This 50 Hz rejector or notch filter was found in a 1975 documentation. Other frequencies can be obtained by changing components. The filter uses a Wien network and must use a symmetrical power supply.
Found in a1967 Ferranti documentation, this circuit uses an operational amplifier from that time....
May 2017 - ROHM is announcing the availability through Mouser Electronics of a broad line of fast...
This circuit was adapted from an Italian publication that no longer exists. This is “Onda Quadra”...