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Water level indicator issues

Discussion in 'General Electronics Discussion' started by Daim, Jun 19, 2017.

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  1. Daim


    Jun 19, 2017
    The circuit uses the widely available CD4066 biteral switch CMOS IC to indicate the water level through leds.
    What this circuit should be doing is that, when the water is empty to wires in the tank are open circuited and the 180k resistors pulls the switch low hence opening the switch and LED's are off. As the water starts filling up first wire in the tank connected to S1 and the + supply are sharted by the water. This closes switch S1 and turn the led 1 ON. As the water continues to fill the tank, the led 2, 3 and light up gradually.
    When the water is full the base of the transistor BC148 is pulled high by the water and it saturates the transistor, turning the buzzer ON. The SPST switch has to be opened to turn the buzzer off.
    I have connected everything properly and used all the correct compenents for the circuit but apparently the circuit is not working.

    Attached Files:

  2. KMoffett


    Jan 21, 2009

    How is it "not working"?

  3. Alec_t


    Jul 7, 2015
    The top part of the circuit is missing. No wonder it doesn't work :).
    davenn likes this.
  4. Bluejets


    Oct 5, 2014,....... shouldn't there be a ground connection to the tank?
    mmm...on second thoughts, maybe not BUT the probe on the left is touching the tank bottom so is this correct?
    Maybe just need to recheck your connections as mistakes can easily be made like for example with the "compenents and biteral" amongst others.

    Found a full diagram and a link.

    Attached Files:

    • 6.gif
      File size:
      9.3 KB
    Last edited: Jun 19, 2017
  5. davenn

    davenn Moderator

    Sep 5, 2009
    there should be or if the tank is plastic there should be a ground ( circuit return) probe at the lowest level in the tank

    naaaa, just poor drawing .... that is the 1/4 tank level marker probe
    Last edited: Jun 20, 2017
    Bluejets likes this.
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