This circuit was found in a 90s American publication. The same configuration appears in several places on this site, obtained from different sources. The lamps can be replaced by LEDs.
We found this circuit in a documentation from the 50s. It is based on CK722 germanium transistors. The...
Found in an English publication from the 1960s, this circuit uses period components, including the...
This oscillator can generate 2 to 10 MHz signals and was found in an American 1980s documentation. The...