| 摘要 |
PURPOSE:To set plural speeds without requiring a switch with >=2 electrodes by detecting the impedance of a resistance connected to an input terminal, and driving and stopping a sewing machine and controlling its rotating speed during the driving on the basis of the impedance. CONSTITUTION:When switches 52 and 54 are both off, the impedance between terminals (e) and (d) is infinite, so the output of a converting means 41 drops below a reference voltage vs and the sewing machine is still off. When one switch 52 is turned on, a variable resistor 51 is connected, so setting the impedance to r1 allows the converting means 41 to output a voltage v3 and the sewing machine rotates at the rotating speed corresponding to the voltage. When the switch 54 is turned on, a variable resistor 53 is connected, so setting the impedance to r2 allows the converting means 41 to output a voltage v4 and the sewing machine rotates corresponding to the voltage. |
