This circuit is from a 1924 book by Gernsback. The receiver uses two tubes and listens to headphones. Power is supplied by battery with the indicated voltages.
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...