This circuit was found in Texas Instruments documentation from 1968. The transistors are from that time, admitting modern equivalents. The response ranges is from 20 to 20 000 Hz.
We found this circuit in the 1983 Radio Electronics Special projects magazine. The components are...
This filter for scratched disc noise was found in an English documentation from 1989. The...
The operational amplifier used in this application is not the most common today. The circuit is...