This is my first instructable, however i have considerable experience in soldering and designing odd things like this
The thing that always got on my nerves was that when these go off EVERYONE knows where it is AND that you're using it,
so its not practical for sneaking up on someone, or even pranks where you need to tell when someone is coming.
I will show you how to fix that. i will show the finished product above.
The first step is to gather supplies, the supplies needed are listed below.
the first thing we need is an alarm. The type of alarm we will use is shown above. These are relatively cheap, as i got mine for about $5.00 (on sale) You can buy them at most toy stores.
The second thing we will need is a length of speaker wire (I used 10ft.)
Soldering Iron OR Duct Tape
The last thing is a LED (Light Emitting Diode), you can use whatever color you want.
The second step is to remove the screws to open the battery box, and then the screws behind the batteries, so that we can get inside.
The next step is to desolder the connections for the speaker, FROM THE BOARD not the speaker, and if you don't know how, I have an instructable on that. For those of you who don't have or can't have a soldering iron, cut the wires as close to the speaker as possible. (Sorry about crappy diagram)
Now we split the speaker wire in half (speaker wires have two wires in separate insulation stuck together)
and strip the insulation off the ends and solder it to the speaker connections on the board. (For no solder version duct tape the speaker wire to the other wire from the toy). Now just attach the LED to the speaker wire.
Last step, i'll leave it simple, just drill a hole for the wire, put everything back together, and put some batteries in, and have fun!