Fluxgate Magnetometer Report.pdf

The project aimed to design and implement a fluxgate magnetometer, a high-precision magnetic field sensor. The device consists of two coils and a magnetic core, and its technology was invented in 1936 to detect submarines. The team constructed a fluxgate magnetometer that demonstrates toroidal drive, signal processing with phase demodulation, and ammeter functionality with display.

Key Components

1. Toroid and Sense Coil Construction: A toroidal core is used to drive the core to saturation, and a sense coil is placed around the toroid to detect external magnetic fields.
2. Timing and Toroidal Drive: The timing circuitry drives the toroidal coil into positive and negative saturation with frequency f.
3. Sense Signal Extraction: The sense coil picks up a signal proportional to any external magnetic field present, which is then extracted to a sine wave of frequency 2f.
4. Phase Demodulation: The extracted 2f sine wave signal is fed into a phase demodulation circuit to extract a DC voltage output that demonstrates magnitude and directionality of magnetic field.
5. Ammeter and Display: The system includes an ammeter with display for magnitude and directionality of current with LED’s and a speaker.

System Overview

The fluxgate magnetometer is divided into five components: timing circuitry, sense coil, phase demodulation, ammeter, and display. The system uses a rod core and a toroidal core to achieve a means by which the core can be driven to saturation and the sense coil can detect a signal of double the drive frequency. The sense coil uses a turn count of about 500 turns of 38 gauge magnet wire.

Applications

Fluxgate magnetometers are widely used in industry and academia due to their affordability, ruggedness, and compactness. They have applications in earthquake detection, solar phenomenon detection, and NASA's CubeSat units. The technology has been miniaturized to the point of IC sensor solutions with recent technology.