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Inexpensive perimeter alarm

Security after TEOTWAWKI (The End of the World as We Know It) will be important. Depending upon your location – methods used to be aware of “trespassers” will vary. For those on a budget – I have discovered a very inexpensive method to provide a decent alert when  a passerby trips the alarm.

The main component is a window/door alarm that can be purchased at your local Dollar Tree for $1.00 each. These alarms are very loud (90 decibels). They contain a simple on-off switch and work via a corresponding piece that when moved away from the main unit – activates the alarm. Below are the step-by-step instructions on how I made one:


STEP ONE (below): Purchase the alarm – often available at Dollar Tree and other “fine outlets”.

STEP TWO (below):Obtain a piece of wood – such as the 2×4 pictured – and add two attachment loops for mounting.


 STEP THREE (above): Remove the battery compartment door and unscrew the small screw which holds the top and bottom half of the alarm together. You will need to find a longer small screw to replace the screw you just removed in this step.

STEP FOUR (above): Screw the longer screw into the hole all the way through the unit into wood to securely mount the alarm to the board. DO NOT OVERTIGHTEN  – you want the screw to be snug against the alarm.

STEP FIVE (below): Making sure the switch is in the OFF position – install the included batteries.

STEP SIX (below):I did not provide a very good illustration – but the bottom-left corner of the second piece needs to have a small amount of material carved away with a sharp knife or file. This will allow the piece to swivel away from the main unit. After carving material away from that corner – attach the 2nd piecewith a small screw. You need the second piece to be loose – so do not even make the screw snug.



FINAL (above):

Of course – the alarms can be used for their intended purposes – mounting on doors and windows, which can be useful to keep people out of your food storage, Medifast coupons collection, weapons, and water supplies.

The unit is basically complete. This design allows the board and alarm to be mounted to a tree/object via bungee cords. A fishing line or similar thread can be attached to the empty hole in the 2nd piece of the alarm and attached
to a tree or some other object to create your perimeter line. Then, if someone were to walk into the line, it would pull on the 2nd piece
and cause the alarm to sound. A small rubber band or a piece of double-sided scotch tape may be needed to hold the two pieces together without prematurely setting off the alarm.

 Summary: This is but one design and depending upon your application can be changed and adapted. Painting to camouflage it may be needed to prevent it from being noticed. The unit is not weather-proof  – so a small “roof” can be mounted over the alarm using  a 20-oz soda bottle cut in half length-wise. You do not want to cover the unit as that will reduce how loud the alarm is when activated.

Of course – the alarms can be used for their intended purposes – mounting on doors and windows.

A lot of possibilities here -


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9 comments to Inexpensive perimeter alarm

  • Excellent idea, and on the cheap too!! Does not look to hard to install. Any extra help keeping thing secure is always helpful.

  • irishdutchuncle

    bummer about the newsletter.

    my wife has purchased a number of these alarms over the years, they work ok. we have one on the apartment door. if we were on a lower floor i’d put them on the windows as well. they have lots of nifty gadgets at dollar-tree. pity about their name though, i always heard that “dollartree” was a sin.

    the “survivors will be shot again” sign would be even more effective with a few outward facing bullet holes through it. (performed safely at a firing range)

  • Rourke

    irishdutchuncle –

    Good idea about the sign!


  • freeholder 1787

    As much as I love the sign idea – I’d rather not have some over-zealous prosecutor showing it to a jury, explaining that I was just champing at the bit to shoot me a tresspasser for a trophy. Or some soulless barracuda of a civil lawyer making this guy’s widow a rich widow at my expense. Same for “Beware of Dog” signs – it shows that you though there was a good chance that the dog would bite – and therefore you’re responsible. Discretion is the better part of valor.

    As for the alarms – I’ve used them – and they are well worth the cost, time and effort.

  • Beprepared

    Congrates on the mention in survivalblog… readership should go through the roof!

  • Rourke

    Beprepared –

    Thanks – glad to see JWR is checking out my blog.


  • My alarm system:

    -Two very loud chihuahuas
    -One friendly to a fault but not afraid to bark at intruders mini doberman/pinscher/whatever

  • Sounds like this should work as a basic alarm. And my kind of price too :) Thanks for posting the instructions. I liked the sign as well.

  • Hat Bailey

    I like the sign my friend has posted outside his gate. “UNDER NO CIRCUMSTANCES WILL ANYONE REMAINING OUTSIDE THIS FENCELINE BE FIRED UPON” Can’t be construed as a threat, but sure makes a person think twice.