Fuzzyred's Marvelous Reading Nook

The latest smoke detector to howl pointlessly into the night sends out 11.3V DC onto the signal pin when triggered but running off batteries. I suspect that’s 12V nominal, and it probably delivers 12V when operating on AC power.

Most importantly, it’s not like… 500mv. Or AC. Or complicated. It’s plain, simple DC.

When acting as a non-reporting satellite node, it triggers when receiving 4V DC on the signal pin (4.0 exactly), and that voltage is polarity sensitive. -4V doesn’t trigger the alarm.

Checking for DC on the signal line, I get functionally nothing. 20ma DC at most, and even that’s something I’m picking up out of noise floor shift rather than direct measurement.

(Yes, I checked for AC as well. Still functionally nothing.)

My thought was that if the signal line was somehow floating in whole number volts (for whatever reason) than maybe somehow the right RF noise could kick it over.

The problem with that is that I can now also confirm that non-detecting units go off exactly as long as a detecting device keeps saying it’s detecting by putting voltage on the signal line. If that voltage goes away, so do the satellite alarms – and immediately.

And that’s not what happens. We have to manually intervene and shut the alarms off ourselves.

The reason I paid meaningfully more than baseline for this particular set is that they report exactly which detector went off and why. That way, if it were the signal line somehow triggering the alarms, none of them would claim to be the originating unit; they’d all report it came from the signal backbone.

But they don’t. There’s always a unit claiming to be the active detector and it’s always smoke (and there is never actually smoke), and none of them shut up until we shut off that unit, which sometimes seems to require removing it from power.

So today’s afternoon check was basically just another way of confirming what we already knew, and I guess I’ve done that now, but…

All that does is get us right back to where we started, which is, “we have alarm after alarm after alarm of different makes, methods (ionisation, photodetector), and models which just in this house are determined to go off randomly, usually but not always at night, for absolutely no detectable fucking reason, and then pass self-test just fine afterwards.”

And no, regular cleaning – even weekly cleaning – does not help. I do all the things. None of it stops the problem.

If you’re new to this adventure, I have heard this exact same story from many other people at this point – though nobody I’ve talked to has said they’ve literally taken metres to the signal wires to verify that way.

Regardless, I know it is not just us.

What I’ve been told from others who deal with this is to RMA individual units that trigger randomly one at a time until you end up with a set that doesn’t. And I guess that’s what I’m gonna do, but

holy shit, team

holy shit

this is the opposite of fire safety

this is the opposite of how anything like this should ever work, I mean

what if all the RMAs are getting you are a set that won’t go off even when they should?

but whelp

guess i’m gonna find out

’cause this sure ain’t workin’.

Posted via Solarbird{y|z|yz}, Collected.