If you are fairly tech savvy, this isn’t hard to do.
I have built a few sprinkler valves using an esp8266, relay, solenoid, and esphome. Total cost of each one is less than $15 (US). If you are willing and patient, you could probably get that to under $10 via aliexpress.
The circuit is really simple -
Parts list:
- 12v power supply
- DC to DC converter
- Microcontroller (esp8266 or esp32)
- 5v relay
- 12v solenoid valve
- Plastic enclosure (use old Tupperware or 3d print something)
Outline:
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Run power supply to dc-dc converter, and set converter to output 5v.
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Connect one leg of 12v through switch on relay, then to the solenoid.
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Connect other 12v leg directly to solenoid.
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Run 5v from output of buck converter to input of esp and relay.
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Run data wire from esp pin to data input in relay.
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Put everything but the solenoid in a plastic box.
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Run water source to solenoid inlet and connect sprinkler or drip system to solenoid outlet.
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Flash esp with esphome
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In the esphome code, you will need the home assistant api, a switch, and a sprinkler component.
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In home assistant, set a switch or button on your front end to test everything with and provide manual control
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Write a basic home assistant automation to control via timer, or weather conditions, or soil hydration, or whatever.
You can do all of this without any soldering or any (real) programming - that being said, those two skills will improve the results by quite a bit, and are just useful in general for this sort of work.
It can (of course) get as complex and full featured as you like, but if all you want is a system that can water your flowers every time the ISS passes overhead, the above will get you there pretty cheaply.
I have been doing home automation for almost 30 years. I started with x10, and still have a few x10 devices deployed in my house, so I think I’m in a position to know what I’m talking about here.
There are a few major advantages Zigbee and Zwave have over x10, namely:
Now there do exist some wireless battery powered x10 devices (the MS16A motion sensor, for example or the DS10A door sensor). These are actually fairly solid devices, and I still use a good number of them in my home. (I have many DS16As that have been in daily use for more than 20 years)
It isn’t all bad, and there is no reason to throw it all out if it works for you. However, if you are buying new gear to automate with, there isn’t really a compelling reason to go back to X10. the modern solutions are cheaper, faster, more secure, and easier to work with.