Noise Reduction Characteristics of Current Sensors Using Amorphous Multi-Core Multivibrator with Negative Feedback Loop

New small sized high performance current sensors are presented using an amorphous multi-core multivibrator bridge with a negative feedback loop. Serially connected 8 pair cores are set around a conductor with a current I to detect without contact a magnetic field H (=I/2¿r) cancelling external disturbance fields. Currents of ¿200 to 200A (¿40 to 40 Oe) from DC to 5 kHz are stably detected with an error of less than 0.4% FS and 0.2% FS for non-linearity and hysteresis, and temperature stability of 0.009% FS/°C for -196°C to 200 °C. The cancelling mechanism of external fields in the multi-core arrangement is analyzed for disturbances originating from a conductor current and a magnetic dipole.