Found in old American documentation, this receiver transmits signals via the power grid. We can use it on links or remote control. The components admit equivalents.
This circuit is from a 1976 Motorola CMOS manual. It can be implemented with modern Darlingtons like...
In the figure we have the way of modulating or controlling the frequency of a relaxation...
The purpose of this circuit is to monitor the operation of an alternator in cars with a 12 V...