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, from a 1990 documentation, can serve as a basis for a game of target-game. The...
While BC547 is not a suitable transistor, it can work on this circuit. The ideal would be the...
This power supply that we found in an old American documentation uses an integrated circuit that...