This circuit synchronized by the power grid can be used as a shield. We found it in an 80's Electronic Engineering. R1 can typically be 4k7.
The configuration shown can be applied to modern operational amplifierso with common power...
This circuit appeared in Radio Elecronics magazine in 1968. The operating circuit is a...
The circuit shown is from a September 1973 Radio Electronics. It reduces the full scale of a...