This circuit is from a 1980s Motorola documentation. The circuit can be made with modern equivalent components. The original circuit is for the 115 Vac (110 V) grid and has two settings.
In this circuit, D.A. which is actually O. A. of an operational amplifier, which can be any type...
A narrow range of frequencies around 1 kHz is rejected by the high Q filter shown in the figure,...
This circuit, which uses a planar silicon sensor, is from a 1964 Electronic Design. The component...