Hi
I build a Geiger counter, based on the Russian SMB-20 tube.
He HV circuit is based on the following design
http://https://sites.google.com/site/diygeigercounter/circuit-description
I made a small video of the device, the clicks you can hear are background radiation.
http://http://www.youtube.com/watch?v=ZEmLzNCHv8Y
The next step is to add a micro controller to count the impulses and display them on a lcd.
Btw.
The design is also capable to drive the new counter tube from Seedstudio.
http://http://www.seeedstudio.com/depot/j408947-geiger%C3%82%E2%80%93m%C3%83%C2%BCller-tube-p-834.html?cPath=144_194
Cheers
Rubi
Great work! I've always wanted to build something like this...