This circuit for music effects and synthesizers was found in a Radio Electronics issue from June 1974. The circuit also consists of a pulse width modulator.
A second type of bandpass filter, which uses only an operational amplifier, is shown in the...
This low power circuit for the FM band was found in a spy book from the 90s. The tunnel diode is...
This oscillator uses germanium transistor avaialble in 1958 when the project was published....