Speed control for camera DC motor - has speed proportional pulses to feed frequency to voltage converter which supplies trigger

摘要

The speed control, for a camera d.c. motor, has a frequency to voltage converter to produce a d.c. voltage proportional to the motor speed. This converter contains a transistor whose input is connected to the voltage pulse source having a frequency proportional to the motor speed, and whose output is connected via a low-capacitance storage. The trigger controls the transistor that regulates the motor speed. The storage capacitor is shunted by a variable resistor. The advantage lies in the control circuit increased precision and range of proportionality.