Arbitrary Magnetic Field Generator System

In order to allow fast, in house testing of developed magnetic sensors and magnetometers a special test/calibration instrument has been developed. It consists of a 3D Helmholtz coils equipped with a feedback triaxial fluxgate sensor and a specific electronics which includes fluxgate signal processing circuits, output amplifier capable of driving 650 mm diameter coils and a precision offset current source. The whole setup allows to generate an arbitrary magnetic field vector with up to 200 μT magnitude, while suppressing the background magnetic noise which is very intense in our lab due to the nearby tram and subway lines. It uses linear output amplifiers so it does not produce broad spectrum of electromagnetic interference, as do some commercial systems.

Control unit (Power switch, OLED display, USB and RS232 control interfaces, status LED and “X!” switch)
Control unit (Power input, Feedback sensor interface, Output to Coils)
Inside… multiple power sources and signal/control/interface electronics
“Bicycle style” 3D Helmholtz coils, F – feedback sensor, M – magnetometer (Device Under Test)
Triaxial fluxgate sensor used for the feedback compensation
SW (Qt) allows for manual and automatic control of the system, with the vectors shown one can rotate a compass placed in the coils…
X: PWM, Y: short, Z: MCU 3V3 …in the instrument
MCU power supply current – 2 mA change, period 20-40 s