Well, now you'd never have throw away those used up cells, for this clock can run purely on the energy from 'used up' cells!

I had always wondered what to do with those used up cells I have been collecting, and after I came across this, I knew what to do with them. The only thing I needed to figure out was what could be the circuit behind the clock.

The idea to use popsicle sticks/tongue depressors and then staining to make them look like wooden pallets, came from this Instructable. Amazing idea!

This clock runs on at-least 4 (max. 12) used cells, all connected in series to provide the required juice.

This version of the clock really lives up its name, for it is almost completely made from recyclable material!

In case you like the idea, please do vote for it! I've entered it in the Hand Tools Contest and the Remix Contest.

Step 1: This Is All That's Needed:

1) Cardboard - Dual layered (Around 80Cm X 40Cm).
2) Wooden tongue depressors or Popsicle sticks (I used about 50 tongue depressors).
3) Some waste paper (for paper mache).
4) Clock Mechanism with Clock Hands (I salvaged it from an old clock).
5) PVA Glue.
6) Fast drying glue / superglue.
7) Wire (I used standard Breadboard wire).
8) Battery holders (I couldn't get single AA holders, and had to cut out the connections from double AA battery holders).
9) LM317 (Adjustable voltage regulator IC). (Here's the RadioShack link)
10) Diodes- IN4007 (six).
11) Resistors (one each) - 200ohm, 1000ohm.
12) Some coffee (around 4grams -- any type will do!).
13) Some used AA batteries. (At least 4).

HAND TOOLS NEEDED:

1) Soldering Iron with Solder (optional).
2) Scissors.
3) A Cutter Knife.
4) A Compass with Pencil for marking purposes.

Step 2: Cut the Cardboard!

This is pretty straight forward.(Remember, measure twice and cut once!)

Depending upon the length of the hands of the clock, you're using, cut two identical discs of cardboard of appropriate diameter (I took the diameter as 36 cm).

Now, with the help of a protractor, mark the twelve markings, at 30 degrees each, for the numbers.

Now, draw rectangles (as shown in pic-5,6) on each of these divisions and cut them out, and see if the cells/single AA battery holders fit in them (actually at this stage, the cells/holders should comfortably slide through this cell compartment.). Do this for both the discs.

In the centre of one of the discs, cut out another rectangle for the clock mechanism (depending upon the measurements of the mechanism you're using).
In the centre of the other, make a hole for the hands, as shown in the pic-7.

For the hanging part, I took two cardboard pieces (3cm X 3cm) stuck together with glue , and pierced them as shown in the pics- 8, 9 & 10.

Step 3: Clock's Face

Firstly, since the battery compartments could not be all straightly and neatly cut, I decided to cover the entire compartments in paper mache, to improve the appearance.

Now starts the fun part! Of covering the entire front face of the clock with wooden tongue depressors. I used these as these are wider than the Popsicle sticks, and therefore took less time and effort to cover the entire clock.

Although the clock looked pretty neat as it was, I decided to use wood stain on it to make it look awesome. of course, I was not going to buy a can of wood stain for the same!
So, I extensively tried vinegar-tea staining at first (staining a only sample wooden depressor each time!), but it didn't work in this case (it gave a grayish old look). I guess it has different effects on different types of wood surfaces.

Finally, I used several layers of coffee (around 4g coffee in 10ml water) to stain the entire face, and it really came out amazing (see the before and after pics). This is really a neat way of staining wood (at least the Popsicle sticks!).

Step 4: It's Circuit Time!

Firstly, In case you couldn't find single AA battery holders, start by cutting the positive and negative connectors out. Connect the positive ones with negative ones by wire (Pic-6). Now, just stick them in their place via super/fast drying glue.

The technical part is pretty simple. LM317 IC has the output of 1.25*(1+ r2/r1 ) {see Pic-3). Thus, with r=200ohm, r1=1kohm, the output should be exactly 1.5V.

Now, here's a catch: one could easily connect all the twelve batteries in series, and forget about using any sort of diodes or anything. But then this arrangement has two major disadvantages:
1) All the twelve cells are required at once. A single cell less, and the clock won't work!
2) Since the 'empty' cells, all won't have the same voltage and would most probably be dissimilar, it may lead to cells to leak (and believe me, it won't look good!).

One cannot altogether skip th second disadvantage, but I came up with this solution:
I decided to group the cells in a group of fours (three groups in total). This way, at a given time, the clock could work even with as few as four cells. In case all the 12 cells are connected, according to the schematic I've used, they shall all be in

The circuit is all connected as shown in the schematic (the detailed one). Please note that the ground shown in the schematic is actually used as the negative connection. In case you find errors in the circuit, do inform me about them. In case of any doubts, just comment below.

If you've done everything right, you should now have a beautiful, working 'Green' clock! :D

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In case of any doubts anywhere, feel free to comment below! :)