Project : Pet Water Dish Alarm Sensor

Discussion in 'The Completed Projects Collection' started by Wendy, Nov 25, 2015.

  1. Wendy

    Thread Starter Moderator

    Mar 24, 2008
    20,766
    2,536
    I revised this project. Here are the changes.

    Pet Water Sensor v2.png

    I don't think I've ever used so much super glue so many ways to build a project before. I glued the parts to the back of the Sonalert and point to point wired it with small pieces of wire. I then super glued the Sonalert to the box, lining up a hole in the box I drilled with the hold in the Sonalert. I glued the LED and wires in their respective holes to keep them from wiggling.

    1.jpg

    Parts List
    2 Leads - one red, one black, with alligator leads already attached.
    Medium Project Box
    AAx2 Battery Holder w/ Batteries
    Small NO Push Button
    Sonalert
    IC - 7555 CMOS
    Q1 - 2N2222A
    Q2 - PN2907A
    C1,2 - 470μF 6.3VDC Electrolytic
    R1,3 - 1MΩ
    R2 - 1.5KΩ
    R4 - 10MΩ
    R5 - 470Ω

    It works as predicted, I used picture hanger wire for the electrodes and clipped to the wires. The wire I used for the probes was fairly rusty after 5 months of use, but was still functional.

    When the pet water dish is empty it will sound the sonalert for 1/2 seconds every 6 minutes. The idea is to be a gentle reminder, not scare the pets. I have repurposed the LED as a battery test, as I needed that function and the sound was what I am keying from after using it for several months. The LED only draws 1ma when lit.

    2.jpg

    I used a combination of Dead Bug Prototyping and Manhattan Style Prototyping. I used the description on pages 9-11 of the Manhattan Style document to make the circular pads for the sensor contacts.

    5.jpg

    I used Velcro to attach the finished box to the top of the water jug as shown.

    6.jpg

    The pictures are from my new smart phone. I can get used to these features, but still have some learning to perform on it.
     
    • 3.jpg
      3.jpg
      File size:
      312.5 KB
      Views:
      4
    • 4.jpg
      4.jpg
      File size:
      325.4 KB
      Views:
      5
    Last edited: Mar 17, 2016
    RRITESH KAKKAR likes this.
  2. Wendy

    Thread Starter Moderator

    Mar 24, 2008
    20,766
    2,536
    This is the project before I revised it, kept for archive purposes.

    I finished the project I described here.

    [​IMG]

    I don't think I've ever used so much super glue so many ways to build a project before. I glued the parts to the back of the Sonalert and point to point wired it with small pieces of wire. I then super glued the Sonalert to the box, lining up a hole in the box I drilled with the hold in the Sonalert. I glued the LED and wires in their respective holes to keep them from wiggling.

    There is no on/off switch, I place current draw under 10μA. If I get energetic I may add a simple push button / LED circuit as a battery tester later, it is hard to tell what the state of the batteries are otherwise.

    Parts List
    2 Leads - one red, one black, with alligator leads already attached.
    Medium Project Box
    AAx2 Battery Holder w/ Batteries
    Sonalert
    IC - 7555 CMOS
    Q1 - 2N2222A
    Q2 - PN2907A
    C1,2 - 470μF 6.3VDC Electrolytic
    R1,3 - 1MΩ
    R2 - 1.5KΩ
    R4 - 10MΩ
    R5 - 10Ω

    100_4144.JPG

    100_4150.JPG

    100_4152.JPG

    It works as predicted, I used picture hanger wire for the electrodes and clipped to the wires.

    When the pet water dish is empty it will flash the LED and sound the sonalert for 1/2 seconds every 6 minutes. The idea is to be a gentle reminder, not scare the pets.

    I used a combination of Dead Bug Prototyping and Manhattan Style Prototyping. I used the description on pages 9-11 of the Manhattan Style document to make the circular pads for the sensor contacts.

    I used Velcro to attach the finished box to the top of the water jug.
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,120
    3,046
    Neat. I'd like to see one more photo - the entire operation, dish and all.

    It'll be interesting to see how it holds up. When I clean the cat's water fountain I often find a kind of bioslime, primarily on the replaceable filter but also in slow-moving areas. I'd guess the slime will be a bigger issue than any corrosion from the small current.

    Consider the metallurgy of whatever touches the water. I don't know what paperclips are made of. Obviously, if they were made of lead or mercury, you wouldn't want to use them. Chrome sounds bad, too. We all drink from copper pipes, so I'd be tempted to go with copper even though it's more likely to corrode.
     
  4. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    The "electrodes" will disappear in days because they are biased with DC. You need to excite them with <1Vpp AC, and use an AC Ohmmeter circuit...
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,120
    3,046
    Any electrode, or were you referring specifically to my comment about copper?
     
  6. Wendy

    Thread Starter Moderator

    Mar 24, 2008
    20,766
    2,536
    At less than 3uA I kinda doubt I'll see much action for a while. You have to keep things in perspective, this is a very low power low current system.

    I may see something in a week or two, but I doubt it.
     
  7. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,043
    3,807

    At 3 uA, that is 0.25 coulombs per day.

    Faradays constant = 95000 coulombs per mole electrons (round to 100k for easy math)

    400,000 days per mole of electrons.

    2 electrons per copper atom to oxidize brings it up to 800k days per mole (63 g) copper.

    Or about 13000 days (35 years) per gram of copper.

    So, you will loose about 30 mg per year.


    In summary, it's a DIY watering dish, not a passenger aircraft.
    Cost (severity) of failure is minimal, probability of failure is minimal.
     
    JohnInTX and Wendy like this.
  8. Wendy

    Thread Starter Moderator

    Mar 24, 2008
    20,766
    2,536
    I put probe current at 2.5uA, so it is less than that. Thanks for the math, I didn't have the math tools or brains. I just knew if I kept the current as small as possible it would slow things down a lot, not to mention making the batteries last. The first electrodes are kludges, I'll tweak the shapes later. I'll also post any developments as I see them.

    I have a technicians view of the world, this is an example.
     
    GopherT likes this.
  9. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,043
    3,807
    I did some work with a plating company and I knew hundreds of amps were used there to get appreciable rates of metal transfer. When I saw your 10M ohm resistor, I knew the world would be essentially standing still at micro-ohm currents and it was a pretty good design. I only did the math to humor myself.
     
    MikeML and Wendy like this.
  10. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Thanks for doing the math. I learned something from it...
     
    GopherT likes this.
  11. flat5

    Active Member

    Nov 13, 2008
    403
    17
    Well documented project!
    If you did another one I wonder if you would use a perf board or glue it again.
     
  12. Wendy

    Thread Starter Moderator

    Mar 24, 2008
    20,766
    2,536
    Not for this kind of project. It was very quick and simple. I did have one minor problem where a solder joint wasn't made, but it was easy to troubleshoot. Basically it was a one of a kind project, good for an evening or two..

    What took me so long is punching out the printed circuit board pads I used for the sensors. I had to repair my Harbor Freight deep throat punch by buying some new metric screws. I now have a pill bottle with 10 or so similar pads ready to use.
     
    flat5 likes this.
  13. mescab

    New Member

    Jul 17, 2015
    7
    0
    Learnt so many thing from your post, thank you so much for sharing your thoughts and invention.
     
  14. Willen

    Member

    Nov 13, 2015
    138
    12
    Hi Wendy,
    I think the 7555 is a popular 555 timer. Why you mentioned as CMOS, cannot I use ordanary one. The CMOS version not available around here.
     
  15. jayanthd

    Member

    Jul 4, 2015
    274
    29
  16. jayanthd

    Member

    Jul 4, 2015
    274
    29
    You can use the smaller eTape

    http://milonetech.com/products/standard-etape-assembly

    with a PIC12LF1840 and a 3.3V Buzzer mentioned in the previous post. This will give the reading of the water level in the pet water dish. When water level is low then you can fill it with a small pump controlled by PIC.


    Your project is nice. It is simple and cheaper. Here I am attaching PIC12F1840 based project (not using eTape but using INT pin). SPST switch in circuit is replaced by alligator clips. When water becomes low INT pin is triggered and it plays a melody 3 times and then starts a timer and when timer. A counter is used in the timer interrupt and when this counter expires (approx 20 sec) then it plays the melody 3 times again and this process repeats till water is filled or battery dies.

    See video in attached file. It contains audio.
     
    Last edited: Sep 22, 2016
  17. jayanthd

    Member

    Jul 4, 2015
    274
    29
    I designed a PCB layout for your ICN7555 based circuit. It is a two layer board. If you want one layer board then I will design a new layout.
    See if you can use this layout.

    Cadsoft Eagle 7.6.0 format Schematic and Layout files are attached and also the PDF showing the actual size of the PCB.


    Pet Water Dish Alarm PCB Layout.png
     
  18. Wendy

    Thread Starter Moderator

    Mar 24, 2008
    20,766
    2,536
    Why use a programmable chip that requires special toolind just to pprogram when a simplle20 cent part wil work?This project was very simple and cheap Why build a lath toreinvent a wheel?555s are very available everywhere.Programmable is OK, not for baginners.
     
    Last edited: Sep 28, 2016
  19. Wendy

    Thread Starter Moderator

    Mar 24, 2008
    20,766
    2,536
    They allover mailoerder houses. I am flat on my backparalyzed with a stroke. Icould find one in seconds with Google.
     
    Last edited: Sep 28, 2016
  20. Kailyn Alfson

    New Member

    Dec 11, 2014
    5
    1
    A pet water dish alarm sensor could be a good invention for all pet lovers and I'm one of those. I'm looking forward to that project to be implemented. I'm hoping that it can be out in the market.
     
Loading...