This is one of many possible touch switch configurations using CMOS integrated circuits. The circuit is from a 1980s American documentation. The power source must be isolated.
Critical components of this project are the Geiger tube and the 300V battery. The battery can be...
The instrument is a common multimeter on the lower voltage scale. The FET can be BF245 or MPF102. The...
Suggested by National Semiconductor in a documentation of the 90s, this circuit uses a power...