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 a1980s Motorola documentation. The integrated circuit is from that time....
This circuit is a variation of the previous one, indicating a voltage range, for example 11.5 to...
This circuit was obtained in a 90’s American documentation. The FET can be replaced by a modern...