This 1924 receiver uses a battery for the tube filaments and a high voltage battery for the amplifier and detector circuit. The speaker is kind of high impedance era.
This circuit was found in a 1967 US documentation. The FET is general purpose and the 6V zener....
This High Side Current Sensor was found in a 2005 Linear Technology manual. The current sensing...
Found in American documentation from the 90's, this circuit is very current and can be implemented with...