Instructables

Alarming Tennis Ball

Picture of Alarming Tennis Ball
A tennis ball that when activated will sound an alarm. A simple magnet and the remote is used to arm and disarm the device. Once armed only time and the remote can disarm the device. Its great as a way to break the silence. Use it around others to be even more exciting.
 
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Step 1: Materials

Picture of Materials
Materials:
1 - Doberman Security Toolbox Alarm ($15  Home Depot)
1 - Tennis Ball

--- I found a cheap window alarm for $1 at the dollar store, simply removed the batteries and housing from the casing.----
3 -  LR44 Button cell batteries
1 - Casing for 3 LR44 batteries 


-- Stand --
2 - Plastic or paper cups

Tools:
Soldering Iron
Solder - for electronics
Exacto knife or razor knife
general purpose super glue (Picked up at dollar store for $1)
Clamps or device to hold in place while using the saw
saw, preferably one for cutting plastic. 


animan12 years ago
How far away will the disarm/arm button work? also if I threw the ball would it break?
mcguyverzboss (author)  animan12 years ago
The Remote uses radio frequency to arm and disarm the device. I would say about 5 feet it will work. I have tried it at ten feet and it has worked too. Sound wise I have noticed that the alarm sound is significantly less when inside the tennis ball. If you drill minute holes or cuts in the tennis ball the sound will not be as significant.

I would try finding a car alarm kit or some remote activated alarm instead. The device I used has to be activated by a magnet and when the magnet is removed it will sound the alarm. Unfortunately in sense of secrecy it results in the person having to physically remove the magnet and throwing the ball before the alarm sounds. It makes more sense to instead put a remote activated alarm in place of the electronics i chose. You would then be able to sound the alarm remotely as well as stop it without any magnets just the remote.
The sound must be activated when the person throws the ball so that is what I needed. Will it break when thrown? and 20 feet should be enough for my pourpose.
mcguyverzboss (author)  animan12 years ago
If you use a good glue the tennis ball itself should not break on impact. I have thrown the ball many times and it has not broken. The one thing I did find was that the magnetic switch inside the tennis ball would sometimes move from its original position. I would pack tissue paper around the electronic parts to make the fit more snug. It appears that the tennis ball shell absorbs most of the impact and not the electronic parts on the inside. You should be fine throwing it.
Thanks, very helpful