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HELP: Issue with Powering a Door bell on a Relay

Discussion in 'Electronic Basics' started by Ariel Suero, Jun 25, 2013.

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  1. Ariel Suero

    Ariel Suero Guest


    So I have put together the following circuit found in the link and everything with the regular part of the circuit namely, lights, switches, lock-out function all work.

    I have wired up a common house-hold door bell which comes with it's own transformer to step down the voltage. And, I'm supplying power via it's own ACcord wired within a project both separate from the Game Show circuit. I'm using the small relay circuit to act as the door bell button.

    Problem is it seems as though the capacitor maybe too large and is not discharging fast enough.

    What I'm seeing after I press one of the game show switches is the corresponding light coming on, but with a slight delay the bell rings. However I'venoticed a hum coming from the bell unit when powered and connected to the relay circuit. It appears that piece that hits the bell plate is holding and then heating up when plugged in for a bit of time.

    Can going from a 1000 uF capacitor to perhaps a 500 or 250uF help solve thedelay, the sticking of the bell striker? Any help would be greatly appreciated, I'm sooo close to finishing and this is the only detail holding me up..


  2. ehsjr

    ehsjr Guest

    Your circuit is working as designed. The doorbell striker will
    move to the "bing" side when a contestant's bulb lights, and
    will stay there until the reset switch is pressed. The 1000 uF
    cap and 51 ohm resistor will hold it there for about one more
    second _after_ the reset switch is pressed. Reducing the value
    of the cap will shorten that one second interval, but will have
    no effect on the time between the bulb lighting and the reset
    switch interval. If a contestant's bulb lights and no one
    presses the reset switch, the doorbell striker will remain
    on the "bing" side forever - or until something burns out or
    power is removed.

    If you want continuous ringing as long as a bulb is lit, change
    to a different type bell, like this: (Watch for line wrap in the url above)

  3. Ariel Suero

    Ariel Suero Guest

    Hello Dan, I will check the wiring of the relay today. I'm presently using 25 Watt colored incandescent bulbs I purchased from home depot and have them attached via a basic bulb socket.
  4. Ariel Suero

    Ariel Suero Guest


    Thanks to all who offered their valuable advice and knowledge. The project is complete and working great!!! I found that the door bell was wired to the NC instead of NO, I misinterpreted the layout on the back of the baggie. Also, I found that there was a bad diode in relay portion of the circuit. Replaced the diode, and connected to the NO, no need to step down the size of the capacitor.

    Thanks Again!!

  5. Jamie

    Jamie Guest

    I can't help felling that some of us are being quizzed.

    Why did you put a cap in series to the relay coil?
    I mean, I suppose you can do that but you're going to
    get AC to the relay coil and I'd wager that it's a DC coil

  6. Jamie

    Jamie Guest

    No, I didn't miss the rectifier, but obviously you missed something..

    The 100 Uf cap that is being used on the HV side of the scr's isn't
    enough to supply a clean DC to cathode side where the
    1000uf cap is being used to pass the momentary pulse to the relay.

    Instead, you'll most likely get a little noise there after the
    initial pulse. Any of the 25 watt lamps are on at the same time which
    on serves to add to the over over burden 100uf.

    Now maybe if the DC coil current requirements were a little higher to
    prevent it from partial latching after initial pulse, it could work.

    You see, I look at circuits like that, I can see holes a mile away..

    Have a good day..

  7. ehsjr

    ehsjr Guest

    Disregard my post above - I had the wrong circuit
    in mind.

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