Condition: By means of a roughly 50 micro Ampere DC current generated with the aid of a 9 Volt battery, a signal of about 2 (two) Herz and higher (occurring between the hand palms touching iron plates, for instance) is obtained.
Problem to be solved: To make the signal audible - meaning, changed into an intelligible sound that reflects the pattern of change, which would be the amplitude (magnitude of change), and frequency (speed and acceleration of change).
Specifically: To make an increasing range audible, that is, beginning with the range of about 2 to 10 Herz, and switch to expand to a bigger range of about 2 to 20 Herz, then 2-50 Herz, and also 2-100 Herz. And eventually up further.
Any circuit design suggestion and recommendation of components is appreciated - the results are intended for the public domain.
Koos Nolst Trenite human rights philosopher and poet