I’ve seen fancy integrations, but any one of some pretty simple hacks could work…
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hook an electromagnet to the 12v DC (ummm… coil one of the wires around a nail… ummm… Not sure if you need resistance to avoid a hot short circuit or whatever…) and use that to trigger a basic cheap magnetic contact sensor. I’m only half goofing… This would absolutely work, I just forget my Electronics 101 regarding the “load” part of this circuit.
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use the 12v to flip a DC relay, whose contacts are soldered to a cheap ZigBee or Z-Wave panic button or the dry contacts available in certain Monoprice Contact or Tilt Sensors… (or just short across the sensor reed).
What’s wrong with using a dry contact sensor?
Or be fancy and use an MCU…