1. Home
  2. Electronics Design
  3. EMF Detector made easy?

EMF Detector made easy?

Greetings, one.

Then perhaps you have no real idea of the potential hazard, and rely on the morass of conflicting, often misconceived studies as the basis for deciding there is an issue.

If I wanted to do that, I would probably use a simple coil pickup, followed by a high gain semi- narrowband 60 Hz filter in front of a PIC's or uP's A/D input, then implement a much narrower filter using DSP to pull what is likely to a small signal out of the noise.

It would be easy to create any display you like using software and one pin per LED or even multiplex LEDs to drive more of them. For, example, at 1 nanoTesla, the red light could blink gently. At 1 microTesla, the bar would be fully on and blinking omenously. At higher levels, you could spell out "Run for you life!",

You are welcome.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
Reply to
Larry Brasfield
Loading thread data ...

Hello one and all.

I have been looking into building a "very" sensitive EMF detector due to issues with power lines in the area. I am sorry to say that I have no REAL idea on how to do it. I was also told that there is a way to build a device that would use Hall effect sensors to measure the earths magnetic field. It would be much more sensitive and would work if adjustable. I have yet to find a circuit design that will give a visual as well as audible measurement. An LED bar graph would be ok. Any good ideas on what I could build that would do this?

Thanks for your help.

Bryan

Reply to
Bryan

"Larry Brasfield" wrote in message news:65l_d.31$ snipped-for-privacy@news.uswest.net...

[System approach using uP cut.]

Just to help promote this approach ahead of the other (as yet unseen) contenders ...

With a little extra complexity in the coil and a few switches, it could also provide an arrow to indicate which direction the irradiated user ought to run. Otherwise, given the usual arrangements in the vicinity of power lines, he might run without gaining any *real* benefit from the effort.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.
Reply to
Larry Brasfield

to

REAL

Hall

more

design

graph

It's not difficult to build, you an use a ferrite loopstick with a lot of fine wire wound on it as the sensing probe. One of these is here.

formatting link

Here's a meter using Hall effect sensors.

formatting link
formatting link

The big difficulty is calibrating it to a known standard. And they are not that expensive so there is no point in building one yourself. There are several companies that offer a calibrated EMF measurement meter for under a hundred dollars. Here's one with LEDs for under $25. Also the cellsensor mentioned below.

formatting link
Here's their main page
formatting link

Two other inexpensive meters mentioned in a paragraph from a story found with google: "I brought an am radio to the office and it would be very noisy in that office but not in the other rooms and really bad near the wall and ceiling. I then went out and bought an emf meter (cellsensor, analog meter, single axis, $42.00) and measured very high readings only in that office and the hallway. It would blink and beep like crazy even on the high setting. I did much research and talked to other engineer friends who tell me it is unconceivable to have that much emf. So I bought a digital emf meter (A.W. Sperry EMF-200A, single axis, $60.00) and proved it. I was getting over 199 mg at the wall about 2" from the conduit behind sheetrock. It went off the scale about an inch from the wall."

Reply to
Watson A.Name - "Watt Sun, th

to start, think about this

do you want to measure the ELECTRIC field at 60 Hz?

or

do you want to measure the MAGNETIC field at 60 Hz?

that is two completly different measurments.

Measuring an electomagnetic field implies you are in the far field meaning you are many wavelengths away from the source which at 60 Hz is several miles.

Mark

Reply to
Mark

I read in sci.electronics.design that Mark wrote (in ) about 'EMF Detector made easy?', on Thu, 17 Mar 2005:

Absolutely. The OP clearly understands so little about the subject that advice on making a detector is futile.

For 55 Hz, the distance is approximately 1000 km.

--
Regards, John Woodgate, OOO - Own Opinions Only. 
There are two sides to every question, except 
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
Reply to
John Woodgate

A Proton Magnetometer for entertainment/nerd value or a Flux-Gate can measure the magnetic field component - *what for* and *how to calibrate* is for the user.

Maybe easiest to buy?

The Electric component can be seen in the dark when holding a flourescent tube at one end and the other closer to the wires - The 440 kV "SuperGrid" crossing Didcot, UK will light up the tube a fair bit.

I did the experiment after getting small chocks while carrying a well-insulated child in a Nylon suit on my shoulders below the wires whenever child touched my head.

Anyway - Electrometer is the word, I think.

Reply to
Frithiof Andreas Jensen

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.