Current CPM:
After 10 hours of use, the device gave a spark sound and stopped working.
The replacement unit also doesn't work reliably: after some power-on hours, the count declines to 0 CPM. Might have something todo with the high voltage being too high. I measured
f = (10.10 MΩ + 0.94 nS) / 10.10 MΩ ≅ 106
9.073 V × f ≅ 965 V
The 3rd replacement started giving 2,000 CPM after some time.
Source code
Sven Killig 2011