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.
Found in a 90s 73 magazine for radio amateurs, this circuit makes use of common operational...
We found this circuit in a Popular Electronics from the 90s. Transistors can be modern...
The 4046 PLL is uncommon these days. This circuit was found in the August 1994 issue of...