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Pressure plate style sensor

Discussion in 'Sensors and Actuators' started by Vicky982, May 25, 2017.

  1. Vicky982

    Vicky982

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    May 25, 2017
    Hello

    I am looking to make a new device and after some advice on the electronic component?

    I am in need of a sensor that will send a signal when a connection is broken. This will be a spring loaded connection, that when pressure is released the connection will break, it will then send a signal to a mobile phone, informing you to buy a replacement.

    Physical electronic components for this, does anyone have any pointers or advice on the best way to do this?

    Needs to be small and possibly lithium battery operated?

    Thanks
     
  2. shrtrnd

    shrtrnd

    3,672
    453
    Jan 15, 2010
    You didn't specify your application.
    Is this something that the pressure varies with until a final pressure release point is reached, or something that is mechanically static, and the pressure will only change when some release point is reached?
    If it's a physically static situation, I'd just bond a wire to the mechanism, that physically breaks when pressure on the plate is released (I would assume moving the plate physically, which would break the wire). The broken wire would
    break the electrical connection, and trip whatever circuit you decide to use which would activate your signaling device.
    if this is a more complex scenario (pressure variations while in use), it would help if you tell us the situation.
     
  3. Vicky982

    Vicky982

    5
    0
    May 25, 2017
    Hello,
    The pressure will only change when the release point is reached.
    Its for monitoring the levels of blocks of salt that will slowly be used from the bottom, once they shrink to a certain size, then will release the trigger and connect/break the circuit, triggering the signal being sent. Does that make sense?
    Thanks
     
  4. shrtrnd

    shrtrnd

    3,672
    453
    Jan 15, 2010
    Yes, it makes sense to me. Hopefully you'll get some suggestions from others here on signaling systems for your application. If I was looking at this project, I'd be asking the following questions about the trip-signal itself:
    1) Does the pressure plate actually move measurably when the salt blocks are gone?
    2) What sensing device (if any) monitors the pressure on the plate (load cell, or whatever), and if one is not there, should there be one. (That would not only tell me, if the signal from the load cell is monitored, not only when the salt blocks are gone, but when they would be about ready to disappear).
    3) If there is presently a simple switch that trips when the release point is reached, can I use that switch activation as a signal to my monitoring system. And if there isn't one, should there be one, like a simple lever-action trip switch.
    4) Do you have easy access to the holding container for the salt blocks, or access to the pressure plate itself if it's
    not an integral part of the salt block container itself.
    5) Will whatever senses the release pressure need to be manually reset or replaced each time. Or can something like a lever-activated switch under the pressure plate automatically reset itself.
    6) Is there salt dust or debris that can get under the pressure plate and inhibit pressure plate activation or deactivation.
    You probably already know the answers to the above questions, I'm just mentioning them in case it offers you any ideas about how to monitor pressure plate release. THEN, somebody will probably offer you some ideas about transmitting a signal to a cell phone to let you need the container needs attention.
     
  5. Vicky982

    Vicky982

    5
    0
    May 25, 2017
     
  6. shrtrnd

    shrtrnd

    3,672
    453
    Jan 15, 2010
    I'm mostly familiar with what's available in the States, but what you want for the trip signal when the pressure plate rises after the salt block is gone is called a 'limit switch'. US mfgrs would be places like Square D or Microswitch (many others). I'm sure there are dozens of European models available where you are. I'd Google 'limit switch', and check what's available to see what suits your purpose. (The size and lever length you need for your application).
    A limit switch works by a spring-loaded lever arm that connects to the switch. When the pressure plate rises, if set to the necessary distance, the lever rises with the pressure plate, activating the switch.
    You'd then use the switch contacts to activate whatever mobile phone monitoring device you decide upon.
    I'm not familiar with mobile phone activators, hopefully someone else here can help you out with that.
    A Google search with the right wording will probably assist you with that search also.
     
  7. Vicky982

    Vicky982

    5
    0
    May 25, 2017
    This sounds spot on for what we need. Thank you very very much.
     
  8. shrtrnd

    shrtrnd

    3,672
    453
    Jan 15, 2010
    Good luck with the success of your project.
    I don't know the radio/phone transmission laws where you're at, but since no one else has added information about your question concerning sending an alert signal to your mobile phone, I'll mention that there are systems here you can buy for home burglar alarms (for example).
    You're at work, someone trips a burglar alarm switch at your home, and the home base station notifies you on your mobile phone. So if you get stuck with that part of your application, you might check into something like an alarm system set-up.
    I'm assuming there are a lot of systems available to send you a mobile phone alert (everybody has mobile phones that do everything anymore), I'm just not involved with them to offer you any useful advice.
     
  9. Vicky982

    Vicky982

    5
    0
    May 25, 2017
    Thank you, I will look into this also. Will be speaking with app developers about this aspect also, as we are having our own app developed for this purpose.
    Thank you to everyone for your time and help
     
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