Over the last few years, there have been a couple of times when my home alarm has triggered. On both occasions my neighbour has phoned me to let me know and I have had to drive home, in the middle of the night, to sort it out. Every time I get home, the alarm is silent. Not because it has timed out, but because the driver chip has burned out. The first time this happened, I fitted an IC socket, and I keep a pack of spares just in case. But I’ve always felt the circuit wasn’t too great and maybe I could do better.
Recently I acquired a Raspberry Pi and realised that the GPIO ports and Ethernet adapter made this an ideal platform for a web enabled alarm system. The video shows what I came up with, and the next couple of web pages shows how I built the system.