Control circuit for DC motors in film cameras - avoids overshoot and sluggish response by using load-dependent feedback and brake

摘要

The control circuit is for dc motors that set a film camera's aperture and avoids the problems of overshoot and sluggish response in existing circuits by employing load-dependent feedback and providing a braking device for the motor. The brake may be mechanical (or given braking moment), or electrical. If electrical, it may be formed by the low dynamic internal resistance of the bridge that drives the dc motor, or by a shunt circuit in parallel with the motor, or by the feedback circuit itself. The input variable to the control circuit consists of the output of a photosensitive resistor.