A motor control apparatus for an unbuffered reel-to-reel drive system including independently operable first and second drive motors including first and second sensors for detecting rotation of reels and a circuit for controlling the drive motors cooperatively to maintain tension applied to a tape. The...http://www.google.de/patents/US4664336?utm_source=gb-gplus-sharePatent US4664336 - Motor control apparatus for reel-to-reel tape drive system
