• rumba@lemmy.zip
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      3 hours ago

      They run off batteries, using either isotope decay or light sensor (or both)

      I actually have one hanging off my ceiling right now, it’s battery was fine, but it tripped likely due to dust or a spider on the optical sensor. It went off at 2am, network sent them all off, took me 10m to find the right one I wasn’t about to just blow it out and out put it back on the ceiling :)

    • Natanael@infosec.pub
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      8 hours ago

      Depends on model. Almost all older ones does (using radiation from the isotope to electrically charge smoke particles that pass through, which then can be detected by a sensor).

      Many newer ones are optical.

      • SaveTheTuaHawk@lemmy.ca
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        5 hours ago

        The A-241 does not charge the particles, it ionizes the air in a small chamber that allows a steady current. Any smoke particles disrupt these currents to set off the alarm.