OpenSprinkler AC to DC / Triac to Transistor

– 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. 

the 8 triacs (one is already taken out)
Diagram of a the circuit with flyback diode!
Every diode works like the 1N4001. 
The new transistor BC337 in place – the legs have to be bend a lot.

Here a possible way of build in a TIP120 :

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