| 摘要 |
PURPOSE:To improve the reliability by utilizing the Hall effect to detect a magnetic field produced by an incoming call current. CONSTITUTION:A notch is provided to a part of a ring core on which a coil 1 is wound and an electronic circuit 2 assembled with a Hall element and an amplifier circuit is arranged at the notch part. When an incoming call arrives, an incoming current flows to the coil 1 thereby producing a magnetic field. A Hall voltage is produced to an electrode of the Hall element through this magnetic field, amplified by the amplifier and outputted. Since no semiconductor is used in a circuit throughout which the incoming current flows, the circuit withstands noise induced on a line and miniaturization is also attained. |
