Found in a documentation from the 70s, this circuit can be implemented today with ease. The relay is of the alternating current type.
The signal itself captured by the (long) antenna serves to feed this simple experimental circuit....
This voltage level-triggered circuit was found in a 1969 Ferranti English documentation. Modern...
This amplifier makes use of a simple 12 to 30 W source, having been found in the SGS manual of...