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.
This circuit was obtained in a 1978 English magazine. This adjustable stabilized power source...
This circuit was found in old documentation, but as it uses the 555 it can still be easily...
This timer with field effect transistors was obtained from Fairchild documentation. The times...