Structure of a jack plug
The English name of the jack plug describes its structure: TRS connector stands for the contact areas tip, ring and sleeve. Depending on the number of rings, it is also referred to as TRRS, TRRRS or just TS. The plug tip is spherical or conical. A notch below the tip ensures that the plug is locked in place and triggers switching contacts. Each ring also carries a signal. They are insulated from each other and from the plug tip and shell. Depending on the number of rings present, a distinction is made between two-pole (one ring, mono plug), three-pole (two rings, stereo plug) and four-pole (three rings, stereo plug with additional function) versions. The sheath only has earth potential. It does not carry a signal.