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Water level meter

Discussion in 'Sensors and Actuators' started by HyOxy7, Feb 11, 2020.

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  1. HyOxy7

    HyOxy7

    3
    0
    Feb 11, 2020
    Hi,
    I´ve been searching for a 12V water level meter for my HHO generator but I´m having some trouble finding the right meter.
    The 5L plastic reservoir contains distilled water with potassium hydroxide as the electrolyte.

    I need a sensor to detect Low water level, preferably a non-contact type like this guy:
    https://www.ebay.com/itm/5-12V-Non-...hash=item1f0b149ab5:m:mZMLQ22VaddyZgdT6xoWVzA

    You´ll find plenty of these on ebay, but from what I´ve read they only get triggered if they detect water, not the other way around.

    In my application, I would need a sensor closer to the bottom of the tank to make the buzzer go off when the water level drops below it.

    Thanks
     
  2. Bluejets

    Bluejets

    3,690
    761
    Oct 5, 2014
    It's an npn output and one can use it whichever way around one desires.
    AS the instructions in the link you provide near the circuit diagram explains.

    If you connect a relay, for example, to this output with change over contacts , you can drive whatever.
     
  3. HyOxy7

    HyOxy7

    3
    0
    Feb 11, 2020
    You´re right, it´s just a matter of connecting the black wire to the blue wire to reverse it. Thanks man!
     
  4. Bluejets

    Bluejets

    3,690
    761
    Oct 5, 2014
    Just be aware that output has a maximum handling current of 200mA and whatever you intend to drive with the sensor may draw more current than that.
    In which case a relay or similar would be required.
     
  5. HyOxy7

    HyOxy7

    3
    0
    Feb 11, 2020
    I´ll be using a small piezo buzzer in my generator, it shouldn´t pull more than that.
    I´m thinking about putting one in my car´s water tank since I had so many leaks already. Is it ok to drive it off the battery directly?
     
  6. Bluejets

    Bluejets

    3,690
    761
    Oct 5, 2014
    Piezo will be ok.
    As for the rest, the link shows a few different types of sensor.
    Some are 5 to 12v and others 5 to 24v so depends which unit you have as to use in your vehicle.
    Most 12v cars will go at least to 13.8v on charge so it depends on the unit as to whether or not it will survive.

    If your car has system leaks, then putting any device on the reserve tank would be pretty useless.
    It may dump excess water in there during heat-up period, but when required, the system has to suck the water back.
    If you have leaks, there'd be little vacuum.
    You'd have no excess water to pump into there anyhow.
    Most radiator detectors are a probe in the main tank top section so any loss is immediately obvious.

    I used to make them here. A 555 and probe in the tank with an audible alarm in the dash.
    Problem with most probe designs is the dc to the probe creates electrolysis that rots the probe and gives abnormal readings. Got around that by feeding a sort of 555 generated ac pulse just to the probe circuit.
    All my drawings went in the 2013 flood though so no longer here........more likely than not there would be many similar circuits out there.
    Then of course there are the newer type capacitive probes, all invasive though with metal radiator.
     
    Last edited: Feb 14, 2020
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