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Automatic Watering System

Discussion in 'General Electronics Discussion' started by solution, Jun 19, 2012.

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  1. solution


    Jun 19, 2012

    I'm in a plant growing competition. I'm not allowed to buy an off-the-shelf watering system, but it occurred to me today that it may be possible to build a simple timing circuit that could dispense the water when I am not there. I have done a web search and found the following: -

    which seems ideal as I would be looking for something that would be on for ~5 seconds every couple of hours.

    The only constraint is that it must be battery-powered.

    Here are my questions: -
    1. How realistic do you think this is?
    2. How much would this cost?
    3. How long would it take?
    4. Where could I find a water valve that can be triggered by a potential and then closed? (I live in the UK)
    5. Do you have any circuit diagrams of something suitable?

    Part of the reason I want to do this is enjoyment, but if you can see a simpler solution please let me know. I have also considered buying a Raspberry Pi as programming is not a problem for me, it would just be more expensive and I'm just not sure if it would run off of a battery for many days at a time.

    Thank you.
  2. CocaCola


    Apr 7, 2012
    Very, as long as you put the effort in...

    The biggest cost factor will be the valve, if you use one... Either way not too expensive...

    You could likely build it in a few hours time, design and leg work might take a few hours to a few days...

    I would likely pick one up on Ebay, you want what is called a solenoid valve... I would source one that is 12 VDC or less to simplify things... Sound be under $20 US...

    Someone with more time might be able to work one up for you, but my time is kinda short right now...

    I would personally just use a micro to time the pulses, but a pair of 555 timers is likely better for the newbie, one to time the down time and one to pulse the one time, this allows for more flexibility in the timing, you would control the valve with a transistor&relay...

    You could skip the solenoid valve and on tap water and use a bilge/fountain pump in a bucket/tank of water...

    Unless you luck out delivery and wait times on them is still in the weeks or months... ;)
  3. solution


    Jun 19, 2012
    Thank you CocaCola.

    I'm sorry I'm using your time. I've just wikipedia'd the solenoid valve and I understand roughly how it works and I think I've found a suitable one on ebay as you suggested:

    I have another question I should have asked before: -

    • I plan to power this with 8 AAA cells in series. Neglecting the power drain from the circuit; and with the valve only open for 5 seconds every hour; I estimate this will run for aproximately 140 days. Does this sound about right?

    (I've assumed it uses no power when closed)
    Last edited: Jun 21, 2012
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