Today i soldered together the fan controller as sketched in the last log entry:

To mount the fan i bought my self a 100mm wall mount for air ventilationand attached the fan to it. To seal it off i used some silican to keep the air outside when the fan is off:

The first testrun was a success - the fan started to blow air when switching on GPIO 23 (to which the controller is connected via the fan controller above)