This will show you how to add a timer... plus add a much larger battery supply. The voltage of 4.5v is the same, but the D Cell batteries will run a whole lot longer!
Wikipedia tells us that a AA battery has 1/5th of the life power (Amperage) in relation to a much stronger (and larger) D Cell. A D Cell will simply last longer when in use.
Buy a Fling-ama-String for your feline, they'll love it! After you've plugged the third set of AA Batteries in it, you'll be back here for sure!
This modification will make a great toy quite economical!
Here's Gracie, playing with her Fling-ama-String:
Here it is... shown in a mirror so you can see both sides....
Step 1: Parts Needed
Radio Shack will sell you 3 D Cell battery holders (#270-403a) for $1 each. You'll need a hook for the doorknob- so those rubber coated bicycle hooks from the hardware store will work well. While you're there, go to the electrical aisle and there you will find an Intermatic 15 Minute Mechanical Timer (part # FD15MWC). The shown alligator connectors are optional. You'll also need a scrap of wood, some small gauge 2 conductor wire (2 feet would be nice- you can use speaker wire or scrap extension cord)
Step 2: Size Up a Piece of Wood
A Small piece of plywood, 4"x6", maybe 1/2" thick will do. Here are the four main parts all laid out. Cut it to size. (or not)
Step 3: The Wiring Explained
Line up the three D Cell Battery Holders as shown. We are going to wire these to produce 4.5 volts, that is... The total power of all three batteries... 3 x 1.5 volts
We're going to connecting the BLACK wires to the RED wires, just like shown here.
This is called "SERIES" wiring. http://en.wikipedia.org/wiki/Series_and_parallel_circuits
Step 4: The Timer Added to the Circuit
This image will show how the timer is added into the circuit. Notice the writing on the image... it will be a good guide for connections.
Step 5: Mount Hook
You will find that pre-drilling a hole in the wood before screwing in the hook- that will keep it from splitting. A good excuse to own a power tool!
If you want to go "low tech", you could also use a small "eye" hook (no need to pre-drill a hole), and then loop a piece of cord through it- to hang over the door knob. You don't have to get as fancy as this bicycle storage hook, but for 40 cents, why not?
Step 6: Connecting the Wires- Various Methods
This is not a high voltage deal, so there is no danger or getting zapped. You could just twist the wires together and be done with it. You could tape them. You could solder them (Oh boy, another excuse to buy a tool!) You might use a fancy connector- or you'll find great use for "shrink tubing".
Shrink tubing is easy to use. Twist your wires together really well- I like to then bend the joint over in a hook loop. Then cut a piece of tubing to fit. Shrink it down with a heat source. Another cool thing you can get at Radio Shack.
Step 7: Secure the Components to the Board
I used two 1.5" drywall screws to tie the timer to the board. I then used two 1/2" drywall screws to tie each of the three battery holders to the board.
I tucked the wires up and behind the battery holder to keep it neat.
Step 8: What It Should Look Like
This is what mine looks like, yours may be similar. Not to worry- it will work just fine.
Let's put some batteries in....
Step 9: Connect the New Power Supply to Your Fling-ama-String
Turn the Fling-ama-String to the ON position. Turn your newly installed timer to the ON position. There will now be power supplied off of the end of your power leads. It's 4.5 volts, so don't get too concerned- but don't let them touch or they will cause your batteries to wear out.
Touch the POSITIVE (+) RED lead to the flat coiled-up spring in the upper right hand corner of the Fling-ama-String battery case.
Touch the NEGATIVE (-) BLACK lead to the cone shaped spring in the lower left corner of the Fling-ama-String battery case.
The toy should operate and the band should be going in the proper direction. If not, reverse the wires at the battery compartment springs in the Fling-ama-String battery compartment.
Me? I just smoosh the wires into the springs. You can wrap the wires around the sprigs, or you can get real fancy and get tiny "alligator clips" to bite them with. Unnecessary, but another Radio Shack item for $1.
Step 10: The Battery Door Cover
It will need a little slot cut in it to allow the new power wire to go through.
I was too lazy to go to the basement for a file, didn't want to bother with my Swiss Army Knife, so I used a nail file that my wife left laying around. Just cut a notch. If it's snug, that would be good. That way, it won't allow any tugging of the wires from the outside. That might cause the wires to come off the springs- and kitty wouldn't want that!
Step 11: Set It Up
Hang the new power supply off of the back side of the door. The new power cord runs around the door.
You would never want to do this with a regular household current power line, but a tiny 4.5v line is not dangerous. This narrow door frame gap is why you might want to buy and use multi strand "speaker wire' while you're at Radio Shack. It's thin and very flexible. If you use scrap lamp cord (extension cord wire), it's a lot thicker- so your door's closing might be blocked.
Step 12: Sit Back in Wonderment
Give the timer a little twist and pretty soon, your kitty will know what that sound means!
You'll find that these D Cell Batteries seem to last forever (certainly when compared to leaving the original standard 3 AA Batteries run down if you leave the room).
Remember- to operate, the switch on the Fling-ama-String should be left in the "on" position. Control the power to the unit by a twist of the timer.
Kitty likes Fling-ama-String!