Position Indicating Circuit for a Foot Controller of a Sewing Machine, and Detecting System Using the Same

A detecting system for a sewing machine, the sewing machine including a main body, and a foot controller that includes a pedal, said detecting system comprising:

• a position indicating circuit used to be installed in the foot controller, and including a first input terminal for receiving a first voltage, a second input terminal for receiving a second voltage, an output terminal, a first resistor and a second resistor, said first resistor having a first terminal that is coupled to said first input terminal, and a second terminal, said second resistor having a first terminal that is coupled to said second terminal of said first resistor, a second terminal that is coupled to said second input terminal, and a third terminal that is coupled to said output terminal, said second resistor being used to be actuated by the pedal such that at least one of a first resistance provided thereby between said first and third terminals thereof or a second resistance provided thereby between said second and third terminals thereof is variable according a position of the pedal, and such that a voltage at said output terminal has a magnitude related to the position of the pedal;
• and
• a detecting circuit used to be installed in the main body, and including a detecting module and a determining module, said detecting module including a third resistor and a fourth resistor, said third resistor having a first terminal that is for receiving a third voltage, and a second terminal that is capable of being coupled to said first input terminal of said position indicating circuit and that provides the first voltage, said fourth resistor having a first terminal that is for receiving the third voltage, and a second terminal that is capable of being coupled to said output terminal of said position indicating circuit, said detecting module generating a detection voltage with reference to a voltage at said second terminal of said fourth resistor, said determining module being coupled to said detecting module for receiving the detection voltage therefrom, and determining, based on the detection voltage, whether said position indicating circuit and said detecting circuit are coupled to each other.