Small Detection System Of Magnetic Fuse

A detection system based on magnetic sensor was proposed to detecting magnetic moving objects. The system consisted of a sensor module, amplifier circuit, filter circuit, data acquisition circuit, reset circuit and power supply module, which was suitable for non-contact detection.The underlying theory of magnetoresistivity was introduced. The magnetic sensor chip HMC1002 was used as its performance of target detection. Considering the weak output signal and the additional interference signal caused by Wheastone bridge circuit, a signal processing circuit and MCU software control decision-making circuits was designed. As the property of sensor will turn bad, when encountered a strong magnetic field interference (higher than 5 Gauss), a reset circuit was designed to enhance its sensitivity.The amplifier circuit included a first amplification circuit, which using integrated amplifier chip AD623,and a second amplifier circuit consist of single-chip integrated chip OPA2338,which received the output signal from A/D converter chip DAC7311 and the first amplification circuit. Controlled by the DAC7311,the second amplifier output signal can be stable in the default interval and input to the MCU as the final sample signal. Based on the principle of mean filter algorithm, a filtering algorithm suited for this detection system was proposed, furthermore, the voltage stabilized algorithm and detection algorithm have been improved as well.Finally, each part of system had been tested,which included the first amplifier circuit test, second amplifying regulator circuit test, waveform of moving metallic object and moving metallic targets test. By analyzing the results, several factors were proposed to account for the failure of remote detection.