This is my first instructable and is a lot inspired by this instructable of awall99:
My result is quite similar, but I used a smaller sized pocket watch and thus had a different approach.
- LED watch
- Pocket watch
- Wire (without isolation or coating)
- Electrical tape (for temporarily mounting)
- Heat-shrink tubing (or electrical tape,...)
- Pen spring
Step 1: Disassemble the Watches
First you have to used a knife (or more suitable tool) to open the lids of the watches.
You just have to pull out the watch and then push the glass from inside out. To prevent any damage use paper towels.
It is needed to cut the connection rod. I used a wire cutter. The button that is used to open the cover should be loose now. Remove all the connection rod from the button, except the moving part, because it is still needed. Then you can glue the button back to its place. Be careful that the button is still pressable.
Push the glass out of the pocket watch as with the LED watch.
Step 2: Switch Glass
Put the glass of the LED watch at the position of the glass of the pocket watch. Notice, do not put it from inside out. Put it on the front of the watch, a small edge will be visible. Fix it with some electrical tape and the glue it from the inside to the watch. The glue won't be visible, because the glass has a black border. Just don't take too much glue and be careful of not dropping some glue on the visible area.
Step 3: Electronic
First bend the wire as shown in the picture, solder it to another isolated wire, and cover the connection and the pure wire with a heat-shrink tubing. Leave the end free.
The other end is soldered to the LED watch's button connection. Glue the wire into the pocket watch, so that the free end of the wire has a connection to the pocket watch's button, when it is pressed.
Also position the LED watch on the glass and glue it carefully to it.
Finally put a pen spring to the battery holding. This is needed to make the whole case of the watch to the "ground" of the circuit. Close the lid and everything should work.
By the way: Before you close the lid, you have to set the correct time. If you want, you can drill a hole at the position of the second button of the watch inside, I leave it out for a better look.
P.S. I tried to solder a wire to the ground of the LED watch and the case of the pocket watch, but it is quite hard to make the connection to the case strong enough, so the pen spring was good alternative.