Nice quote, you replied to the off this topic post from Joe Putegnat... :)
It was off topic? I thought he had a design for a sprinkler system. I was trying to get some information.
what's the difference between a relay and a mechanical actuator?
A mechanical actuator has something like a clock motor with cams that push electrical contacts together--you can't do much with that except maybe make the motor run faster or stop it. Remember Armitron? A robot arm toy. That turned out to be cams and levers inside. Or consider animating a manual typewriter (not that any of us ever did *that*).
A relay can be controlled by switching a current on and off. So, you just rip out the factory brains, and drop in your own. Because the factory designed the right electronics to drive the valves for you--and they give you a proper power supply along with it. (Assuming you trust the factory design...from people who name their stuff "Ecxtra"...) What I call the "brains" just decides *when* to open the valves.
As nobody was willing to touch "sun synchronous" :-) What happened here was that I am aware that micros don't keep very good time, unless you add some more hardware. So I thought, with a light sensor, you could watch the sun rise and set, and that would be close enough.
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