| 摘要 |
PURPOSE:To display in high reliability the energizing state of a drive coil by electromagnetically coupling the drive coil of a synchronous motor to the secondary coil and connecting a light emitting diode between the output terminals of the secondary coil. CONSTITUTION:A secondary coil 7 is provided to electromagnetically couple it to the drive coil 10 of a synchronous motor 1. A current limiting resistor 5 and a light emitting diode 8 are connected in series between the output terminals of the coil 7. When a commercial power source 3 is connected to the terminals 2a, 2b, the motor 1 rotates, and induced electromotive force is simultaneously generated at the secondary coil, and the diode 8 is fired. On the other hand, when a drive coil 101 is disconnected so that the motor 1 becomes impossible to operate, no induced voltage is generated in the coil 7, and the diode 8 is deenergized. |
