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Squirty Boy

An open-source DIY irritation controller.

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I am creating a RasPi based irrigation controller, to reduce the irritation of starving plants.
I was initially inspired by the high price of multiple zone irrigation controllers, but I also wanted to create an open version which others could use and expand for greater capability. Perhaps someday I will sell DIY kits. I will keep everything as open as possible, maybe GPL if I ever get around to reading it...

So far, homie is designed to be completely solid state and allows the user to decide if the valves will run on AC or DC, but not both ATM. I am also powering the Raspi from the same supply as the valves, cuz I dont want a bunch of cables cluttering my yard. Current to the valves can be limited by a series of Thru-Hole resistors.

Here is the datasheet for the valves I am currently trying to interface with:
https://stc.dripdepot.com/files/8413/8413-HV%20TECH%20SPEC.pdf

Here is the website for FarmOS, which included support for reading and logging sensor data on networked devices.
https://farmos.org/

I currently have a dedicated computer running as a server to provide FarmOS on my home network.

Once the controller is complete I will probably create a series of  other sensors which could be managed by the RasPI as well, but one step at a time.

Zip Archive - 95.35 kB - 04/06/2020 at 10:15

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  • Transformer Learnin' Time!

    greenscum04/24/2020 at 08:05 0 comments

    O, I have a scrounged AC transformer I was hoping to power this with. It has 16 (?!)  ~12v secondary windings, which I had chained all up to give me around 30V to rectify and regulate for powering the Raspi. However it seems the over-all current supplied by these many taps is just barely insufficient to power a bare Raspi 4. I am able to measure the transformer output current to about 1.5A, but this is not quite enough. I can see on the scope where it dips as the RASPI tries to boot, sucks too much juice, and then shuts down for a second in a lamentable waltz for watts. I have tried disabling various components on the RASPI with no luck... So I am going to have to order a new transformer to power this box.

    I am pleased with the ability of the diodes and beefy 3905 to convert 30Vac to a clean 5Vdc. The ripply DC hitting the regulator IC is ~40V!

    I suspect the plethora of taps is reducing the total current of this transformer; The wires in the secondary windings are tiny, which I believe is what limits the available current of a transformer. If I was using something better suited, such as a 1:5 transformer with a single beefy secondary winding, I probably would not be having this problem! Sadly, sometimes recycling old parts to drive vastly over-powered microcomputers does not work.

  • PCB and Parts Arrived!

    greenscum04/14/2020 at 20:49 0 comments

    Now to see where I screwed up in the design. Its obvious I should spend more time measuring things out in PCBnew to make sure everything matches the footprints in the datasheets. Even so, it looks like only minor changes will be necessary!

  • First version PCB complete?

    greenscum04/06/2020 at 10:11 1 comment

    I spent another few hours fiddling with kicad and I think I have a workable PCB ready. I will upload the files when I remember where the appropriate place is.

    I am going to sleep on it and then order a batch of boards and bits in the AM!

  • Triac test!

    greenscum03/06/2020 at 01:15 0 comments

    I have done a successful proof of concept for using a triac to switch the AC voltage for my valves! Now to design the PCB

  • Thyristors or MOSFETs?

    greenscum02/22/2020 at 09:02 1 comment

    10 more minutes of duckduckgo-fu has led me to believe I want to use Thyristor chips instead of MOSFETs. While it is a bummer that these are 100x+ more expensive, it seems to be much more appropriate than running two MOSFETS in reverse bias.

    I will research this more tomorrow.

  • First sketch.

    greenscum02/22/2020 at 08:50 0 comments

    I have created a first sketch in KiCad of how I imagined the circuit would work, and uploaded it as a ZIP archive. First I added a power section which will take the 24VAC from a 120VAC transformer and then rectify filter and regulate to 5V to power the RasPi, then I added a MOSFET relay control section which will actuate the solenoids in the water valves. I need to learn more about how to control AC with MOSFETS, so if anyone has any good guides or circuit examples it would be greatly appreciated.

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