A keel-shaped needle with a titanium electrode layer would ride in the groove with extremely light tracking force, reading the electrical signal from the groove where it is decoded from an FM state into video and audio signals.
A keel-shaped needle with a titanium electrode layer would ride in the groove with extremely light tracking force, and an electronic circuit was formed through the disc and stylus. This in turn altered the frequency of a resonant circuit, and this signal was then decoded from an FM state into video and audio signals.