Hacking a water timer

  • Hero Member

    We have a bunch of horses and we need to fill the water troughs several times a day. Trouble is, we sometimes forget to turn off the water which results in 100 m² of wet wood shavings that have to be shovelled out and replaced. In an effort to fix this I bought a water timer from our local cheap things shop. Unfortunately this was designed to water plants with the only possible settings on, off, and turn on for X minutes every Y hours. It was cheap, though, so I bought it thinking that I could hack it. It turned out that I was not able to control the motor inside the unit directly, but I could manipulate the input signals for the on-board microprocessor. By using a relay and shorting two different circuits I could turn the water on and off digitally 🙂

    Add a button, a LED, some environmental sensors because why not?, And of course the radio module and we have something fun that works.

    Each press of the button adds one minutes to the "on" time. As long as this time is greater than zero keep the water running, and shut it off when the timer expires. Every 15 seconds the LED blinks to indicate the number of remaining minutes of on time. Long press the button to reset the time and shut off the water. The state of the switch and the time remaining is relayed to domoticz as a light switch and a distance sensor (the closest match I could find). The light switch can of course also be triggered from domoticz, giving us multiple options for turning on and off the water. Turning on the water from the computer simply sets the timer to 10 minutes to ensure that it will be automatically shut off at some point.

    It doesn't look great, but it's solves a real problem 🙂

  • Contest Winner


    H20 + electricity = fun!!!

    just kidding, GREAT idea!!

    I think I could use this for watering some flowerbeds!

  • Hero Member

    I'm actually slightly worried about that. Since I needed to count time and to receive packets I can't have it sleeping all the time. That means it has to be run off of mains power instead of batteries (the water thing itself runs on batteries)., The 220 V extension cord is someways away from the thing, so the only power that reaches near water is 5 V. I don't expect this to be a serious problem, but you never know.

    On the other hand, we use heating cables inside the water pipes to keep them unfrozen during winter which is the full 220 V (and this is done professionally) so my 5 V shouldn't be a problem 🙂

  • Nice! Would add a water detector in one of those containers. Just in case no water at all arrives.... 🙂

  • Hero Member

    @betonishard That is actually a good idea, although I would have to do that with a separate sensor since the barrels are in a different room. I envision the following:

    I have three wires into the barrel. One is at the bottom (ground), and the two others are affixed to the side (digital inputs). One at a low position and one at a high position. I can then detect when the water is low and when it is high.

    Makes sense? Or is there a better way of doing this?

  • @kolaf maybe a distance sensor at an angle on top off the barrel. You could than measure exact figures in some way??i don't know (just a noob)..

  • Hero Member

    without underestimating the fun and ingenuity of your project, wouldn't a toilet float valve work better and more reliably to shut the water off when the barrels fill?

  • Hero Member

    @Moshe-Livne I agree that a floating valve would be a better solution if you had a fixed installation. This would allow you to keep the water on at all times and have the water barrel top itself off continuously. We have such a system, but it is a pain to run the pipes to everywhere the horses need the water, especially in winter when it's freezing. This means we have one of these, but the rest are filled using a regular hose.

    The implemented solution works well for having a hose lying around and stretching it to wherever we need to fill the buckets without wasting water or ruining the area by getting too wet. This has happened several times already, and not only was it a pain to clean up, but it also emptied our well so we had to go down and manually restarted everything by filling the system with water.

    In short, it is a failsafe system to guard against our own forgetfulness with a great deal of flexibility 🙂