• lemmefixdat4u@lemmy.world
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    1 day ago

    I always wondered why they say “front toward enemy” and not “this side toward enemy”. Because some idiot won’t know front from back.

    • Gimpydude@lemmynsfw.com
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      1 day ago

      Doorbells are powered. Either it’s a hardwired doorbell or there is a battery inside the button. That’s enough to set off a charge.

    • unexposedhazard
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      1 day ago

      Do they need one? I would have guessed that you just need to short the wires on a real one. But i have no knowledge so idk.

      • Bertuccio@lemmy.world
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        1 day ago

        A brief internet search says the signal in the real thing is mechanically generated by pressing the trigger on the hand unit, helpfully called the M57 firing device. So just shorting the wires without external power wouldn’t trigger it.

        That activates a blasting cap which is installed in the mine when it’s placed. I’m pretty sure it just needs one cap to work, but there are two places for them on top - the little upside down tophats where the wires end in the picture. So the one in the image might be wired wrong; both wires would need to go to the same cap on one side.

        I don’t know if a doorbell has enough juice to activate a blasting cap.

        • unexposedhazard
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          22 hours ago

          Seems much safer so yeah makes sense. There are doorbells with piezo electric systems so it might work if its the right voltage and if it isnt a complex modulated signal.