We found this circuit in a Popular Electronics of the 90s. The circuit can be easily mounted today, as the components are common. The SCR can be the TIC106.
This small source was found in an English documentation from 1970. The diodes can be 1N4002 for...
-- We find this configuration very simple in a previous American publication of 1973. The...
This double T oscillator configuration can employ operational diamonds and the symmetrical supply...