Door Chime Sequencer

Discussion in 'The Projects Forum' started by holabr, Apr 10, 2013.

  1. holabr

    Thread Starter New Member

    Feb 8, 2010
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    0
    I have a set of vintage door chimes that uses an electro-mechanical sequencer to activate a series of plungers to strike the chimes. The problem is the mechanism uses a low rpm motor to sweep a set of contacts over traces on a PC board to sequencially ring the chimes. It has worn to the point that it is no longer consistently rings the chimes. I've been testing the circuit with leds in place of optocouplers until I get the timing right (see attached). The problem I'm having to a shorten the activation of the led (about .2 second) while the time between each led in the sequence is about 1 second. Right now, each led stays on until the next one comes on. Is there some way to AND the output of the 555 with the outputs of the 4017 so the led is on only during the high pulse of the 555? I'd like to do i with discrete components that I have on hand rather that an IC if possible. Any ideas?
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Is there any chance you could use the existing low rpm motor and add a paper or cardboard disk with one hole near the perimeter. When the button is pushed, the motor rotates (as it does now), then the hole will pass by a series of phototransistors or LDRs to activate each bell.

    That way you can keep some "vintage" electromechanical aspects to it and the timing is still the same as your original.
     
  3. holabr

    Thread Starter New Member

    Feb 8, 2010
    14
    0
    I am actually going to keep the original mechanism intact and may remake the circuit board with the contacts in the future sometime. As a result, I do not want to change the basic design by drilling holes or otherwise modifying it. I am almost there with the replacement solid state controller, I just need a little help with the "AND" part to shorten the length of the pulse. Thanks for the suggestion.
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Yes, one quad 2-input AND gates will work. http://www.datasheetcatalog.org/datasheets/185/109330_DS.pdf

    Simply connect your 555 to your cd4017 as you did but add a branch from your 555 to one input on each of the four AND gate on the referenced chip.

    Then connect outputs Q0, Q1, Q2 and Q3 to the remaining input pins on the AND gate (respectively).

    Set your 555 timer to a 16% duty cycle to get 0.2 second on and 1.2 seconds total cycle.

    Finally, get rid of all the diodes and add one resistor for each LED. Then make a connection from pin Q4 on the cd4017 to its own reset pin. That way you don't have to wait for the whole 10 count.
     
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