Perimeter Alarm, Trip Wire, Booby Trap




Introduction: Perimeter Alarm, Trip Wire, Booby Trap

I have a building about 300 feet from my residence. This building is a shed that houses lawn equipment, snow removal equipment, a pickup truck and misc. tools and fuel. The shed was built for storage and is not easy to secure (there is a 1 foot gap between the side and the ground). It has no electrical power and is not visible from the residence. I needed a low cost alarm that would alert when the equipment is being disturbed. I have two dogs that alter when they hear loud noises such as a gun shot.

After doing some research I found that a 12 gauge shotgun shell fits in a 3/4 inch black pipe to make a make shift barrel. (the pipe is welded and the inter seam may have to be filed for the shell to completely enter he pipe) I also learned that the pipe is not strong enough for repeated shotgun blasts, so I decided to use just the primer as a noise maker and not use a complete shell with powder. I wanted to make an alarm not a pipe bomb.

I wanted a simple device to make, so I went to the home center and picked up the following items.

4 inch long 3/4 inch black pipe nipple

PVC 3/4 inch threaded female coupler to 3/4 inch glue fitting

PVC 3/4 inch to 1/2 bushing glue fitting

3 inch long 1/2 PVC pipe

PVC 1/2 inch glue fitting to 1/2 female threaded fitting

PVC 1/2 threaded plug

4 inch 1/4-20 bolt and nut

Spring .035 wire 6 turns per inch 3/8 diameter 3.25 inches long (this was just cut off a 12 inch length of spring)

8 penny nail (end blunted to reduce piercing the primer)

1/2 inch dowel 1 inch long wrapped with masking tape to make a slip fit in 1/2 pipe.

Pop rivet pin to secure firing pin.

All these items were purchased for less than $10, (researching the internet I have got the price to just under $5 each)

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Step 1: Machining (hole Drilling)

There are 3 holes to be drilled

Drill an 1/4 inch hole through the center of the plug

Drill an 9/64 hole through the 1/4-20 bolt to secure the striker, the location is found by assembling the spring on the bolt and inserting it into the plug and then while holding in a vise with the spring fully compressed mark the bolt on the bottom of the plug. Grind a flat on the bolt where the hole will be drill. Using a vise on the drill press, align the bolt to the drill bit, a small ruler between the drill bit and the bolt will locate the center of the bolt by acting like a seesaw and when it is centered the ruler will be horizontal. Remove the ruler and drill the hole.

The last hole is a clearance hole in the dowel for the 8 penny nail.

Drill and 1/8 hole in the center of the dowel for the firing pin (nail)

Step 2: Glue Plastic Pipe

Now glue the female coupling, bushing, 1/2 pipe, and female coupling together.

Step 3: Preparing the Empty Shotgun Shell

Get a spent 12 gauge shotgun shell and remove the used primer.

Purchase a box of new primers, (available at sporting goods, gun shops, Bass Pro, Cabela, Midway USA, even some Walmart carry them with the black powder firearms ammunition)

Insert the new primer in the shell and press in place (an assist from a dowel and a mallet or a reloading press may be needed)


Primer only.

Step 4: Assemble Firing Pin, Striker, and Release Pin

Insert firing pin into 1/2 pipe.

Insert spring onto bolt and insert through hole in pipe plug attach nut to keep assembly together

Screw pipe plug into pipe assembly

Secure in vise and cock striker, insert pop rivet Release Pin

Attach cord or string to release pin

Insert primed shell into black pipe and screw onto plastic pipe

Mount to a fixed object near to the monitoring point with conduit straps

Run trip wire (string) using eye hook to change direction

Then wait for the alarm to be activated



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    7 Discussions


    2 months ago

    Instructables was not intended to clearing house for dissemination of immoral criminal activities or proliferation of dangerous heretical renegade dissident ideas !
    Your names and IP address's are ALL Flagged by National Security Operations Center and submitted to the NSA watch closely Targeted individual list.
    If Your using a TOR browser You are EXTRA Flagged.


    1 year ago

    Just what I needed have made two will make more latter but it worked, I also added a sign stating amo is not as freely available so don't expect a waning shot. had to move the first one to low and the cat flew over the wall want him bact as good ratter.



    3 years ago

    I really don't understand the concept of not posting anything that could potentially be modified to hurt yourself or others. This kind of thing happens all the time. What are you pro censorship people hoping to achieve? I'm serious. Would someone please explain this to me?
    When I was a kid playing involved the back door opening and then coming home when Mom screamed that dinner was ready. No play dates, no sterile environments and no constant supervision. The recipe for gun powder came in the toy chemistry kits. There were no secrets no taboos to tempt curious minds. Ok not entirely true, for some reason sex was off limits so we had to hide our playboys under the mattress.But here's a interesting statistic: in France where sexuality is on TV and more open, there are less sex crimes per capita than the US. As children, we were taught the dangers and the correct safety measures. We had a healthy respect for everything that could harm us including people. Today kids are so sheltered they have lost their natural instinct for self preservation. When I was a kid we knew when someone was a possible threat because we were told what a pediophile was, how they operated. We knew what to look out for and what they wanted. Not just a general, "don't talk to strangers". It was explained to us in detail. We didn't get colds, infections, allergies etc etc etc with the same frequency as kids today because our immune systems were being used every day. Like a muscle we exercised it often by playing in the dirt, the rain, and snow. My point is that open and honest dialogue on any subject. Even the ones that make you uncomfortable is preferable to censorship. Take the mystery away and the impulse to "experiment" without proper knowledge is reduced.
    Thomas Jefferson said:
    " Any man that is willing to give up even a small amount of his liberties for a measure of safety, deserves neither."
    I was serious about wanting to hear a rational argument in favor of censorship.
    Happy Holidays everyone. May you and your loved ones have a Safe and Wonderful New Year.


    3 years ago

    OMG! ? Really? If this is the worst recipe/instruction you can find on the WWW then we live on different planets. Remember John Phillips? No? He was the Princeton junior that designed a workable A bomb using info found on the web and the public domain. He was missing a critical piece of information on the explosive used in the implosion sphere so he called DuPont and they gave him the specs over the phone! Yes, it's all true. Read the book it's called "Mushroom". Almost any instructable can be modified to create something that could potentially hurt someone. What about making a knife from a saw blade. OMG! Take it down someone might get cut? People have a uncanny ability to take the most innocuous item and figure out how to hurt themselves or others. The Paris terrorists used a truck, the Boston marathon bombers a pressure cooker. Should we ban motor vehicles and cookware? I say people hurting themselves or others is unavoidable. So please, stop trying to censor the world.


    Reply 3 years ago

    bravo, sir


    Reply 3 years ago

    I'm with you, 97bravo20. Heavens above! When I was a kid, you could get chemistry sets and wood burning kits. Now everything has rounded corners and packed on foam.

    And yes, I remember the John Phillips thing, though I couldn't have told you his name before you mentioned it. BTW, you can buy uranium on Amazon. Let the fun begin! :-D


    3 years ago

    OMG, DON'T use a dowel and mallet to insert any primer. Otherwise you will one day set off the primer. Reloading presses are designed to not create a situation that could detonate a primer when reloading. I would never ever try to insert a primer in anything with a dowel and mallet. You would be much better off taking a new shotgun shell and cutting the top off and dumping out the shot to use the shot-less shell. JMHO