Described in an article in the March 1979 issue of Radio Electronics magazine, this generator was used in an audio test station. The frequencies are given by the capacitors.
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...