Experimental Induction Magnetometer

This is an experimental device that uses fluctuations in the Earth's magnetic field to directly generate a voltage in a copper coil. It's purpose is to see if we can detect fine-scale changes in the local magnetic field caused by space weather.

Induction magnetometers are made up of thousands of turns of fine wire (typically 100,000 turns). I wanted to experiment with one, but they are time-consuming to make and the industrial-sized quantity of fine magnet wire is not cheap! It occurred to me that a car ignition coil has about 10,000 turns on the secondary and that buying a bunch of them and wiring the secondaries in series might be cost effective enough to test the concept. Thus Frankencoil was created!

The coil has a radio frequency shield around it so it only picks up the magnetic component of the total electromagnetic spectrum. It is aligned N-S magnetic.

Because the induced voltage is so tiny, a simple amplifier is used to boost the signal. This is fed into the microphone-in port of a PC. Next, I use Spectrum Lab to capture and record the signal, along with some custom code written in Python to parse out daily log files for display here.

At the moment Frankencoil is used to look at a harmonic associated with the 50hz mains hum which appears to follow the diurnal variation of the Earth's magnetic field.

There is still some work to go, but if Frankencoil performs well enough in a geomagnetic storm, then it might be worth the money to get a proper induction magnetometer made.