I kind of forgot a flyback diode when designing this, I did remember and the Unit I built has a 1N4007 soldered underneath across the +Ve and Fan terminals of the power connector.
I wanted to integrate it into the design, and I needed to fix a path probelem with the KiKad libraries for the sensor and DigiSpark, so I sat down and did a minor update on the PCB design. I dont intend to make this, but it looks fine. Also.: all the resistors are now flat on the board, they interfered with the case before.
I updated the schematic to add some notes and correct a badly labelled pin.