What is an EMF meter really for?...

[Tim R]

I came across an article about a cattle mutilation and the guy was using an EMF meter to look for aliens or something. His meter detected them, no surprise.

I thought the EMF meter was invented by the movie industry, but apparently they are real. Google tells me they are widely purchased by ghost hunters. shudder! Not much hope for humanity. But I digress.

So is there an actual use for one, maybe in electronics engineering or something? I haven\'t seen one discussed in this group, I did search.

What do they do, and why?

 

[KenW]

On Wed, 1 Jun 2022 14:35:27 -0700 (PDT), Tim R
<timothy42bach@gmail.com> wrote:

I came across an article about a cattle mutilation and the guy was using an EMF meter to look for aliens or something. His meter detected them, no surprise.

I thought the EMF meter was invented by the movie industry, but apparently they are real. Google tells me they are widely purchased by ghost hunters. shudder! Not much hope for humanity. But I digress.

So is there an actual use for one, maybe in electronics engineering or something? I haven\'t seen one discussed in this group, I did search.

What do they do, and why?

I did a search and found loads of information. Try it !


KenW

 

[Mike Coon]

In article <d9216cff-a4d7-42df-b5ae-a95902e8ad81n@googlegroups.com>,
timothy42bach@gmail.com says...

I came across an article about a cattle mutilation and the guy was using an EMF meter to look for aliens or something. His meter detected them, no surprise.

I thought the EMF meter was invented by the movie industry, but apparently they are real. Google tells me they are widely purchased by ghost hunters. shudder! Not much hope for humanity. But I digress.

So is there an actual use for one, maybe in electronics engineering or something? I haven\'t seen one discussed in this group, I did search.

What do they do, and why?

What is your definition of \"real\"? Would anything sold by Gwyneth
Paltrow qualify? There are reasons for wanting to know what the electric
field strength is...

 

[Jeff Liebermann]

On Wed, 1 Jun 2022 14:35:27 -0700 (PDT), Tim R
<timothy42bach@gmail.com> wrote:

I came across an article about a cattle mutilation and the guy was using an EMF meter to look for aliens or something. His meter detected them, no surprise.
I thought the EMF meter was invented by the movie industry, but apparently they are real. Google tells me they are widely purchased by ghost hunters. shudder! Not much hope for humanity. But I digress.
So is there an actual use for one, maybe in electronics engineering or something? I haven\'t seen one discussed in this group, I did search.
What do they do, and why?

EMF (electro-magnetic field) can be anything from 60 Hz power line
radiation, to microwave emissions. The real EMF meters were designed
to help measure specific EMF fields for measuring things like cell
phone SAR (specific absorption rate), unwanted emissions for FCC type
certification, radio/TV broadcast station antenna pattern, EMC
(electromagnetic compatibility) testing, and personal RF safety such
as might be encountered when working on a radio tower. Some typical
applications:
<https://www.narda-sts.com/en/applicationstechnology/occupational-safety/>

Typical equipment:
<https://www.narda-sts.com/en/all-products/>
<http://www.extech.com/categories/electromagnetic-field-meters>
<https://www.google.com/search?q=rf+field+strength+meter+3+axis&tbm=isch>
Personal EMF meters:
<https://en.wikipedia.org/wiki/Personal_RF_safety_monitor#Gallery>

The low cost junk sold online is at best a crude imitation of a proper
EMF meter mostly because they do not produce meaningful measurements
that can be useful for design, installation, testing, and
verification.

If you purchased a junk EMF meter like this:
<https://www.ebay.com/itm/363819859401>
to find ghosts or determine if something might fry your brain, your
brain is already fried. I have to confess that I bought one of these
and found it useful for finding 60 Hz power line radiation but not
much else. The sensitivity decreases rapidly with increasing RF
frequency.

Good luck
--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Tim R]

On Thursday, June 2, 2022 at 12:00:52 PM UTC-4, Jeff Liebermann wrote:

If you purchased a junk EMF meter like this:
https://www.ebay.com/itm/363819859401
to find ghosts or determine if something might fry your brain, your
brain is already fried. I have to confess that I bought one of these
and found it useful for finding 60 Hz power line radiation but not
much else. The sensitivity decreases rapidly with increasing RF
frequency.

I won\'t claim a fresh brain but the advertising hype on these products did peg my BS meter.

On the other hand, at about $20 for some of the cheapies, would they be useful to avoid hitting a power line drilling through a wall or digging in the garden? You mentioned 60 Hz power line radiation.

 

[Jeff Liebermann]

On Thu, 2 Jun 2022 09:36:52 -0700 (PDT), Tim R
<timothy42bach@gmail.com> wrote:

On Thursday, June 2, 2022 at 12:00:52 PM UTC-4, Jeff Liebermann wrote:

If you purchased a junk EMF meter like this:
https://www.ebay.com/itm/363819859401
to find ghosts or determine if something might fry your brain, your
brain is already fried. I have to confess that I bought one of these
and found it useful for finding 60 Hz power line radiation but not
much else. The sensitivity decreases rapidly with increasing RF
frequency.

I won\'t claim a fresh brain but the advertising hype on these products did peg my BS meter.

Well, maybe a baked brain.

>On the other hand, at about $20 for some of the cheapies, would they be useful to avoid hitting a power line drilling through a wall or digging in the garden? You mentioned 60 Hz power line radiation.

No. The AC wiring in the wall is too narrow and probably too far away
for the junk EMF meter to accurately locate it.

I have one of these, which has an AC wiring locator feature:
<https://www.zircon.com/instructions-documentation/multiscanner-pro-sl-instructions/>
The current version is probably better:
<https://www.zircon.com/tools/metalliscanner-m60c/> $55.
This older one should work and is cheaper:
<https://shop.zircon.com/multiscanner-440/> $30.
I also borrow an AC circuit tracer and circuit breaker tracer from the
neighborhood electrician as needed:
<https://www.amprobe.com/product/at-6030/>
You probably won\'t like the price. $1,800 list.

One catch. These tend to use 9V batteries, which are becoming rather
expensive. I\'ve been switching to rechargeable LiIon 9V batteries:
<https://www.ebay.com/itm/125325078582>
About $5/ea, which is the same as alkaline but is rechargeable and I
don\'t have to worry much about devices that draw current even when
turned off.


--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

 

[danny burstein]

In <nslh9h1vu1a9q44vaabmtuj4gelidgva3l@4ax.com> Jeff Liebermann <jeffl@cruzio.com> writes:
[snip]

EMF (electro-magnetic field) can be anything from 60 Hz power line
radiation, to microwave emissions.

60 Hz? Newbie. 25 CPS is the way to go

--
_____________________________________________________
Knowledge may be power, but communications is the key
dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]

 

[Tim R]

On Thursday, June 2, 2022 at 8:01:44 PM UTC-4, danny burstein wrote:

60 Hz? Newbie. 25 CPS is the way to go

--
_____________________________________________________
Knowledge may be power, but communications is the key
dan...@panix.com
[to foil spammers, my address has been double rot-13 encoded]

I hope you\'re not one of the old fashioned types who still hang on to pi - surely you\'ve converted to tau like all the cool people?

 

[Wond]

On Thu, 02 Jun 2022 09:36:52 -0700, Tim R wrote:

On Thursday, June 2, 2022 at 12:00:52 PM UTC-4, Jeff Liebermann wrote:

If you purchased a junk EMF meter like this:
https://www.ebay.com/itm/363819859401
to find ghosts or determine if something might fry your brain, your
brain is already fried. I have to confess that I bought one of these
and found it useful for finding 60 Hz power line radiation but not much
else. The sensitivity decreases rapidly with increasing RF frequency.


I won\'t claim a fresh brain but the advertising hype on these products
did peg my BS meter.

On the other hand, at about $20 for some of the cheapies, would they be
useful to avoid hitting a power line drilling through a wall or digging
in the garden? You mentioned 60 Hz power line radiation.

At the simple end, a Field Strength Meter- antenna, diode, meter; at 60Hz
you\'d need a big antenna, probably a coil.

 

[Jeff Liebermann]

On Fri, 3 Jun 2022 00:01:39 -0000 (UTC), danny burstein
<dannyb@panix.com> wrote:

In <nslh9h1vu1a9q44vaabmtuj4gelidgva3l@4ax.com> Jeff Liebermann <jeffl@cruzio.com> writes:
[snip]

EMF (electro-magnetic field) can be anything from 60 Hz power line
radiation, to microwave emissions.

60 Hz? Newbie. 25 CPS is the way to go

Hardly. I prefer my power delivered as DC as Edison and the other
patriarchs of power transmission intended it. For a time (early
1970\'s), I had wall outlets that delivered 12V DC[1]. Before cheap DC
to AC inverters were available, using 12V DC was quite common in
recreational vehicles. Fortunately, some organizations are
re-discovering the benefits of DC power:
<https://en.wikipedia.org/wiki/High-voltage_direct_current>
<https://oca.dc.gov/page/dcplug>
such as no electromagnetic radiation.


[1] The commodity wall outlets worked as long as I didn\'t plug/unplug
the power cord while DC current was flowing. If I forgot, the current
would arc weld the power plug to the receptacle. Running AC wall
switches on DC had the same problem. DC connectors and switches were
too expensive, so I gave up.

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

 

[bilou]

On 03/06/2022 17:33, Jeff Liebermann wrote:

Fortunately, some organizations are
re-discovering the benefits of DC power:
https://en.wikipedia.org/wiki/High-voltage_direct_current
https://oca.dc.gov/page/dcplug
such as no electromagnetic radiation.

On your second link it seems that DC stands for \"district of Colombia\"

 

[Peter W.]

Jeff:

Either you have a rare sense of humor, or you are genuinely certifiable - or, hopefully, both.

Peter Wieck
Melrose Park, PA

 

[danny burstein]

In <gu9k9h5s2dar7i7h53496dfoj195ciu7l1@4ax.com> Jeff Liebermann <jeffl@cruzio.com> writes:

[snip]

Hardly. I prefer my power delivered as DC as Edison and the other
patriarchs of power transmission intended it. For a time (early
1970\'s), I had wall outlets that delivered 12V DC[1].

Parts of NYC had DC utility power as late as the 1990\'s. While Con Ed
stopped new hookups 1960ish, they kept the legacy wiring live
a lot longer.

My 6 story apartment building with 28 apartments had regular AC,
but _ALSO_ had DC coming in for the elevator (a pretty common
situation) and ... had an \"unmetered\" (flat rate) separate low current
feed dedicated for the fire alarm.

A friend of mine lived in a similar apartment building
on 110th and Columbus Ave 1975ish, and believe it or not...
the rooms there had standard outlets, some of which
provided, sit down for this... 120V **DC**. Yes, identical.

We figured it was cheaper for the landlord to pay off the
building inspectors than to rewire...

Note that since we\'re talking 1975 (and earlier),
people had many appliances (basically incandescent
lamps) which would, indeed, work ok. But don\'t
plug in your record player.

would arc weld the power plug to the receptacle. Running AC wall
switches on DC had the same problem. DC connectors and switches were
too expensive, so I gave up.

Would the liquid mercury based wall swiches (remember them?) have
worked ok?

--
_____________________________________________________
Knowledge may be power, but communications is the key
dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]

 

[Jeff Liebermann]

On Fri, 3 Jun 2022 18:29:42 +0200, bilou <bilou@sfr.fr> wrote:

On 03/06/2022 17:33, Jeff Liebermann wrote:
Fortunately, some organizations are
re-discovering the benefits of DC power:
https://en.wikipedia.org/wiki/High-voltage_direct_current
https://oca.dc.gov/page/dcplug
such as no electromagnetic radiation.

On your second link it seems that DC stands for \"district of Colombia\"

You\'re right. I screwed up. I thought they were installing an
underground DC power line. Sorry.

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Fri, 3 Jun 2022 22:50:53 -0000 (UTC), danny burstein
<dannyb@panix.com> wrote:

In <gu9k9h5s2dar7i7h53496dfoj195ciu7l1@4ax.com> Jeff Liebermann <jeffl@cruzio.com> writes:

[snip]

Hardly. I prefer my power delivered as DC as Edison and the other
patriarchs of power transmission intended it. For a time (early
1970\'s), I had wall outlets that delivered 12V DC[1].

Parts of NYC had DC utility power as late as the 1990\'s. While Con Ed
stopped new hookups 1960ish, they kept the legacy wiring live
a lot longer.

My 6 story apartment building with 28 apartments had regular AC,
but _ALSO_ had DC coming in for the elevator (a pretty common
situation) and ... had an \"unmetered\" (flat rate) separate low current
feed dedicated for the fire alarm.

A friend of mine lived in a similar apartment building
on 110th and Columbus Ave 1975ish, and believe it or not...
the rooms there had standard outlets, some of which
provided, sit down for this... 120V **DC**. Yes, identical.

We figured it was cheaper for the landlord to pay off the
building inspectors than to rewire...

Note that since we\'re talking 1975 (and earlier),
people had many appliances (basically incandescent
lamps) which would, indeed, work ok. But don\'t
plug in your record player.

Amazing. I would have thought that 120V DC would have disappeared
long ago. I did try 120VDC on my house electrical system to see what
would happen. It was similar to the 12VDC arcing and contact welding
that I experiences with 12VDC. I also got a few shocks. 120VDC was
quite different from a 120VAC shock. I think I may have pulled some
ligaments or tendons from the rapid muscle contraction.

would arc weld the power plug to the receptacle. Running AC wall
switches on DC had the same problem. DC connectors and switches were
too expensive, so I gave up.

Would the liquid mercury based wall swiches (remember them?) have
worked ok?

I don\'t know. I didn\'t have any mercury switches and none of the
stores had them for sale. I would guess(tm) that the major problem
was the glass bulb exploding from something that produces hot gases
from the arcing. No oxygen, therefore no combustion or burning. With
just mercury and some kind of contacts, there\'s nothing that can burn,
so I guess it might be safe. However, I would be worried if vaporized
mercury could sustain an arc across the contacts, which would not be a
good thing. Probably a bad idea.

I thought that mercury had been banned in consumer products in the
1960\'s, but now I find that it wasn\'t until 2001 that California
finally banned mercury switches and thermostats:
\"DTSC SB 633: California’s Mercury Reduction Act of 2001\"
<https://dtsc.ca.gov/publications-index/mercury-publications/>

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

 

[KenW]

On Fri, 3 Jun 2022 22:50:53 -0000 (UTC), danny burstein
<dannyb@panix.com> wrote:

In <gu9k9h5s2dar7i7h53496dfoj195ciu7l1@4ax.com> Jeff Liebermann <jeffl@cruzio.com> writes:

[snip]

Hardly. I prefer my power delivered as DC as Edison and the other
patriarchs of power transmission intended it. For a time (early
1970\'s), I had wall outlets that delivered 12V DC[1].

Parts of NYC had DC utility power as late as the 1990\'s. While Con Ed
stopped new hookups 1960ish, they kept the legacy wiring live
a lot longer.

My 6 story apartment building with 28 apartments had regular AC,
but _ALSO_ had DC coming in for the elevator (a pretty common
situation) and ... had an \"unmetered\" (flat rate) separate low current
feed dedicated for the fire alarm.

A friend of mine lived in a similar apartment building
on 110th and Columbus Ave 1975ish, and believe it or not...
the rooms there had standard outlets, some of which
provided, sit down for this... 120V **DC**. Yes, identical.

We figured it was cheaper for the landlord to pay off the
building inspectors than to rewire...

Note that since we\'re talking 1975 (and earlier),
people had many appliances (basically incandescent
lamps) which would, indeed, work ok. But don\'t
plug in your record player.

would arc weld the power plug to the receptacle. Running AC wall
switches on DC had the same problem. DC connectors and switches were
too expensive, so I gave up.

Would the liquid mercury based wall swiches (remember them?) have
worked ok?

The phone company in NYC had 105v 20cps for ring tone sent to feeds at
least till 1973 when I quit. Probably for old switchboards and pbx\'s.
I got zapped a few times in backyards testing phone troubles. IT WAS
HOT !!


KenW