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Re: [Electronics_101] Re: pressure/vacuum switches

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  • Stefan Trethan
    problem solved - i hope. i put a spring inside the water level sensor, well, it will now act as a vacuum switch but the pressure is way too low, one would need
    Message 1 of 13 , Apr 3 1:51 AM
      problem solved - i hope.

      i put a spring inside the water level sensor, well, it will now act as a
      vacuum switch but the pressure is way too low, one would need a very, very
      strong spring (maybe 20kg / 200N force). This doesn't work.

      So the membrane is too large.

      Then i thought of the solution: a thermostat.
      A thermostat like in a fridge or freezer or heater of some sort is only a
      metal bellow and a tube in which a gas is expanding due to heat. So i took
      a old one and opened the tube end, and found it will react to 1 to 2
      positive athmospheres of pressure depending where the control knob is set.
      I'm positive this is fairly easy to modify it slightly so it will react at
      a slightly lower pressure, and i will put it in some kind of container and
      seal the wiring so it works with vacuum instead of pressure.


      Seems like i found a $0 solution after all - tried for the analog pressure
      sensors at ebay but they ended up too expensive.

      ST
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