Found in a 1924 publication, this 2-valve receiver has a speaker output. Power comes from several batteries. Information about the coils is given.
Found in Popular Electronics from the 90s, this circuit uses a reed switch on the rails as a...
This oscillator does not carry any resonant circuit, except for the one formed by the crystal...
The circuit shown in the figure causes a piezoelectric transducer to emit interval beeps. The 100...