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Water Detector Circuit W/Relay

Discussion in 'General Electronics Discussion' started by brodie4416, May 17, 2013.

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  1. brodie4416

    brodie4416

    1
    0
    May 17, 2013
    Hello, if you wouldn't mind, I have been working on this circuit for a week and it still is not working!!

    I am trying to detect water by running 12V through a wire, if there's water, the "switch" (it is basically an open wire with the leads about half an inch apart) will be closed, if no water, the "switch" will be open. I am then using that 12V to attempt to trigger a 5V (or 12V, either doesn't work) relay to then activate a water pump (takes 24V) whenever there isn't water. The "switch" appears to be working but I think I lose too much current through it.


    https://www.circuitlab.com/circuit/5jxz68/waterdetector/


    The issue is that I don't think I'm getting enough current through the relay because even though I can measure over 5V at both ends of the relay coil with respect to ground, the relay does not activate! If I remove the resistor R1, the voltage drops to less than 1V... HELP! Thanks
     
  2. shrtrnd

    shrtrnd

    3,822
    519
    Jan 15, 2010
    I don't know if this is a school project that has to be done a specific way or not.
    First, conductivity of water is better with the more impurities there are in it. The cleaner
    the water, the less conductive it is. Maybe your circuit will work better if you move
    your 'water' contacts closer together.
    What perked my interest in your post, is the fact that I've built a lot of water-detectors
    using a CD4011 & CD4001 integrated circuit chips, that are simpler to use. I've used
    them primarily to detect the presence of water in places where there shouldn't be any.
    If you have to make your circuit work, hopefully somebody can see something in your
    circuit that might need to be re-worked to get it right.
    I, myself, would Google some of those simpler CMOS water-detection circuits.
    Good luck.
     
  3. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    652
    May 8, 2012
    Your circuit can't possibly work as shown. The switch contacts that you show (that is actually a water conductivity path) is not wired where it should be. It must be from the + supply to the Base. The Beta of the NPN is also a factor. What's the pull-in current of the relay?

    Chris

    Note!! Your protection Diode is backward too!!
     
    Last edited: May 17, 2013
  4. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    You have apparently changed your diagram twice from when you first posted. You should not do this, as anyone coming back to the thread will be confused (at least I was). If you make a change, post it as a new circuit and link to it in the a new post, and tell us what you have done.

    You have apparently fixed the connection to the base as Chris suggested, but the not polarity of the flyback diode.

    Also, it would help if you would draw the schematic in the standard way, with ground at the bottom and V+ at the top. My head is getting sore from standing on it to read your schematic.

    Bob
     
  5. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    652
    May 8, 2012
    Sometimes I post a schematic and spot an error or maybe a note that I failed to include on the schematic. In those cases I hustle by butt to remove, amend, append and re-attach the schematic within about a minute or two of my original post. Sometimes I even beat EP's 'Edited' tag. However, once someone has commented on a schematic it should be verboten to edit it for the reasons that Bob pointed out.

    Suggestion to the Mods:
    Perhaps what is needed is a script solution that would prevent image editing, removal immediately upon the posting of any new reply. Do we have a switch for this??:)

    Chris
     
  6. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Except that this schematic was linked to and probably changed at the linked site.

    Bob
     
  7. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    652
    May 8, 2012
    That's problematic Bob. I don't see any way of controlling that. :(

    Ideas?

    Chris
     
  8. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Yes, virtual caning for anyone who does not comply.

    Bob
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
    2,838
    Jan 21, 2010
    Virtual caning applied. :D

    (I have let brodie4416 know that by changing the schematic in his link he has inadvertently changes the focus of this thread from assisting him to a discussion of his posting techniques).

    I have also done it using a method I've not used before (essentially the issuing of a "yellow card").
     
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