Author Topic: Moteino Based Drip Irrigation Valve  (Read 814 times)

TomWS

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Moteino Based Drip Irrigation Valve
« on: July 28, 2017, 05:55:04 PM »
After doing my battery operated Sprinkler Valve controller (https://lowpowerlab.com/forum/projects/moteino-based-battery-operated-sprinkler-valve/) a few years ago (and several refinements since), that design has fairly stabilized, but it made me realize that I had a gap in my set of irrigation tools.  Namely, I discovered that I didn't have anything that could inexpensively and somewhat discreetly keep small planters or groupings properly watered. 

For example, we have several window boxes that are under eaves and never get watered.  We have several large pots with various herbs that keep struggling when there isn't enough rain.  All of these have individual watering needs but very low demand.   This definitely begs for a drip irrigation valve that is small and inexpensive and can be powered throughout a growing season on a single set of batteries.

This last requirement left most valves out of the question and the first two requirements left out the latching valve I used on the Sprinkler Valve project.

After many different attempts to produce a small, reliable, low cost, energy efficient valve, I think I finally have one worthy of long term testing.  This valve uses several 3D printed parts to make a cam operated pinch valve.  Being 3D printed, the parts cost pennies (if you ignore the cost of the printer  ;)

The cam is driven by a low cost gear motor with a magnet positioned at the high lobe and two hall sensors on the PCB to know when it's open or closed.

Additionally, I decided to try a ceramic antenna (the radios run at 915MHz) with the fallback option to switch to bare wire or u.fl connector if need be.  The results of this are quite surprising with the gateway seeing -65db RSSI with the radio powered at 1dbm (I'm using RFM69HCWs).  The distance isn't far, but the gateway is in the house on the second story, with the valve enclosure located about 50-60 feet away UNDER the Window Box.  You can see the antenna in the lower right corner of the PCB in the photos below.

Finally, the drip valve can operate somewhat autonomously since it has its own moisture probe attachment.  You can see the potted circuit board in the enclosure photo.

When the design has been shaken down, I'll post the design files (at least circuit, not sure about the 3D parts).

Tom

TomWS

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Re: Moteino Based Drip Irrigation Valve
« Reply #1 on: July 28, 2017, 05:56:20 PM »
Adding photo of enclosure since it wouldn't fit in original post.

TomWS

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Re: Moteino Based Drip Irrigation Valve
« Reply #2 on: July 28, 2017, 05:59:21 PM »
And, just to show the kind of 'learning' that took place, here is a photo of the previous tubing I attempted to use.  I tried a thin wall silicone tube that wouldn't take much pressure to close.  As you can see, even 12PSI supplied by the water supply turned that into a balloon as soon as the valve closed!  Fortunately it didn't blow up, but I'm surprised it didn't!

Felix

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Re: Moteino Based Drip Irrigation Valve
« Reply #3 on: July 31, 2017, 08:22:56 AM »
Very nice, I bet we could learn a lot from anything else you might share, I might have some interest in making one of these myself ;)
« Last Edit: July 31, 2017, 09:05:19 AM by Felix »