Physics Journal of the Indonesian Physical Society
A GMR BASED CURRENT SENSOR
Wildian1 and Mitra Djamal2
1Department of Physics, Universitas Andalas, Padang, Indonesia 2Department of Physics, Institut Teknologi Bandung, Indonesia
For current measurement, usually we have to break or interfere with the circuit of interest. This way may take more time and tends to make the circuit broken, especially for circuits with large density and high population. In a non-contact method, we can analyze the current through a PCB trace or any other current carrying conductor without breaking the circuit. ``The basic principle of a non-contact current measurement is to measure the magnetic field created by the current surrounds the conductor radially. ``As a magnetic field sensitive material, GMR (giant magneto-resistance) can be used for detecting the magnetic field strength well. The magnetic field strength is directly proportional to the current flowing through the conductor. As the current increases, the magnetic field surrounding it will also increase and thus increase the output from the sensor. Likewise, as the current decrease, the magnetic field and output from the sensor will decrease.``Since the current is not measured directly, a correlation must be built to get the current information from the output of the sensor.``We have measured a dc current carrying PCB trace using this method.