– please don’t forget the flyback diode –
OpenSprinklerPi usually works with AC because Alternating Current is most effective if you are working with coils. (due to the inductance) In an allotment garden where we only have solar power – DC is the thing. 🙂
The RaspberryPi works with DC of course and even the OpenSprinkler board works normally with DC. The only thing which is different to the DC version is that triacs are used to control the valves. So we have to change them.
The good thing: they are controlled just like a transistor. The Gate on a triac is what the Base is on a transistor.
We can use a NPN BC337 wich may be to small for some projects. As i want to switch 1A for a couple of minutes i will use a TIP120.
Here a possible way of build in a TIP120 :