| 摘要 |
A speed control device for the motor of a home sewing machine, comprising, a comparator having one input connected to a reference voltage, an output connected to the motor and another input, a first control circuit with a variable resistor connected to the other input of the comparator and a second control circuit with a low motor speed constant resistor and a switch connected to the same other input of the comparator. A voltage sensor is provided between the first and second control circuits and the stated other input of the comparator so that the motor is operated at a low motor speed corresponding to the constant resistor of the second control circuit when the variable resistor of the first control circuit is in its higher resistance position and for switching the control of the motor to vary according to the variation of the variable resistor in the first control circuit when the resistance of the variable resistor in the first control circuit falls below that of the constant resistor and the second control circuit. |
