Latching relay with photocells.

Discussion in 'The Projects Forum' started by nicoyenny, Jan 19, 2009.

  1. nicoyenny

    Thread Starter New Member

    Jan 19, 2009
    3
    0
    Hi everyone:
    I have to setup a timing system where:
    - A piston moves inside a cylinder, measuring volume, I have all that setup already, need help with the electronics.
    - A photocell will detect the piston moving at certain point and should be able to start a timer.
    - A second photocell will detect the raising cylinder and stop the timer. At this moment, the cylinder will lower, but the timer should not reset or start over, but instead it should keep the time measured for the technician to record it.

    We have some aromat sensors, they can be setup for NPN or PNP (NO/NC), they work with 12-24 VDC, and we can make them work, no problem.

    I need some ideas, help with the timer controlling circuit. Our timers start with a NO switch, and they keep counting as long as the contact in the switch is closed, as soon as the contact opens, they do stop the timing.

    Thanks.
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    The piston will go up and then go down and stay down? Or it will moving continuously up and down?
     
  3. nicoyenny

    Thread Starter New Member

    Jan 19, 2009
    3
    0
    The piston will go up, and then it will go down to its zero volume position.
    It should not activate the relays when coming down, the timer will reset and start counting again when the piston rises again for a new cycle.
     
  4. mik3

    Senior Member

    Feb 4, 2008
    4,846
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    Is there another input on the timer to reset it?

    Can you tell where the datasheets of the sensors and timer are on the internet (if available).
     
  5. italo

    New Member

    Nov 20, 2005
    205
    1
    I don't think a photocell will work unless there is a light source to interupt. Well asue that is there then all you need a clock and a counter. One trigger the start the other stop the counter. How can you read the count well you will need a 7448 led driver to read it or lcd. the faster the clock the more acurate time wise.
     
  6. nicoyenny

    Thread Starter New Member

    Jan 19, 2009
    3
    0
    http://www.newark.com/pdfs/datasheets/Panasonic/MQ-W.pdf <-- Those are the sensors, they can be setup NO or NC, that's easy.

    The timers we have, have 2 contacts. If the contacts are closed, the timer starts counting, and will count as long as the contacts keep closed. When the contacts are open, the timer will stop counting for the operator to record the info.
    If the contacts are closed again, it resets and starts counting again from zero...

    The relays I am using are these:
    http://www.onlinecomponents.com/productfiles/mf-AR/mech_eng_jw.pdf

    The ones under "2 form C"

    Thanks!
     
  7. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Can you build a circuit with logic gates if I draw it for you?
     
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