Found in a 1964 Electronic Design, this circuit shows how to modulate a signal with a dynamic low impedance microphone. The circuit operates in the FM range (88 to 108 MHz).
Today we have more compact solutions. This is from a Radio Electronics magazine from October 1990....
This filter was found in Texas Instruments documentation from the 1980s. The circuit uses a common...
16 commercial test circuit for tubes and transistors appeared in Radio Electronics magazine in...