|Project by Airspeed||posted 09-07-2013 08:25 PM||1697 views||1 time favorited||12 comments|
My wife works at a golf course, a few months ago someone stole her tip jar with about $120 in it, she found the empty jar in the men’s bathroom, happened again a week later so I built this little box with an alarm built in. The alarm sounds if the box is picked up or the lid removed. It also sounds if its tilted. I put a small switch in the bottom and one under the lid, if someone figures out to hold the button in another alarm will sound when it’s tilted, I made a tilt switch out of some aluminum sheet, I cut two 2” discs, pounded them into a conical shape, put a small steel bearing between them, I made a rubber gasket between the two discs to keep them insulated from each other. I attacked a wire in line to these discs, when the box is tilted the ball bearing rolls to the outside edge and closes the circuit. It’s very sensitive, a tilt of one degree is enough to roll the bearing.
I recessed the power switch in a way that it takes a special key to push the button. I was going to by a keyed switch but I wanted to use stuff I had on hand. The lid is held on with neo magnets
About a week after she took it to work she caught someone trying to grab it, well she didn’t catch them but the alarm went off while she was in the back room, by the time she got out front the perpetrator had made his (or her) escape, the money and box were still there though!