This circuit is from a 1968 Motorola power circuit manual. The circuit uses transistors of the time. The passing band is 45 Hz to 100 kHz.
I found this circuit on a December 1976 Radio Elettronica. The Italian magazine no longer exists, but...
This circuit for the power grid was found in the June 1969 Radio Electronics magazine. The load is...
This circuit with common CMOS components was found in the November 1984 issue of Radio Electronics...