We found this circuit in an Electronic Design. The main integrated circuit is the 4017. The frequencies are determined by the RC circuits as well as the duration of the generated pulse train.
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...