This 5-tube hi-fi amplifier was found in an American publication from 1947; The output is in class B and the circuit uses a source with transformer.
This oscillator is enabled when a high level is applied to the control input. The operating...
This circuit uses two oscillators to produce a sound that seems the sound of a ring-bell. The...
Found in a Popular Electronics from the 9s, this circuit has output for RS-232 interfaces and current...