@yoshida hi!
Im not sure where you get that #9 should be A5? Looks right to me. The pin is connected to pin 9, and that is D3.
For a rotary encoder, it depends on your input - but don't you want an analog signal in? In that case you use the analog pins.
Edit: offcourse, if you use a module converting it to digital like described in the the build section you use a digital pin.
@mfalkvidd said:
I am using them at 12V so the power would be ~4W. Not too much but still enough to get the sink hot!
The voltage makes no difference. 5A is still 5A.
you are right brain fart
The choice of MOSFET can be tricky. Seems that irlz44n was discontinued so you may need to find one adapted to the voltage and current you want to handle.
In all the cases you need to get a logic MOSFET too, meaning that they are fully open usually around 1 to 3V.
Also I'm sort of confused as it seems to me that L7812CV is a Voltage regulator, not a MOSFET. So if you are actually using that in the MOSFET spot it will definitively not work.
Especially if you are handling high current or voltage I would recommend using one from a reputable source for your MOSFET, I recently switched from mouser / digikey / aliexpress to mostly use http://www.arrow.com as you get free regular shipping, event if you order a couple of components (no affiliation to them whatsoever).
I didn't think the voltage drop would make enough of a difference to notice, but i guess it does. I might have to research and look for a more efficient Mosfet.