I made a Burglar Alarm for under 5 bucks, and items I found laying around the house! No soldering required. (soldering optional)
I uploaded this video to the video section as well. Check out my video below:
Step 1: Items you will need to build your $5 Dollar Burglar Alarm.
4x4 piece of card board,
3 regular size rubber bands,
1 jumbo paper clip,
3 regular size paper clips,
1 push pin thumbtack,
1 AA battery,
6 to 8 inches of thread or kite string,
1 spare piece of thin cardboard,
An aluminum pie pan,
"AA" Battery Holder from Radio Shack (270-401A),
3VDC Mini Buzzer from Radio Shack (273-053A).
Step 2: 2nd Step
Place AA Battery Holder on the 4x4 piece of cardboard, and punch 4 holes around the battery holder.
Step 3: Step 3
Push a rubber band through the bottom hole, and pull it through the other hole. Secure the rubber band on the other side with a paper clip. Do this for both holes.
Step 4: Step 4
Insert your battery in your AA battery holder, and slide the two rubber bands over the battery holder.
Step 5: Step 5
Place your clothespin on the piece of cardboard. Now poke 2 holes on each side of the clothespin.
Step 6: Step 6
Push a rubber band through the hole, and pull it through the other hole. Secure it on the other side with a paperclip.
Step 7: Step 7
Slide your clothespin under the rubber bands.
Step 8: Step 8
Place your mini buzzer on the cardboard. Use a thumbtack to poke 2 holes for the buzzer (image1). Unfold your jumbo paperclip. Push both end of the paper clip through the holes of the buzzer (image2). Now bend the paperclip against the cardboard to secure the mini buzzer(image3).
Step 9: Step 9
Take your clothespin out and place it on the aluminum pie pan. Trace a pattern (with a pen) around the top half of the clothespin(image1). Cut out the pattern into a boot shape (image2). You'll need two of these. Poke a hole into the tip of the boot with a thumbtack (image3).
Look at image 4 for the end result.
Step 10: Step 10
Now superglue or tape the aluminum boot to the inside of the clothespin (I used scotch tape). Slide the clothespin back inside the rubber band (image2).
Step 11: Step 11
Cut a small square from the thin piece of cardboard (image1). Poke a hole in the square with your thumb tack (image2). Pull your thread or kite string through hole and tie a knot (image3). Now tie a knot around the thumb tack (image4).
Step 12: Step 12
Insert the black wire from the AA batter holder through the aluminum boot hole (image1). Insert the other black wire from the mini buzzer through the aluminum boot hole (image2).
Step 13: Step 13
Place the piece of cardboard between the clothespin.
Step 14: Step 14
Now tie (or solder) the two red wires together.
Step 15: Step 15
Put some duct tape on the bottom of your new alarm (image1). Now your $5 Dollar Burglar Alarm is now complete (image2)!
Place the $5 Dollar Burglar Alarm on your door (image1). Push the thumbtack into the wall (image2). Now open the door to test it out (image3)! The aluminum boots in the pin makes contact when the cardboard is pulled out. This is what sets off the alarm!
Step 17: Step 17
You can also use this as a trip wire alarm! You might want to secure the $5 Dollar Burglar Alarm with thumb tacks if you use it as a trip wire alarm. Be sure to check out the video version of this step-by-step instructable in the "Intro".
***NOTE*** You can always use a louder buzzer for this project. Good luck!!!
Johnny Rock Stah