need to convert steady state stop info to pulse on organ

Discussion in 'The Projects Forum' started by hsmoller, Jun 11, 2014.

  1. hsmoller

    Thread Starter New Member

    Jun 11, 2014
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    Hi
    I need to convert "stop on, stop off info" to pulse info.

    We are trying to convert stop info which is 12v+ when the knob is pulled to 12v off when knob is pushed to an output which receives a pulse to turn a device on and another pulse to turn the device off. The device actually has switch points similar to a lamp switch (i.e. to turn on "flute" touch terminal 9 to 33, etc)
    Thanks
    Harv
     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    From a black box point of view:

    The input is a 12V signal wire and GND. The input wire goes from GND to +12 when a stop is pulled, sits at +12 V as long as the stop is out, then drops to GND when the stop is pushed in.

    The output is a single output wire and GND. The output makes a pulse that is x1 volts tall and x2 milliseconds long when the input goes from GND to +12V, and the same output wire makes another identical pulse when the input goes from +12V to GND.

    Correct? What are the values for x1 and x2?

    ak
     
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  3. hsmoller

    Thread Starter New Member

    Jun 11, 2014
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    The stop switch is like an spst switch which
    Activates a stop input board. The volts is
    Frim 12v stop on to 0v stop off. The device
    We want to control is first pulse on 2nd
    Pulse off. I think the output of this conversion
    Circuit should have enough volts to drive
    A relay. I have this clarifies the situation
    Thanks
    Harv
     
  4. hsmoller

    Thread Starter New Member

    Jun 11, 2014
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    0
    PS the amplitude of the output pulse again should be enough to drive a low voltage relay (the voltage unimportant) and the pulse width around 200ms but not critical. I would think there needs to be a debounce circuit with the stop switch (which is pull on, push off magnetically controlling a reed switch)
    Harv
     
  5. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    OK, a reed switch connected to a 12 V source is the input, and you want to close a relay on both the leading and trailing edges of the input, so go with a 12 V relay coil. What is the load the relay is controlling - AC, DC, voltage, current? This sets the size of the relay, which sets the size of the relay coil, which sets the kind of relay driver circuit.

    I think 200 ms is bit short for a relay coil pulse; 500 ms would be better. Also, reed switches have very little bounce so the length of the relay coil drive pulse will cover debouncing.

    ak
     
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  6. ScottWang

    Moderator

    Aug 23, 2012
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    767
    If you could draw a block diagram to show how the signal going, it is more clear, I just thinking maybe you can use CD4013 to do, but it's need some detail infos.
     
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  7. hsmoller

    Thread Starter New Member

    Jun 11, 2014
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    Upon looking at the stop switch we noticed there is a provision to mount the reed switch mid travel, and there are separate terminals on the pc board provided for it. This would enable the sliding stop switch to produce a pulse while travelling outwards and another pulse by travelling inwards. i think a capacitor across the reed switch will minimize any bounce. Our problem at the other end at the sound module box is the terminals are not consistent to a common, so they would have to be treated as isolated switches. So this arrangement would be fine. The only caveat is if the organist leaves the stop knob in the on position. When the organ would be powered up again, the stop would wok backwards--so a sign will be mounted to always press the "general cancel" before the organ is shut off. Thanks again for your input. We will still try the components and circuits suggested in future applications.
    Harv
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    1,105
    I don't see why you need a relay (other than the reed relay). If you know the input pulse requirements of the audio module why can't the 'black box' drive the module directly?

    How does the module recognise the 'general cancel' command? What form does this command have?
     
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