God-damned smoke alarms

We have mains-powered interlinked (one triggers, all trigger) ionization-type alarms on all three floors.

There are backup batteries (I think 9V alkaline, can't remember). Never given the slightest trouble. I replaced the whole set which were getting old (15+ years) a few years ago.

The CO alarms wear out much faster.

The OP link indicates an optical sensor.

Opto sensor smoke detector is basically a single-pixel camera. Regular camera module can scan wider angle with more pixels.

Smoke also give out heated particles. Camera module can also detect infra-red range.

In my motion detection scanner, infer-red is more important than visible.

The camera sensor is actually very sensitive to red and infer-red. With proper len filter and luminance gain control, i can detect IR better.

My experience with smoke alarms is that (excluding badly designed units) most false alarms are due to some kind of incorrect placement.

By "incorrect", I don't mean following all the rules - often one must violate these rules. My specific example is the detector closest to the kitchen stove, which detector kept critiquing our cooking, at the worst possible moment.

The solution was to relocate the detector to the other side of the doorway at the top of the stairs to the basement. The alternative being to turf that detector out.

There is also a detector in the basement, near but not too near to the boiler, and another at the top of the stairs near the bedroom. These never give false alarms.

All my detectors are made by Kidde, which is a big name in such detectors in the US. The basement and bedroom units also sense carbon monoxide. The batteries are not built in, but by regulation, the unit times out after seven years under battery power, and balks, forcing replacement. I gather that the CO detector element physically wears out.

Joe Gwinn

Do you propose to invite your insurer to comment?

This is your pattern. You think up stuff and people explain what is wrong with the idea. You then continue to debate it rather than to learn about it. Go read about smoke detectors. OK?

I did. The OP posted the link to the optical sensor used in the detector. It detects light detraction by particles, same way a camera would do. In addition, IR camera can detect heated particles from fire/smoke. Yes, i know little about smoke detector, but i know enough about fire and smoke and mirror.

No, they are not. Go read about them and stop posting like an idiot.

You know nothing about detecting smoke particles. Learn or stop posting... PLEASE!

It is a PhotoElectric pair of red LED and sensor. You can just as well point a camera at a red LED.

Sorry, but Rick is right here: it doesn't detect smoke "in the same way a camera does".

A camera doesn't, per se, detect smoke: it detects photons.

The smoke detector is based - in camera terminology - on a single pixel detector, which few would regard as being a "camera"

OK, OK, i am lousy with terminology. So, the question is whether a camera pointing at a red LED will see something different when the ceiling it filled with hot air and smoke particle. May be there is some top-secret photoelectric effect we can't see, with or without camera.

the optical smoke detectors don't look at the LED, the detector cannot see the LED, it looks for light scattered by smoke

Sorry, it's the IRED connected to pin 6 of the chip.

The moon was orange last night. Pretty good smoke detector.

The sunlight outside my office is definitely strange.

Yes, and they are likely detecting light scattering, not transmission reduction. May even be a balanced detector, so light source level has no direct effect, so long as it's adequate.

This is way more sensitive than any camera.

Joe Gwinn

I wish I had popcorn. This is going to take a while.

If it is sensitive enough, it will. The typical consumer camrea, however, will not. I've set off smoke alarms with kitchen accidents that wouldn't have been visible (let alone reliably) with your proposed LED / camera setup

Quite the opposite, its bottom-primitive. Just read up on optical smoke detectors and then shut up. Or even better, test your camera / smoke detector side by side in varying ambient conditions and repost back here. If you don't know how to trigger the test, a toaster with a broken timer that doesn't turn off automatically works wonders for smoke generation.

You do not have the slightest idea about the configuration of LED and photodetector, do you? If you are unable to read English, why don't you take a hammer to a smoke detector and FINALLY FIND OUT how it works?

Maybe the detector has gone bad. the ones here died all after a year or so.. Emitter and detector are at 90 degrees inside some kind of plastic enclosure.

When they all age to the point of failure, that majority vote won't help.

So they no longer make those smoke detectors which would yield two nice 241Am sources when dismantled? What a shame.