There’s a huge market for 433 MHz alarm system hardware out there, from PIR motion detectors to door and window sensors. If you want to put them to work, all you need is a receiver, a network ...

In the microcontroller era today, Arduino is more than just a tool ... is used to measure the light level. The alarm system is triggered when a “Logic High (H)” level signal is detected at its sensor ...

You can connect any intrusion detection unit (such as a light fence or a motion sensor) to the input connector J2. Note that an active-low (L) at pin 1 of connector J2 triggers the security system ...

Those sensors are finicky and a few problems during testing prompted him to look at a redundant system. Right now he’s experimenting with adding an optical ... can see the Arduino Leonardo ...