Found in Popular Electronics from the 1980s, this circuit uses two operational amplifiers from that time. The circuit has frequency and symmetry adjustment.
This circuit was obtained from a 1967 General Electric documentation. The circuit makes use of...
This configuration uses the 4 gates of a 7401 integrated circuit. The capacitors determine the...
This filter can be used to eliminate hum in sound equipment. Operational amplifiers can be 741 and...