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 interesting circuit found in an American documentation from the 70's generates signals of...
The FETs of this circuit can be the BF245. The circuit is from an old documentation and can be...
This circuit can either generate signals in the astable form or be synchronized externally,...