The advantage of this design is that it does not need an transformer.
A simple choke will do the trick.
Another benefit is the low power consumption.
For the voltage multiplier i used ordinary 1N4148 diodes they just work fine,
The Zener is actualy a ICL8069 low voltage reference with a longterm stability of 1 ppm/kHR.
It's a bit overkill but i had one lying around so why not use it.
Sorry for the poor photo, i will change it later !
I measure the pulses from the GM tube with an microcontroller and upload the data once every
minute to the Xively database. It's a very high countrate which you wouldn't expect from an
GM tube, but it's just a very big tube.