Three-Axis Magnetic Field Generator

Project

The Three-Axis Magnetic Field Generator allows users to explore electromagnetism by creating stable magnetic fields in three independent directions. The goals of this project are:

• Educational Demonstration: The generator provides users with instant visual feedback on how their input affects the magnetic fields, enhancing their intuitive understanding of electromagnetic laws.
• Instrument Calibration: The calibration of scientific devices such as magnetometers require precise, controlled magnetic fields. This generator creates these fields to facilitate this calibration.
• Device Testing/Verification: Devices such as pacemakers, cochlear implants, and other Actively Implanted Medical Devices (AIMDs) require testing to characterize their resiliency to magnetic fields. The generator creates magnetic fields strong enough to test these medical devices.

System

Methods

Using a magnetometer paired with control software, the generator drives three pairs of wound copper coils (Helmholtz coils) to create stable magnetic fields following user input.

• Helmholtz Coil Design: Using equations that relate currents to magnetic fields, an excel sheet was used to design the coil dimensions and windings
• Physical Construction: Using the CAD software Onshape, the system was modelled for fabrication.
• Power Amplifier Circuitry: The ESP32 microprocessor provides signals to the power amplifier circuits, which supply the currents required to produce +/-500 μT magnetic fields.
• Controller Software: The control system (see System) computes desired magnetic field outputs based on magnetometer data.
• User Interface: A 2-inch LCD provides the user with visual feedback while three potentiometers and a rotary encoder allow the user to adjust the magnetic fields.

Conclusions

• Magnetic Field Strength: The generator successfully produces a magnetic field with amplitude 500 μT.
• Magnetic Field Stability: The generator provides a stable and controlled magnetic field via software control.
• Magnetic Field Volume: The generated magnetic field is near constant in a volume of 4x4x4 inches.