Homemade Alarm System Doesn’t Lack Features

alarm system

To many of us, our garage (or workshop) is probably one of the most important parts of the house. If a burglar broke in, we’d likely be more worried about our tools! [Ron Czapala] decided he needed an alarm system in his garage to keep his stuff safe, so he decided to build one from scratch.

The system makes use of a Parallax 4×4 keypad membrane, a MCP23008 port expander, a Parallax Propeller, a LCD screen, and a few switches to represent future magnetic reed switches located in the door and window.

Using circular buffers, the propeller has several states for monitoring the garage.

  • Not armed — ignore all sensors
  • Armed — system will react to changes in the sensors
  • Exit delay — system has been armed, 45 second countdown has begun to allow you to exit the garage
  • Window trigger — if the window is opened, the alarm will go off immediately (siren and strobe light)
  • Door trigger — alarm will go off in 60 seconds if correct code has not been entered on the keypad

For a complete demonstration, check out the following video where [Ron] explains it all!

[Read more...]

Thwart robbers with an old smoke alarm.

[Anders] tipped us off about his hack that re-purposes a smoke alarm as a burglar alarm. Unfortunately, he came home in the middle of a burglary but wanted to be ready the next time someone tries to break in. By cleverly patching into the test button on an old smoke detector he created a circuit-trip alarm. One side of each piece of wire is secured to the frame and jam of a window. A paper clip completes the circuit by pinching the two bare conductors. If the window is opened the connection is lost and the alarm sounds.

We see a few problems with this system. First off, never hack your ONLY smoke detector, you are putting lives at risk by doing so. But [Anders] says he’ll have a replacement detector and since these things need to be replace every ten years or so, chances are you can find an old one kicking around. We’d recommend disguising the case so that people aren’t confused about it being a smoke detector. Secondly, he’s mounted the alarm right in the window frame so most likely an invader will just smash the thing to bits.

Anyway, it’s still an interesting reuse of these ubiquitous, and life-saving, devices.

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