This circuit was found in a 90’s 303 Circuits. The components are from the period and the heating system depends on the resistive element.
This circuit was found in a 1974 Ferranti transistor manual. The frequency is given by the...
This oscillator that generates signals below the audible range (sub audio or infrasound) was found...
This simple 3-transistor radio with earphone was found in a 1967 documentation. The circuit uses...