The circuit presented was found in the Linear Applications Handbook of the National Semiconductor of 1994. It is based on a DAC1020 and operational not common today.
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...