Water Level Indicator

Discussion in 'The Projects Forum' started by aq_rules, Jun 6, 2013.

  1. aq_rules

    Thread Starter Member

    Oct 28, 2009
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    0
    Hello...

    I wanted an automatic control of my overhead tank...googled some schematics for it and found one, but i guess that it couldn't help with my 220v/ 2 horse power pump..
    [​IMG]

    please help me....if i need to change some components and which type of relay will be needed
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,036
    That looks pretty good - more elaborate (in a good way) than what I would have first thought of. You'll need a 12V DC supply for the circuit. The relay you need is one that can be triggered with 12V DC. I think I see in the drawing that it is a double pole one that is configured to latch on. And of course that relay must be rated to switch your (relatively large) load.

    What exactly are A, B and C? It's not a great idea to rely on water contact but it will probably last for a while at least. Pure water doesn't conduct, and probes are prone to scale and fouling. Float switches are more reliable.
     
  3. aq_rules

    Thread Starter Member

    Oct 28, 2009
    168
    0
    A B and C are the probes placed at different levels in the tank...D is the common probe..when D is in contact with A D1 glows, when D with B..D2 glows..
     
  4. LDC3

    Active Member

    Apr 27, 2013
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    In what order are A and B (since C just lights an LED, I am guessing that it is a full tank indicator).
    B will keep the relay latched. It looks like A unlatches the relay.
    Is this correct?
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,036
    I think I'd test the detection concept first with just the LEDs. The success of the entire project depends on the ability to pass a small current from D through the probe (and any scale and fouling on its surface) into the water, across the gap from D to A, B, or C, and then through the surface and into one of those probes. As I said before, you cannot assume the water will conduct unless it has sufficient impurities. But the very same impurities contribute to probe fouling.

    My gut says you can make this work if you don't mind making adjustments and refinements over time (moving the probes, trying different metals, etc.). If you need reliable operation right out of the box and for months on end afterwards, I'd be a little nervous.
     
  6. RichardO

    Well-Known Member

    May 4, 2013
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