Water sensor/power shutoff *urgent help needed*

Discussion in 'The Projects Forum' started by kyroguy, Feb 18, 2011.

  1. erich_7719

    Active Member

    Oct 14, 2009
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    You will have to drill and tap them but yes they may work, and yes $40 + sensor and S/H (shipping/handling)
     
  2. erich_7719

    Active Member

    Oct 14, 2009
    92
    7
    Just out of curiosity; have you considered how your going to house this project or what your going to build it on?
     
  3. kyroguy

    Thread Starter Member

    May 12, 2010
    77
    0
    I ordered the stuff from mouser.

    As far as mounting and housing it I will breadboard it first to make sure everything is working properly. Then I will move it to a small pcb. I have a bunch of small project boards around that should work. I will choose an enclosure once I have a chance to size everything up. Did you have any specific suggestions here?

    Now I have to take another look at that sensor and get it ordered.
     
  4. kyroguy

    Thread Starter Member

    May 12, 2010
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  5. erich_7719

    Active Member

    Oct 14, 2009
    92
    7
    In the means of what I had in mind. I had a PCB made for mine and is mounted in a single gange electrical box mounted to the wall behind my tank.

    The lead time is worse case I believe I got mine in about a week.

    The ebay item I would ask a few questions;
    1st. Why is the bid starting at $14 when the manufacturers web site has the same part fo $95 (http://www.dwyer-inst.com/Products/Product.cfm?Group_ID=16&sPageName=Ordering).
    2nd. Neither the manufacture or ebay state weather the output is high in air or in water. If it is high in water than the design will have to be modified.

    The choice is yours.

    [side note]
    here is what I was thinking for the final board, the SSR would be mounted elsewhere's.
    [​IMG]
     
  6. erich_7719

    Active Member

    Oct 14, 2009
    92
    7
    Also the project boards will work as well.
     
  7. kyroguy

    Thread Starter Member

    May 12, 2010
    77
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    That PCB is pro! What does something like that cost and how long does it take to get done?

    I will call the manufacturer on the sensor tomorrow and check the lead time. I don't want to take a chance so I think I will stick with your suggestions and go with the one you linked to. I hope this anemone doesn't have babies again!
     
  8. erich_7719

    Active Member

    Oct 14, 2009
    92
    7
    I use batch PCB it is about a month for final product $10 setup fee and $13.30 for the board (so $23.30 would get you 2 boards). the link to the board if you want it is here.

    That board is designed to fit nicely into this, and this cover drills nicely for the switch.
     
    Last edited: Feb 20, 2011
  9. kyroguy

    Thread Starter Member

    May 12, 2010
    77
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    I think I am going to hold off on the board. It would definitely make the project look nicer but I really don't want to wait a month for it. Also the added cost is a consideration. I have had good luck in the past just using the generic project boards.

    For future reference how do you make the custom PCB? Is there a program that you can enter a schematic and then it spits out the design? I love the look I just don't have the know how.
     
  10. PatM

    Active Member

    Dec 31, 2010
    81
    72
    Not a very elegant solution, but effective.

    N.O micro-switch, resting on a aspirin tablet, holding a relay activated to power the pump.

    When the aspirin gets wet, the switch opens the relay cutting power.
     
  11. erich_7719

    Active Member

    Oct 14, 2009
    92
    7
    I use Eagle. It takes some getting use to but it works. The home page is here if you want to check into it. Also I attached the Eagle files for this project if you want to check them out as well.
     
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  12. kyroguy

    Thread Starter Member

    May 12, 2010
    77
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    Pam, that is an interesting idea. I just have a feeling by the time the aspirin dissolved there would be water on my floor...again. I need an instant solution. :)
     
  13. DustinGebhardt

    New Member

    Feb 21, 2011
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  14. kyroguy

    Thread Starter Member

    May 12, 2010
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    Dustin, what is the cost like on those? I am unlikely to use them for this project since I have already ordered other parts but I am always looking for inspiration for future projects!
     
  15. DustinGebhardt

    New Member

    Feb 21, 2011
    6
    0
    I think these units sell for $150 or so. However, I think the group could work out a DIY solution. As I understand their function, the 2 metal rods have a very small AC potential across them. When both are immersed in a conductive solution, current flows, triggering some internal logic, relay, etc. These work well for precision level control because you can make the leads different lengths. This allows you to (for a high-level alarm) to set the longer leg into the water and adjust the shorter leg to the exact cutoff point that you want. They make these units with leads up to 48" long (in stock models) and they can custom make units with leads however long you need.

    They make a 3 legged model, which is the one I use at work most often. I can set 1 leg to be very long and 1 leg to be slightly shorter. This serves as a low-level alarm. Then I set the last leg to be very short, giving me a high-level alarm. It is very simple and more elegant than float switches.
     
  16. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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  17. kyroguy

    Thread Starter Member

    May 12, 2010
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    I'm pretty committed to the design that has been laid out at this point. I was originally thinking about going the way you mentioned, Ken, but I couldn't find a simple circuit. I was also worried about probe corrosion. I understand that AC current prevents corrosion due to (what I understand to be) electroplating, but I am worried due to the fact that they will be in very close proximity to salt water. The salt water obviously corrodes stuff badly, electrical or not. The IR sensor is sealed tight and the rest of the circuit can be safely away from the water.

    I appreciate everyones input for this. Keep those suggestions coming!
     
  18. DustinGebhardt

    New Member

    Feb 21, 2011
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    Kyroguy,
    I'm an electroplating chemist, and while I normally work in the DC world, I've never had any of my purchased sensors fail due to corrosion. Then again, my probes are either stainless steel or titanium . . . ;-)
     
  19. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    To add to Dustin's post, I used ER316L stainless steel TIG welder filler rod for my electrodes. 316 has "excellect" corrosion resistance and is used in saltwater environments.

    Then again, if you have sealed sensors, all the better.

    Ken
     
  20. kyroguy

    Thread Starter Member

    May 12, 2010
    77
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    Got the parts from mouser today. Quick question, what are the "terminal blocks" for?
     
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