The Electronics section of Changpuak, has calculation tools for electronic circuits as well as some electronic projects like power supplies, signal generators and curve tracers too .
Among others they also have Amplifier Design, Antenna and Filter Designer AF and RF and Basic Electronics Tutors.
A Geiger–Müller tube consists of a tube filled with a low-pressure (~0.1 Atm) inert gas. (Helium, Neon, Argon,…). The GM-Tube has a coaxial shape, where the inner conductor (Anode) is biased with a high voltage (~500V) relative to the outer conductor (Cathode). The Tube has a window (left side) made of mica.
Homebrew Geiger Müller Counter – This GM-Counter is build on 2 PCB’s. One is a standard high Voltage generating circuit, whilst the second is a Counter based on an ATMega16™ which also handles serial Communication with a host (Environmental Control).