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.
We found this circuit in the June 1992 issue of Radio Electronics magazine. The sensor is a common...
This circuit converts a positive CMOS supply voltage to a negative one. We found it in a 90s...
This tone control was obtained from the CA3140 datasheet, originally created by RCA. The CA3140...