Geiger counter with high voltage source (CB22333E)

This circuit includes a high voltage inverter to power a Geiger tube. We found it in an American documentation from the 60s.

Two Integrated AM Receiver (CB21208E)
This simple radio was found in a Popular Electronics from the 90s. L1 and L2 have 100 turns on a...
Smart Charger (CB26305E)
This circuit was found in Radio Electronics magazine from the 90's. The circuit is for small NiCad...
12V Battery Charger (CB4971E)
This automotive circuit was obtained from an 80's schematic from the integrated circuit factory...