το βελάκι δεν το καταλαβαίνω, και θα επιμείνω σε ό,τι έγραψα πριν
από wiki
Modern TS and TRS connectors are available in three standard sizes. The original 1/4″ (6.35 mm) version dates from 1878, for use in manual telephone exchanges—making it possibly the oldest electrical connector standard still in use. The 3.5 mm or miniature and 2.5 mm or sub-miniature sizes were originally designed as two-conductor connectors for earpieces on transistor radios. The 3.5 mm and 2.5 mm sizes are also referred to as ⅛″ and 3/32″ respectively in the United States, though those dimensions are only approximations. All three sizes are now readily available in two-conductor (unbalanced mono) and three-conductor (balanced mono or unbalanced stereo) versions.
TRS = 3 conductors, Tip - Ring - Sleeve