water level detector.

Discussion in 'General Electronics Chat' started by vivek.raunak, Jan 24, 2011.

  1. vivek.raunak

    Thread Starter New Member

    Oct 23, 2010
    29
    0
    hiiiii

    i am doing project on water level detector.......
    i need some modification.......
    can u suggest some?
    i have attached my circuit diagram here....
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,638
    2,344
    Hello,

    What kind of modifications are you thinking of?

    Bertus
     
  3. vivek.raunak

    Thread Starter New Member

    Oct 23, 2010
    29
    0
    hi,
    i want to control water level of the tank automatically,
    mean if water would fall below an specified level motor should switch on automatically.......
    and in the same way if water starts overflowing motor should switch off.
    plz suggest me an idea....
     
  4. JDT

    Well-Known Member

    Feb 12, 2009
    658
    85
    You need a latching circuit. Also known as a SR latch. Two NAND gates cross-coupled are a classic implementation of this. Half of the familiar "4013" can also be used (tie the D and clk inputs to 0V). Use logic on each input to the latch so that it will be set when the water level gets below a certain point and reset when it gets up to another point.

    Control your pump via a relay so that it is isolated from your level detector circuit.

    Your level detector circuit will work but suffers from a problem that only DC is used on the probes. In time there will be electrolytic action that can cause corrosion. Better detectors (all commercial types) use AC.
     
  5. bertus

    Administrator

    Apr 5, 2008
    15,638
    2,344
    Hello,

    You could feed the outputs of the desired and ports to a flip-flop.
    The flip-flop cab control the motor over a power stage.

    Bertus
     
  6. vivek.raunak

    Thread Starter New Member

    Oct 23, 2010
    29
    0
    hello sir,
    very very thanks for your precious suggestion .........

    u mean to say corrosion takes place inside the tank...........
    but what if i use an inverter ?
    it will convert DC signal into AC.

    how the commercial level detector is made?
     
  7. kcarring

    Member

    Jan 22, 2011
    38
    0
    You might want to look around for a more corrosion resistant style well nut. The typical RV water storage tank well nut doesn't hold up for more than about a year. As an RV technician, I am all too familiar with this. The circuits on RV have a resistor block, and the panel detects the different levels based on resistance. Unfortunately, the meters start to lie, sooner than acceptable, usually based on the well nuts failing to do their job properply, as mentioned earlier: corrosion.

    It may be that stainless hold up better. I do know kayaks have some. Research and see if a better well nut is available. (If that's what your using)

    http://topkayaker.net/topkayakersho...ducts_id=142&zenid=008dn80jv4iea99q104fgs62d0
     
    Last edited: Jan 26, 2011
  8. vivek.raunak

    Thread Starter New Member

    Oct 23, 2010
    29
    0
    sir,
    is it possible to design it with combinational circut.
    we already designed it by using SR latch...
     
  9. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You might find something like the attached circuit more useful and easier to build.

    C1 is a pair of conductive plates with a surface area of 12 square inches, or roughly 30 square centimeters space 0.1" or 2.54mm apart. It could be any shape; circular, a long strip, rectangular - just as long as the surface area and spacing are approximately those dimensions. The plates could be single-sided raw PCB stock. They can be conformal coated so the water cannot contact the copper surface.

    With no water between the plates, the output will be a logic low. As more water comes between the plates, the output starts to generate pulses. When the plates are completely covered with water, you will see a square wave output.

    This is an inexpensive and simple circuit to build.
     
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