This circuit is from a Popular Electronics from the 90s, consisting of a repeater relay for remote control of TV, which today can be done by Wi-Fi or other simpler resources.
This circuit includes the power supply from the power grid. We found it in Radio Electronics from...
We found this circuit in a 2003 publication. The indicated coil is for capturing the signals in an...
This circuit is from a 1967 publication. The configuration holds true for modern transistors having...