Arduino Based Magnetic Field Sensor

A couple of students I worked with this summer designed and built a VLF electromagnetic field (EMF) sensor.

Public Chat
Similar projects worth following
The project page describes the design and construction of a very low frequency (VLF 1 KHz - 400 KHz) electromagnetic field (EMF) sensor that can display magnetic field intensity (in micro-teslas) and the corresponding frequency of the magnetic field. The board is designed to work as an arduino shield and display the measured values on an LCD screen. Thus far, the first version of the board has been constructed and tested. Future revisions of the board are planned.

Enjoy this project?



RichardCollins wrote 12/17/2019 at 05:25 point


Thank you, I appreciate the clear and concise explanation.  Just "Rogowski coil" turns up background information that helps me to apply what you have done.  Otherwise it is just "arduino" and hard to understand.

This note I found just now searching for "Ragowski coil" gave  says "At low frequencies the integrator gain increases and in theory will become infinite as the frequency approaches zero. This would result in unacceptable dc drift and low frequency noise; hence the integrator gain has to be limited at low frequencies."  When you showed that you divided by omega (the angular frequency) I immediately thought that would be useful for me. As I want to look at natural signals from microHertz to 1 Hz, particularly.  If  I take this at face value, a microHertz signal would be a million times stronger in some sense, than a 1 Hz signal. 

I am working mainly in Windows on fairly powerful computers, because I want to examine closely the signals involved.  I am checking small fluctuations in the signals centered around 1 milliHertz to see if it correlates with the gravimeter, seismometer and magnetometer networks. And with the slowly varying high frequency natural signals from radio telescopes and from software defined radios at frequencies where there is no human activities, or where I have independent reference data on the human transmissions so they can be removed.

Have you thought of sharing your signals on the Internet?  The simplest is text files that are externally compressed using zip and similar compression methods.   

At these frequencies, it is hard to separate the signals. The reason I am using faster computers is because I want to sample even the microHertz signals at Msps and Gsps.  I have reason to suspect that the fields are continuous and the noise will be characteristic of the sources.  Arrays of three axis, high sampling rate sensors allow imaging to determine the location and characteristics of sources.  i am sorting through all the signals as well as I can to say whether they are magnetic, gravitational, electromagnetic or mixed sources.

The GW170817 gravitational wave event showed that the speed of gravity and the speed of electromagnetic waves is identical.  Not just close, identical. This means the two sets of waves must share the same underlying potential.  

And we might be in the situation of Maxwell finding that light and electromagnetism are part of the same overarching field.  For most practical purposes, allowing for different analog sensors to be used for gravity, magnetism and electromagnetism and heat - the seemingly different field values - meters/s^2, Tesla, Volts/meter, Watts/m^2, Joules/kg - can all be interconverted by using the appropriate energy density.   The earths gravity is equivalent to a magnetic field of about 380 Tesla (at equal energy density). That gives you some idea of potential experiments and applications.

I am trying to devise experiments to see if gravitational waves can be refracted, and absorbed (gravity just being an extension of the electromagnetic field).  Or if, in certain cases, electromagnetic fields can transmit unattenuated and unrefracted (electromagnetism then extended to include gravity.) 

With these high sampling rates gravimeters can be used to measure the speed of gravity precisely as a calibration step. And arrays can image such things as the propagating seismic waves from earthquakes.  There is a lot more. But I am trying to work things out methodically.

I will see if I can make a prediction of the properties of magnetic and gravitational sensors at these low frequencies that allows for distinquishing new things.  I am fairly certain that the entanglement experiments are seeing solutions to a nonlinear diffusion equation that applies when the sources are extended sources.  Natural sources tend to be large and massive.  The data processing and analysis have to be correspondingly sensitive to unravel that level of complexity.  it becomes a matter of processing enough information to match the information in the signals.  Stated simply, the electromagnetic data collection is generally gathering megaBytes per second to try to solve TeraByte per second problems.  So I am trying to fill that gap and see how the fields all fit together.  Communication and imaging is pretty well done. What remains it generation.  Not by moving ions, but by moving photons and electrons.

Pardon me for writing so much.  I have to constantly review from many different perpectives to see how all the parts interrelate.  I cannot do everthing, and I do not have all the pieces.  But I feel comfortable with what I wrote here and reasonably well settled, except for the entanglement. 

Richard Collins, The Internet Foundation

  Are you sure? yes | no

RichardCollins wrote 09/18/2019 at 18:51 point

Can you add some details?

What are you using for the sensor? The board is collecting and processing the data, but the magnetic field readings depend, critically, on what you use to convert the magnetic field into useable signals that your board can process, calibrate and use for practial purposes.

  Are you sure? yes | no

Alireza Dayerizadeh wrote 12/17/2019 at 02:38 point

Hello! Sorry about the late response! We actually use a 3 axis rogowski coil to detect the magntetic field. The magnetic flux(in Teslas) is equivalent to the V/wNA --- V being the voltage induced in the coil, w being the frequency of the induced voltage, N being the turns of the coil, A being the area of the coil. The vector values of Bx, By, and Bz can be converted to the scalar magnitude of the magnetic flux B by way of B=sqrt(Bx^2+By^02+Bz^2). In the case of the board here, we used various filters and amplifiers in the signal path prior to the arduino board to filter out 60Hz noise and integrate the voltage level so that the analog pin would detect only a 0-3.3V level signal. We calibrated this with a second rogowski that was just connected to an oscilloscope where we manually calculated the RMS magnetic field values using the math function of the scope. Please let me know if you need more information.

  Are you sure? yes | no

Similar Projects

Does this project spark your interest?

Become a member to follow this project and never miss any updates