Solar Powered Clock

Convert a standard clock into one that is recharged by solar.   A fairly easy build with optional soldering and low costs make this a good kid friendly project.   My son and I built this one afternoon and he was impressed with the idea of easily reusing modular parts of one device to build another.


Needed:
Friendly looking kid to model things
Clock that runs on a single AA battery
Solar powered garden light, the cheap kind with a tiny solar cell and a little LED
Basic tools (screwdriver, cutters)
Soldering iron and heat shrink are optional.  (but if not available, some tape, preferably electrical tape, is needed)

Step 1 Breaking Down the Solar Garden Lamp

First things first is getting all the parts out of the doner garden lamp.  The necessary pieces are the solar cell, the AA rechargeable battery and the battery contacts. 

Using a screwdriver or other necessary tools open the case and take a look around.

The AA rechargeable battery is an easy thing to remove.  Do that first and set it aside.

Before cutting anything, check which lead of the solar cell is positive (+) and which is negative (-). Sometimes it will be marked on the cell itself, in which case you can jump to the next paragraph below.  Unfortunately sometimes it is not marked. If not, and you have a mutlimeter, jump to the next paragraph.  If no meter is handy, you'll need to take a close look at the circuit starting from the positive lead of the battery.  Trace it back through the circuit board and to one of the wires of the solar cell.  Mark this wire as positive.

The solar cell will be attached to a circuit board with a couple of wires.  Simply cut these wires near the circuit board to keep the lengths of wire as long as possible.  Then pry, cut or unscrew the solar cell from the plastic cover (different designs use everything from glue to screws to press-fits, just be careful not to put too much force on the cell itself as it is fragile, especially in the very cheap lamps).

The battery contacts will hopefully come easily out of the case as well, and if necessary clip the wires from it that lead to the circuit board.  It may require some cutting of plastic to get the contacts intact.

There are some other good parts in here for other projects:  switch, photocell and LED are all available for use.  The rest is pretty much junk though, don't let it clutter up your workshop.