FET Switches

Both the pump and the vacuum solenoid valve are controlled by FET switches. Wire the supplied FETs as follows:

FET

The control pin for pump is TinyG’s “Spin” and for vacuum, it is pin “Cool”.

I soldered the FET directly to the connector I used:

FET on connector

The FET selection is not critical. the supplied FET is either STD30NF06L or FDD6680AS. The former used to be my “go-to” low level logic FET, but has been unavailable for some time (as of November 2021). The latter is more or less equivalent.  If you are building the machine without using the kit, any FET that switches on with a 3.3V control signal should work.