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well water level measure

Discussion in 'General Electronics Discussion' started by jbol, Jul 30, 2011.

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  1. jbol

    jbol

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    Jul 30, 2011
    I live in Texas where we are having worst drought on record - and our only source of water which is a shallow well is getting low. I would like to be able to monitor that level remotely since the well is 300' away. Looking for ideas.
    I currently have a 10 turn 500 ohm pot on a 1 foot circumference pulley that I can use with a float to generate a variable resistance depending on water level. There is a 3 wire power line going to the well - no ground. Running another wire is not practical.
    I am electronically savvy but out of date - think discrete component power amps. I also teach computing at local junior college so some kind of PC input (usb) would be interesting.
    Thanks ahead for any input
    jim
     
  2. daddles

    daddles

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    Jun 10, 2011
    The first question is "What are you going to do with the data once you have it?" Personally, I can't envision why you'd want to spend the effort, but let us know if there's a good reason.

    The obvious first thing to do is to contact the folks who dig and service wells to see if there's a commercial solution existing for what you want to do. I've never heard of one, but of course that doesn't mean they don't exist.

    The problem with a typical well is the pitless adapter, wires, and pipe that go down it. These can block line of sight.

    If you have a clear view of the static water level, then the first choice that comes to my mind is an ultrasonic radar. Next would be to develop something that drops a drop of water and listens for the return acoustic echo of the drop hitting the water. But such things would take a fair bit of engineering. When I need to know our water level, I stick a heavy nut on a string and lower it down the well until it hits the water, then measure the string.
     
  3. jbol

    jbol

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    Jul 30, 2011
    My concern is that the water level can drop to the level of the pump input where it will actually keep pumping water at a reduced rate - problem is that the pump then runs continuously which I don't want and the pressure is low. I can measure the depth manually as you say but the well is 300' down a steep hill (I didn't put it there) and I don't need that much exercise. The reason I want to know this is so I can go turn of any water sprinklers etc. and let the well refill.
    So I want to take the resistance reading on the pot and somehow transmit it (or some derived value) to the house.
    Thanks
    jim
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,477
    2,820
    Jan 21, 2010
    You can probably get by with just a simple sensor which tells you if the level is above or below a certain level. Knowing the actual level may be less important.

    If this is suitable, then there are a number of circuits which could work.

    Alternately you could detect how long the motor is running and raise an alarm if it runs continuously for more than a certain time.
     
  5. duke37

    duke37

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    Jan 9, 2011
    If the well is line of sight, you could use a semaphore system to give a visual indication. Alternatively, you could go to radio control. What range would a TV zapper have if given a large parabolic reflector each end?
     
  6. jbol

    jbol

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    Jul 30, 2011
    thanks for the responses so far - it is heavily wooded between me and the well so I guess I was looking for some kind of radio transmission - or - I recall circuits using isolation capacitors to send a signal back up the mains
    can anybody point me towards some good circuits?
    thanks
    jim
     
  7. daddles

    daddles

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    3
    Jun 10, 2011
    I still recommend that you contact some commercial places to see what options you have. At the very least, they may give you some ideas.

    I believe some pumps have switches in them to avoid running them dry. Of course, you won't know what you have if there's no documentation (like what happened to me when we moved into the house we're currently in). Then you're faced with pulling the pump out (easy for shallow wells, probably not quite as easy in the challenging terrain you're dealing with) to find out what you've got.

    Your well should also be on a pressure tank setup to avoid running the pump too much. One idea might be to start a timer when the pump comes on and shut the pump off if it runs too long. This works for normal use, but not if you're e.g. running sprinklers where the pump will run continuously. Then you ideally need some kind of flow sensor to know that the pump is really working correctly. This is going to run into $$.

    How deep is the well? What size is the casing? How big is the pitless adapter and the pipe going down into the well? Can you pull the pump yourself to install something?

    I believe the typical well pump has three wires going to the pump: the two 240 V lines and a ground line (I wired my pump and installed it about 10 years ago, but I can't remember the details now). So I'm envisioning pulling the pump out and installing a waterproof box with two sensors on it that detect the water's conductivity. If no conductivity is detected, the box puts some signal on the two 240 V lines which get detected at the house and acted on -- possibly an X10-type signal. This uses the existing wiring.

    Alas, this is both a challenging mechanical design (probably, to get things to fit in the bore) and some non-trivial electronics. I'd also worry about false positives through crud accumulating between the sensors -- you'd think there was water when there wasn't.

    Anyway, some ideas to think about.
     
  8. duke37

    duke37

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    Jan 9, 2011
    It is fairly easy to produce an audio frequency which varies according to the resistance of your potentiometer. If you can get one of the mains connected baby alarms, then a frequency to voltage convertor could give an indication of water depth. If you have three wires with no neutral then the voltage may be too high for a domestic unit without a transformer. I think that three phase/single phase connections are different in the US and UK.
     
  9. jbol

    jbol

    5
    0
    Jul 30, 2011
    It is a 28' deep shallow well in a 30" concrete casing so no problem measuring the depth. I am wanting to know the level so I can set the timer on the sprinkler without worrying about running out while I am gone. There is a pressure tank but if the water hits the pump's input level and there is still demand the pump can not create enough pressure to reach the turn off point.
    However, I had not thought about a mains connected baby alarm. That might be the solution since I already know haw to measure the depth.
    thanks again
    jin
     
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