This 1968 documentation circuit uses a relay to control loads up to 1 kW (depends on relay contacts). The supply voltage depends on the relay.
Found at Popular Electronics this receiver is used with a transmitter for quadrature-coil signals....
Versions of this circuit have appeared several times on this site and even in this section. This...
This circuit provides a few watts of output and can be used in the car as an auxiliary amplifier....