I found this and other beautiful circuit drawings whilst foraging in the derelict back buildings and basement of the Rundfunk der DDR, Funkhaus Nalepastrasse. Even thought the main building is still used for recording and performance, the back buildings are a hive of discoveries for the explorer with skip-raking tendencies with all sorts of communicative artefacts lying around from 70's intercoms to glass tanks for battery making.

This circuit is the most complex, and produces a variable EM output that is detectable by the previous two circuits.

A more complex circuit with more components, limiting the input to lower frequencies.

Basic EM amplification circuit with simple wire antennae.