
makerspace. None of them would light, but we soon found that the only
defect was the pushbutton. The solar cells, batteries, and LEDs all
worked fine.

Materials:

3D printed box and lid (STL s included ) I printed mine in Natural PLA
with a 0.6mm nozzle on a Prusa MK4S.

Subminiature panel mount SPDT toggle switch with 6 mm (1/4")
shaft. Adafruit sells this one ( https://www.adafruit.com/product/3221
)

Two pieces of 0.34 mm (22 gauge) hookup wire, about 7 cm long

Rosin core electronic solder and soldering iron

Steps:

1. Dissect the flashlight out of its plastic case. Four screws hold
   the case together. They are tiny phillips head screws. A J000 (1.5
   mm) bit or screwdriver will fit them. Go gently or you risk
   stripping the heads. After you remove the screws, the case will divide
   in half and you can remove the flashlight in one piece. Save the screws!

2. Remove the pushbutton switch from the circuit board. The easiest
   way to do this is to lay the hot end of your soldering iron across the
   two legs of the switch along the long axis of the flashlight and grasp
   the switch with a pair of tweezers. Pry those two legs loose from
   their pads, then heat the opposite side in the same way to remove the button.

3. Solder in the switch. Strip about 2 mm of insulation from one end
   of your wires, and about 4 mm from the other end. Tin both ends. The
   pushutton shorts between the pads on the long axis of the flashlight,
   so you will need to solder one wire to a pad farthest from the LED
   lights, and another wire to a pad nearest to the LED lights. Be
   careful not to solder bridge the pads, or you'll have a light that
   won't turn off. Bend the other ends of the wires into hooks and
   solder them to the switch, one to the center tab and one to either
   one of the edge tabs.
   If you've done this right, the light should turn on when you flick
   the switch one way, and off when you flick it the other way. If it
   doesn't turn on, try charging it under an incandescent light for
   around 20 minutes before deciding you have made a mistake.

4. Assemble the light inside the case. Push the switch through the
   hole in the back and secure it with the switch nut. Carefully slide
   the solar cell and LED assembly into the case with the solar cell
   facing up; the two wings just fit into the wings of the case. Double
   check that everything still lights up and turns off.

5. Attach the lid. I put a piece of plastic wrap over the open side
   of the case to add a little waterproofing; your mileage may vary.Place
   the lid on top of the open end of the case, then screw it down at the
   corners with the screws you saved from the original flashlight.

Congratulations, you're done. For Extra Credit, you can remove the
keychain from the original case and attach it to the back with a key
ring or a bit of wire to provide a handy way to hang the light up