'Mysensor' a smoke detector with sound detection

  • @ileneken3
    I want to detect when a smoke detector is sounding an alarm without using AC power, and without using power from the detector itself. I currently detect an alarm (really, any loud sound) using the standard KY-038 module, like this:


    But this can't be used for a battery application because the KY-038 has a LM393 on it, which draws .4 ma.
    I ordered a LMV393, which is more suitable for battery operations, to replace it. But I'm not sure if that would work, or if I could manage the SMD soldering without breaking the board.
    I played with a microphone like this:


    but I can't get it to trigger the interrupt correctly while the Arduino is sleeping. (Maybe an extra capacitor?).

    Any ideas?

  • That scheme is interesting, but I don't want to actually fiddle with the detector - for fear I will cause a malfunction. Hence my request of "without using power from the detector itself." Also, it would be nice to detect any kind of alarm (loud noise), not just a smoke detector.

  • how much volts is the smoke sensor powered?3v from 2 AA bateries?

    my bet for not drain bateries from smoke sensor itself its use a 3.3v arduino with wireless card(esp,nrf24 or rfm69,depends what you use on gateway) and make the alarm power the arduino itself. It means each time you get an smoke alarm ,the arduino is powered ,boot up and send an signal to gateway or what ever receive it. like this there are no power waste on arduino during months. you can use a transistor to power the arduino from smoke sensor bateries for exemple

  • @tmaster
    I appreciate the reply, but I really do not want to open up or modify the smoke alarm in any way - just detect a loud sound. As I said, I really just want a KY-038 that is suitable for battery operation.

  • New homes in the US now days are required to have smoke detectors that are linked together. This is so that if one goes off, the others will also go off. See this link https://home.howstuffworks.com/home-improvement/household-safety/question576.htm . If you had one of these detectors, you could probably feed off the signal interconnect wire.

  • with KY-038 will not work as you expect. Any loud noise,like something fall off will trigger the alarm. or other alarm fires and you thing its fire. i have one working on my visonic alarm for domoticz notify me, but its powered by mains power supply. I never used battery arduino for that because batteries just end in a few months and you think you are safe and you are not.

  • @tmaster
    Actually, the KY-038 works exactly what I want (except for the power consumption). I also have ones that are connect to mains power, and the false alarms are rare. Also, I have the Arduino programmed to sleep some time after detecting a sound and sending a message. In the case of a real alarm, it will keep sending regularly, which would make it obvious. The "batteries just end in a few months" is what I'm asking about - avoiding the .4ma used by the LM393. I'm hoping I can replace it with the LMV393, but I'm not sure if it will work.
    Regarding the "you think you are safe", Mysensors has heartbeats, and battery percentage reporting to deal with all that.

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