This essentially turned Holmes’ design into the first modern fire alarm. Burglar alarms get triggered in different ways.

[Jeff Sandberg] demonstrates that ably with his project to use ancient 1990s burglar alarm sensors in his modern smarthome setup. The sensors in question are from an old GM Interlogix security system.

He thus set about working on a burglar alarm that would fit his unique requirements. An ESP32 is the heart of the operation, paired with a long-range LoRa radio module running at 868 MHz.