Critical components of this project are the Geiger tube and the 300V battery. The battery can be replaced by a small inverter, as the circuit current is few microamps. The circuit is from an old documentation. Transistors are general purpose types.
August 2017 - STMicroelectronics' new DSL05 transient suppressors for 12 and 24 V voltages and...
This 6 V battery charger was found on a 1987 Hands On Electronics. Rc determines the charging...
I found this circuit in an English magazine from July 1982. The circuit is still viable because all...