This circuit was found in American documentation from the 90's. The circuit applies to any operational. The power supply can be between 5 and 15 V depending on the operational.
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...