Wary of intruders in the night? Don't feel secure knowing that there are expert lockpickers prowling the neighborhood? Perhaps you live in an apartment and you don't trust the landlord because he seems to watch you? Well here's a simple solution for your problems (at least in your room).
I apologize for the crappy photos and for the fact that I kind of broke my smoke detector's alarm so until I find the other one that is wandering around the house somewhere, I have created this temporary set-up to give you all the plans on how to create this alarm.
1. Disc magnet
2. Small flashlight
3. Alarm (old smoke detector, alarm clock, etc.)
4. Metal right angle (or plate)
6. Conductive foil
7. 9v battery
8. Electrician's tape
9. 9v clip (optional, but easier)
10. Capacitor (optional unless you need it)
Step 1: Only the beginning...
Ok, confession time. I broke my smoke detector's alarm, so I am unable to show it to you correctly (though I did salvage parts for other projects). Hopefully you understood the intro photos in how this works. So I'm showing it using an old speaker (which I'm converting later, so I didn't mind cutting the wires).
1. Cut the wires to your alarm (or solder some on, if neccessary) and strip the ends.
2. Take the cover off of your flashlight and keep only the plastic lens holder (don't keep the lens)
3. Put your disc magnet into the plastic housing. Should have enough room to move freely, but not enough to slide or flip around.
4. Now take your 9v battery and put a piece of electrican's tape on it.