This filter was found in an American publication from the 1980s. The circuit can be implemented with any operational amplifier. The power supply must be symmetrical.
Suggested by Sprague in the 90's documentation, this circuit applies to AC motors. The...
We found this circuit in Electronics Now magazine from December 1995. Any operational amplifier can be...
This circuit was found in Sgnetics documentation from the 80's. The circuit also has loudness...