A digital weak magnetic field measurement instrument based on Co-based amorphous wire is introduced.Using single amorphous-core and double-winding as the sensitive element excited by multivibrator bridge

a kind of weak magnetic sensor with small size and high performance is developed.The signal processing circuit of the sensor and the hardware circuit of the digital measurement instrument are designed

and the experimental result is given.The result shows that this instrument can measure the static state weak magnetic field ranging from-200 to +200 A/m.The measure precision of the instrument is no less than 0.5 % under room temperature.