This frequency triple oscillator circuit was found in an American publication in 1967. The FET is current and more detailed information about the coils is not given.
MCP19124/5 Contains Independent Voltage and Current Control Loops Plus a Full Suite of...
A flash of light on one sensor or the touch of your fingers on the other type of sensor will turn...
This 1-transistor timer was published in Radio Electronics magazine in December 1960. The circuit has...