This circuit by Ferranti, in a 1967 publication, is intended for reading perforated tapes. The circuit uses transistors from the era that can be replaced by modern equivalents.
The signal itself captured by the (long) antenna serves to feed this simple experimental circuit....
In the figure below we have two triggers made with the LM3900 transconductance operational...
This common circuit using a multivibrator causes two lamps to alternately flash at a frequency and active...