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Simple DIY low water sensor

Discussion in 'Modding' started by Albinus, Jun 7, 2006.

  1. Albinus

    Albinus Member

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    Hi guys,

    Just got my greywater storage with a submersible pump set up, however the pump needs to be submerged at all times and thus a low water level alarm would be appropriate. I was thinking along the lines of when the water level drops, something goes open circuit, triggering an alarm. Has anyone got any easy, simple circuit diagrams that I'd be able to use? A closed circuit alarm would be easier (water completes the circuit) but an open circuit... how does one do that? :confused:
     
  2. Goth

    Goth Grumpy Member

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    You could use a float switch, or a sensor based on the conductivity of the fluid.

    A float switch doesn't really require any electronics at all, however if you want to use electrodes in the fluid to sense the level then perhaps a BJT or Opamp would be needed to give you a useful output.
     
  3. nux

    nux Member

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    You can buy those little floats that sit near the bottom of the tank. A lot can be wired up to either be a high water alarm or low water alarm.

    EG: http://www.jaycar.com.au/productVie...d2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

    Or you can get ones that are meant for a boats bilge. Should really matter if it goes Open Circuit or Closed Circuit when the water is low, a circuit can be easily adapted to use either.
     
  4. OP
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    Albinus

    Albinus Member

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    Thanks for the replies :)

    So if I was to get a float switch, and set it so that when the float drops the circuit is completed, simply hooking it up to a piezoelectric speaker would do the trick?
     
  5. nux

    nux Member

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    Yep exactly, that should work fine. Or you could make it light up a light if you dont want an annoying piezo speaker blaring at you :p

    You'd do it this way with the Jaycar one: "Mounting the switch so the float rises upwards when the fluid level rises above switch height it will switch OFF."
     
  6. Recharge

    Recharge Member

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    could also set it so the pump won't function when the switch activates, that way, the pump can't be damaged if you are away ;)
     
  7. OP
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    Albinus

    Albinus Member

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    Unfortunately it's a 240V pump, so water and electricity don't mix with my rudimentary soldering skills :p

    I'm fine with it, just that Mum will undoubtedly forget to check the water level and run the pump dry :upset:
     
  8. Recharge

    Recharge Member

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    lol, thats why you set up a relay system, though I'm pretty sure you get buy kits that do all this anyway.

    you could always consult your local plumber for advice.
     
  9. GriMo33

    GriMo33 Member

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    [​IMG]

    basically have two weight with some fishing line between them to stop the float going where ever it wants. have a piece of fishing line attached to a metal bar inside a piece of pvc pipe. the other end of said string attached to the float. have another metal plate with a hole drilled threw it above the plate attached to the float string.

    connect both plates to a wire. connect the bottom plate to the negative terminal on a battery (leave enough slack for it to move to the top plate). connect the upper plate to the negative terminal on a buzzer type object. connect the positive end of the buzzer to the positve on the battery.

    basically as the water level drops it lowers the level of the float. obviously u will have measured how long the fishing line needs to be so it sets the buzzer off at the right water level. when the float drops to a certain point it pulls the metal plates together, thus completing your circuit and setting the buzzer off. simply disconnect any of the wires to shut the buzzer up and do whatever needs to be done to get water level high, or turn the pump off.

    the drawing and explenation are rather primitive, as is my spelling, but its 5 a.m. so what can you expect. this does work in our water tank at home, but its above ground and im not sure how it goes with your set up.

    i used fishing line cuz its cheap and doesnt mind long times in water. bricks cuz they are non toxic cheap and weigh alot so wont move. floats are cheap as, or u could just use an old coke bottle. if it floats it will work. Dont skip the brick part or u will find your float buggers off to the far side of the tank and keeps giving u false alarms.

    its simple, cheap and u cand find most parts around ur house (except for the buzzer really).

    anyway ive done just about enough trying to explain myself, it kind of explains itself. feel free to use it, tell me its a shit idea, make thousands and sell them whatever. i dont really mind. its simple, works for me.

    ill come back tomorrow and fix spelling and check i have actually shown what i meant to show.
     
  10. nux

    nux Member

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  11. GriMo33

    GriMo33 Member

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    errrr, my tank has a hole in it to let water in anyway. And even though it would probably be more practical, buying a $20 float switch kind of defeats the whole Do It Yourself part of DIY
     
    Last edited: Jun 9, 2006
  12. billb

    billb Member

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    Have a look at this. http://www.overclockers.com/tips1114/
     
  13. newSpeak

    newSpeak Member

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    That reminds me of an "incredible machine" competition i did in highschool where you got marks for making it as wacky as possible.

    I recommend an electronic solution. I had a browse around on the commlinx project page for a suggestion. Here is an idea on how to do it:
    http://www.mitedu.freeserve.co.uk/Circuits/Alarm/water_lev_alm.htm

    The page explains how the design works and i think it is a good starting point if you want to design your own solution. I would recommend replacing the transformer and bridge with a 9v dc plugpack. The logic gates require 5v so use a suitable voltage regulator. It also might be a good idea to use a fuse in your design.

    Disclaimer: This isn't my design and i don't know if it works off the page. It's just an idea :)
     
    Last edited: Jun 12, 2006
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    Albinus

    Albinus Member

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    Thanks again guys :)

    One of my mates is a sparky and is modifying the pump with a flow sensor so that when the sensor has less than the determined amount of water flowing through it, it will trip the AC connection. To start the pump I'll just need to have a shorting override for the first few seconds :)

    Forgot he still played around at the small end of town :p
     
  15. billb

    billb Member

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    Uh Hu, and what happens when a power glitch reboots your PC.....and it restarts without the pump running...or is sparkey addressing this? And anyway all modern CPUs have overtemperature shutdown...so what's the point?

    If you can run motherboard monitor it can call (at a user determined temp) a program called Shutdown Now that can shut down, hybernate, or a whole hyriad of other stuff and it's all done with software, no physical components to fail.
     
  16. nux

    nux Member

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    Erm wtf? What has a computer got to do with it, he isnt watercooling..
     
  17. billb

    billb Member

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    Eh! Sorry, where I come from we don't use graywater!
     

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