Thread: Prop Alarms

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I was going to go talk to some auto electronics shops today about this, but wanted to see if anyone on HF had already made one. I was wanting to have an inexpensive prop alarm system made up. I'm looking for something small and simple, consisting of a couple tilt sensors, an alarm of some kind, and a power supply like a 9-volt battery. I'm looking for something I could put in a prop and it would sound an alarm if it's moved and gets tilted.

Any ideas or suggestions?

They have personal alarms that when the strap or key ring is broken apart the alarm sounds. you could use this by attaching one end to the prop and the other to the
ground. This way when someone moves it the alarm will sound.

They use something similar on fire extinguishers in collage dorms.

What I'm thinking is taking a smoke detector apart, replacing the smoke sensor (which I believe is just a switch that closes a circuit when smoke is detected) with a tilt sensor, and rebuilding the components into a smaller assembly. Most of a smoke detector is air space, so I'm thinking I can make the device much smaller. It would run off a 9-volt battery for more than enough time to cover when a prop is outside for display, and I think wouldn't need a reset mechanism as the alarm would sound when the tilt sensor closes, and would shut off once the prop was upright again. Plus a smoke alarm buzzer is plenty loud.

Smoke detectors aren't simple contact switches and not good to modify. (the sensor is even radioactive)
The simplist cheapest alarms are small magnetic window alarms made for apartment dwellers, they are dirt cheap, can be found at nearly any big box store and run on batteries.
http://www.amazon.com/W2-Corporation...7311041&sr=8-5

Originally Posted by ZapWizard

Smoke detectors aren't simple contact switches and not good to modify. (the sensor is even radioactive)
The simplist cheapest alarms are small magnetic window alarms made for apartment dwellers, they are dirt cheap, can be found at nearly any big box store and run on batteries.
http://www.amazon.com/W2-Corporation...7311041&sr=8-5

Agreed. I have even seen these at a local dollar store. The internal reed switch is soldered right onto the surface of the board and can be easy replaced by a set of leads for using a remote switch or even using a "pull apart" type connector on the end of the wires. You solder a loop of wire onto the one side of the pull apart connector and attach that to the prop. You then connect the sounder to the ground (or vice versa) when the thing gets lifted, it pulls the plug and opens the circuit causing an alarm. If you install the main unit in your prop, it will be screaming away as they are running down the street with it. Don't think anyone is going to want to deal with that.

These bell howell door alarms are pretty loud.. all self contained.. If magnet is removed it goes off..
http://www.google.com/search?hl=en&r...w=1280&bih=939

These sound like some great suggestions. I knew there had to be something on the market that could be adapted. I'm thinking I can modify one of these alarms and install the sensor into the feet of my figures so when they are picked up the alarm goes off, and put the alarm into the body so it's not something that can be easilly removed/disabled, or seen because of wires. I can also rig a power on/off switch and hide it so I can activate the alarm only when it's outside.

Great suggestions guys! Thanks

http://www.asseenontvjunkies.com/Bel...on_p_2128.html
I have some of these.. and they are loud....

Years ago, i thought about converting old/used smoke detectors as well. I have saved up about ten of them, but haven't done anything with any of them yet(even after I lost a few tombstones a few years back).

My thought was to use the "TEST" feature that is normally part of the original circuit. This is usually a plastic button on the cover that simply presses a contact together. I figure if you bend the contact enough to make constant contact and sound the alarm, you would just need something between them to isolate it when in place. Tether that the isolation strip to the ground. When the prop is moved the tether pulls out the isolation strip.

I was looking at tip sensors as my figures are too heavy to pick straight up and leave with, so a thief would need to tip over and carry them somewhere, but putting those clips in the bottom of the feet should do the same thing. My goal is to have someone pick a figure up, activate the alarm, then put it down and leave, and have it all happen internally so there's no wires that can be tampered with to disable the alarm.