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  • Apr 23, 2007, 07:27 PM
    Diodes in a door bell
    Would you tell me what is the purpose of a diode in a door bell push botton?
  • Apr 24, 2007, 08:06 AM
    I am no expert on this, but I can guess...

    The doorbell is powered by an AC transformer, but the bell wants to be driven by DC. I think the bell typically consists of a spring-loaded plunger that's operated by an electro-magnet, so that the plunger strikes the bell when you push the door bell button. The electromagnet wouldn't operate properly on AC current, as that would cause it to vibrate at 60 Hz, rather than just move in one direction when you press the button. The diode allows current flow in only one direction, hence it takes the AC current and cuts out the half of the wave that's the wrong polarity. Anyway, that's my guess. I would actually think that the bell manufacturer would have built the diode into the bell housing or transformer, not the button - perhaps it's a redundant "belt and suspenders" approach?

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