摘要 |
<p>The tape material roller drive system is particularly for use in photographic processing machines, having a variable-speed direct-current motor. An electrical switching stage (2) is connected in the supply to the motor (1), preferably in that to the armature (1a). This is regulated by a switch unit (12) reacting to the value of the current through the motor. The switch unit can be a controllable semiconductor, preferably a thyristor, functioning at a predetermined amount of voltage drop at a resistance (8) in the motor supply circuit, and causing the switching stage to cut off this supply.</p> |