| 摘要 |
A control for an electric motor for producing a first control signal for controlling the speed of the motor and a second control signal for controlling the direction of rotation of the motor includes a pair of photocells connected in series across a power supply, a light source for illuminating the photocells, a movable mask for controlling the intensity of illumination on each of the photocells, a pair of switches and a pair of actuator members one of which is associated with each of the switches. An output terminal is connected between the series-connected photocells for producing the first control signal, the magnitude of which controls the speed of the motor, and is dependent upon the resistance of the photocells and hence the intensity of illumination acting thereon. The switches produce the second control signal. Initial movement of one of the actuating members effects activation of its associated switch to thereby produce the second control signal and further movement of the actuating member effects movement of the mask to thereby control the intensity of illumination acting on the photocells so as to control the magnitude of the first control signal. Thus, movement of one of the actuating members controls the direction of rotation of the motor associated with the control and the magnitude of movement of the actuating member controls the speed of the motor.
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