The figure shows how to couple two CMOS circuits using an optical coupler to achieve isolation. The circuit is from a Radio Electronics from August 1992.
This interesting circuit measures the distortion of the sinusoidal voltage of the power grid. We...
The operational amplifier used in this old application is not common today, but more modern...
Used in 1950s CW receivers, this type of circuit used germanium transistors. The circuit has...