Burglar alarms have a circuit that is activated by a switch, which is triggered whenever a door or window is opened. The most ...

[Jeff Sandberg] demonstrates that ably with his project to use ancient 1990s burglar alarm sensors ... sit on doors or windows. They use magnets and a reed switch to sense if the door or window ...

[Anders] tipped us off about his hack that re-purposes a smoke alarm as a burglar alarm ... of wire is secured to the frame and jam of a window. A paper clip completes the circuit by pinching ...