Electromagnetic Field Sensor – vero layout

updated with more sound samples Dec 2023

I have wanted to experiment with some EMF (electromagnetic field) sounds and figured I might as well make a vero layout for this EMF Sensor schematic. It’s from an article by Frank Donald that I found online. Pretty simple, using a TL071 opamp, a power inductor, a 2m pot that adjusts the frequency, and just a couple of caps and resistors. I threw it together in no time.

What is EMF?

“EMF stands for “electromagnetic field”. EMFs are invisible areas of energy, or radiation, that are associated with the use of electrical power and lighting. EMFs are a combination of electrical and magnetic fields. The strength of an EMF is related to the amount of electricity in use and the electrical potential in the electric circuit.” – National Institue of Environmental Health Sciences

and why would I want to record it?

Because it sounds weird, and if you are here, you must like weird sounds. Samples of the EMF Probe below.

With a device like an EMF sensor, you can listen to the hidden sounds that your modem, cell phone, and computer monitor make. Furthermore, you take an EMF sensor out into the world and listen to electrical boxes, phone network relays, powerlines, and even toxic radiation (according to articles, I don’t have anything radioactive to test, yet).

My EMF sensor build

I subbed the 1mH Power Inductor for a 3mH but plan on testing both now that I have a working board built. I read someplace that the lower the value the higher the frequencies passed. I say experiment.

Note: The power inductor passes power and requires a non-grounded connection if you plan on using an external probe.

~~I also had to use a 1m pot~~ and a giant 220 uF capacitor in my original build, it works but I’m sure the 2m I have on order will work even better (2.2m on the schematic).
UPDATE: the 2m does indeed add more frequency range to the EMF PROBE and is highly recommended.

Here is my finished EMF Probe!

1 Power Inductor Probe
ON/OFF/PUSH Switch
Push Button for Switch
Sensitivity Control
1/4″ Output
PROBE connected by RCA (note, must use plastic base jacks)
9 Volt Battery Operated

Go to the product page

Sounds

I collected some of these sounds in my house and a few while walking around my neighborhood. Alleyways nearby businesses seem to have pretty odd signals.