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(116 votes) Published: Sep 06, 2006 4:07 a.m. In 12 Favorites Lists Viewed 1381 times
This is a basic perimeter alarm that is set off by a tripwire and battery powered electrical system. The uses are as varied as your imagination, such as paintball games, home security, that "special garden" or anywhere you want to be alerted of an intruder’s presence.
The trip wire can be as simple as a straight line across a path or a semi-circle or even full enclosure.
Items need:
Bell wire (16-20 gauge)
Clothespin (the gator jaw type)
Plastic square (I’ll explain other options)
Stake or an anchoring point
Dry Cell battery or a 12 volt car battery (for long term use)
Model rocket igniter
Waterproof fuse
Alarm (some ignited type or a car horn)
Thread
12 lb + fishing line
Shoe polish (black) or camo face paint
Plastic sheeting/plastic wrap
If I missed anything, you’ll figure it out as we go along as they would be minor things.
The principal is to have a tripwire in use that when a person, dog or deer crosses, it sets off and completes an electrical circuit (D.C.) that sets off an alarm.
I have made alarms out of car horns using a larger 12 volt car battery, but the ones made with a fuse detonated (Legal) firework is very effective. Just be sure to make certain no fire danger happens when it goes off.
Here is a layout of a pathway setup with a "firework" alarm.
It’s pretty easy and self explanatory but we’ll go over the details anyways.
You take the wire (insulated) and strip off enough to wrap around one of the single ends of the clothes several times. This wire leads to the battery. The other single end of the clothespin is wrapped several times with bare wire from the other end of your wire so that if the clothespin is closed, a circuit is complete.
The plastic can be as simple as half of an old credit card or something similar with a hole punched in one end. This will act as an insulator and keep the circuit open until something hits the trip wire. Your fishing line is attached to the hole and using shoe polish or camo face paint, you can hide the line by rubbing some between a leaf or your fingers and running it along the line.
The other end of your fishing line or tripwire is secured to a stake, tree or wrapped around several "stakes" to enclose an area. It takes little pressure on the tripwire to pull the card from between the clothespin and complete the circuit.
If you’re using a car horn, you’ll need a 12 volt car battery to make it work. This horn can be placed in the electrical circuit just about anywhere you want. Use a small voltmeter to test your circuit BEFORE hooking up your "alarm". Safety first!!
If your area allows a pyrotechnic to be used, such as a paintball game or on your own property, you need to make a different alarm in the circuit. Take a piece of cannon fuse and using a razor blade, carefully slice it so you have an open end. Insert the rocket engine igniter between the halves and wrap it with thread a dozen times to insure the igniter will light the fuse when the circuit is tripped.
Splice the other end of your fuse onto the fuse of whatever you decide to have ignited. I’ve used a loud report roman candle before, set up 10 yards (or meters) away, pointing at the place in the trip wire most apt to be hit. Scares the hell out of whatever set it off!!!!
You can see how using your imagination just about anything can be set off or if using an electrical device, like a light, you can have a silent perimeter alarm.
Aside from inside a house use, you’ll want to keep things safe from the elements. Cover your battery, clothespin assembly and alarm in plastic clothe or wrapped in a food plastic wrap paper. Water can be a real bad thing. You can spray paint a flat color on the plastic coverings to camoflage them. The battery can be placed on a wood or plastic board, buried in the ground and covered with plastic to keep moisture out.
Use your imagination on disguising the electrical wire, bury it, paint it etc. and the trip wire.
This is an easy to make perimeter alarm and can save you, property or just be fun to have a friend stumble onto!
Sep 06, 2006 1:29 pm - Had no idea this was posted before and it’s something I did learn in the Rangers. I’m sure there are variations of it in a lot of places though. Just trying to pass info along...
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