|Reginald Fessenden electromagnetism
Radio receivers from 1903 until 1913 used Reginald Fessenden’s bare-point electrolytic detector to convert radio waves to pulsed direct-current signals capable of receiving either Morse code or AM signals.
How it works
A fine platinum wire immersed in an electrolyte solution acts as a rectifier for a small oscillating charge. When the oscillation gives the tip a positive charge, electrolysis of the electrolyte produces bubbles that cling to the wire to prevent current from flowing. When the oscillation gives the tip a negative charge, current flows across the electrolyte.
Not to put too fine a point on it
You mean exactly what you say about it.