The Boards
The goal is to have my phone buzz/get an email when the smoke alarms in the house go off. The alarms I have ar Kidde brand, dual smoke and CO detectors. All are wired on the same circuit with A/C power, and have a signal wire tying them together as well. I bought the Kidde interface boards, which tie into the 3 wire interface on the alarms, and toggle a relay when any of the detectors alarm.
[pictures of alarm P/N, and relay boards here]