Searching \ for '[OT:] Microwave ovens was WIFI Waveguide antenna' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: massmind.org/techref/index.htm?key=microwave+ovens
Search entire site for: 'Microwave ovens was WIFI Waveguide antenna'.

Exact match. Not showing close matches.
PICList Thread
'[OT:] Microwave ovens was WIFI Waveguide antenna'
2004\08\02@131732 by Robert B.

flavicon
face
The way I understand it, any escaped microwaves would only heat me up.  I
don't ever feel warmer when the microwave is running, therefore I am not
very concerned.  The oven's rating is 800W, 2450MHz.  Even if all that
radiation escaped in a concentrated beam, it would still be far below many
commercial microwave transmitters.  I've heard stories of tech's sitting
near the microwave transmitter beams to keep warm in the winter, so I'm
still having trouble believing a little microwave radiation leakage could
actually do any damage.

I'm certainly no expert, and if you have a source indicating that it is
actually dangerous I'd love to read it.  I'm sure there are some HAMs on
this list (apparently you, Dave?) who know all about microwave radiation and
might have a link or two so I could learn about it too.

So far in my research I've discovered that the FDA advocates less than
2mW/cm2 leakage for new ovens.  This is apparently to avoid interfering with
communications devices rather than protect the biological species using the
microwave.

At any rate, I probably shouldn't let my friend do this anymore:
http://nerdulator.net/misc/ian.JPG



{Original Message removed}

2004\08\02@133843 by David VanHorn

flavicon
face
At 12:17 PM 8/2/2004, Robert B. wrote:

>The way I understand it, any escaped microwaves would only heat me up.  I
>don't ever feel warmer when the microwave is running, therefore I am not
>very concerned.  The oven's rating is 800W, 2450MHz.  Even if all that
>radiation escaped in a concentrated beam, it would still be far below many
>commercial microwave transmitters.  I've heard stories of tech's sitting
>near the microwave transmitter beams to keep warm in the winter, so I'm
>still having trouble believing a little microwave radiation leakage could
>actually do any damage.

RF safety is not so easy.
You can develop cataracts in your eyes from this sort of thing, but not immediately.
DONT screw around with it.

I'm licenced for 1500W (which to me is silly and obscene at this frequency) but you wouldn't find me anywhere near the antenna when operating.  Even at 1W I would not want to be anywhere close to the antenna.

I'm not a hysterical reactionary, but I do believe in the inverse square law. :)

http://www.telecomlab.gr/2002/oct/rhodes/pap3rs/N%20108%20(p775%20-%20p780).pdf

The antennas on my car, are on the other side of a nice metal roof. Very little energy gets inside.  I don't use an HT much, and when I do, I keep the antenna away from my head.

>At any rate, I probably shouldn't let my friend do this anymore:
>http://nerdulator.net/misc/ian.JPG

Me, I would cut off the AC cord, take it out to the trash, and bash in the door with a brick.

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email spam_OUTlistservTakeThisOuTspammitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@140834 by Denny Esterline

picon face
> At any rate, I probably shouldn't let my friend do this anymore:
> http://nerdulator.net/misc/ian.JPG
>

Depends on how much you like him... :o)

-Denny

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email .....listservKILLspamspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@141250 by Lawrence Lile

flavicon
face
Don't bash in the door - get inside the thing and take the magnet out of
it.  Believe me it is worth it, takes a screwdriver and about 2 minutes.
There are two SERIOUS magnets inside an 800 watt microwave - the kind of
magnets that will pinch a blood blister on your fingers if you get a
pinky between two of them.  That is what I use for refrigerator magnets
- you can put a framed picture of Mom on the fridge and it won't fall
off! Heat up a screwdriver and stick it on this magnet and when it cools
off it is a magnetic screwdriver.
Also, the microwave oven is totally and completely disabled if you take
out the magnet  <grin>
-- Lawrence Lile, P.E.
Electrical and Electronic Solutions
Project Solutions Companies
http://www.projsolco.com


> {Original Message removed}

2004\08\02@141705 by David VanHorn
flavicon
face
At 01:09 PM 8/2/2004, Lawrence Lile wrote:

>Don't bash in the door - get inside the thing and take the magnet out of
>it.  Believe me it is worth it, takes a screwdriver and about 2 minutes.
>There are two SERIOUS magnets inside an 800 watt microwave - the kind of
>magnets that will pinch a blood blister on your fingers if you get a
>pinky between two of them.

What shape?

> That is what I use for refrigerator magnets
>- you can put a framed picture of Mom on the fridge and it won't fall
>off! Heat up a screwdriver and stick it on this magnet and when it cools
>off it is a magnetic screwdriver.

Yes, I suppose so. Still for the average guy, the potentially charged filter cap is a significant hazard. The disassembly could be a little bit interesting.


>Also, the microwave oven is totally and completely disabled if you take
>out the magnet  <grin>

Kinda lets the mag out of the magnetron.. :)


I do have an article reprint on making an AM TV transmitter by adding a modulator to a microwave oven. Theoretically workable, but I don't know anyone who has done it.

Even my buddy WA1MKE (known around here as "microwave dave") hasn't taken that plunge yet.

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listservspamKILLspammitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@143337 by M. Adam Davis

flavicon
face
David VanHorn wrote:

>At 01:09 PM 8/2/2004, Lawrence Lile wrote:
>
>
>>magnets that will pinch a blood blister on your fingers if you get a
>>pinky between two of them.
>>
>>
>
>What shape?
>
>
Probably a puffy ovoid shape, but it depends on how much skin gets
between the magnets... :-)

-Adam

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email .....listservKILLspamspam.....mitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@151113 by Lawrence Lile

flavicon
face
> What shape?
>
Doughnut shaped, about 8cm diameter and 3cm thick



> Yes, I suppose so. Still for the average guy, the potentially charged
> filter cap is a significant hazard. The disassembly could be a little
bit
> interesting.

Oh Yeah, make sure you find that cap and stick a screwdriver across it.
It is supposed to have a discharge resistor across it, but sometimes
they fail...

>
>
> >Also, the microwave oven is totally and completely disabled if you
take
> >out the magnet  <grin>
>
> Kinda lets the mag out of the magnetron.. :)
>
Yeah, sorta like a airplane without the air, or a rocket ship without
the rocket, or a pistol without the ... (hey this is a family list
here..)

>
>
> Even my buddy WA1MKE (known around here as "microwave dave") hasn't
taken
> that plunge yet.
>
I thought Microwave Dave was doing 10-20 after that last mod.  
--Lawrence Lile

> --
> http://www.piclist.com#nomail Going offline? Don't AutoReply us!
> email EraseMElistservspam_OUTspamTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listservspamspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@155228 by Roland

flavicon
face
At 02:06 PM 02/08/2004 -0500, you wrote:
>> What shape?
>>
>
>Doughnut shaped, about 8cm diameter and 3cm thick
>
>
>
>> Yes, I suppose so. Still for the average guy, the potentially charged
>> filter cap is a significant hazard. The disassembly could be a little
>bit
>> interesting.

Years ago I put a magneron in the bandsaw to get a good look inside.
interesting. I'm sure you could get KW's out of it by applying the correct
DC to it. (+cooling)

Anyway, I really don't like the idea of handling powerful DC magnets.
Another one of those 'unknown long term effects' like RF and the rest.

Back to the 'countdowm..' topic, a magnetic field is necessary for life on
earth, and so we are susceptable to magnetic fields in general. Something
the scientists don't adress is that an artificial field is needed for deep
space travel. Also then, scanning planets for magnetic fields is a first
test for possible life.

Regards
Roland Jollivet

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email @spam@listservKILLspamspammitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@165120 by Lawrence Lile

flavicon
face
> Back to the 'countdowm..' topic, a magnetic field is necessary for
life on
> earth, and so we are susceptable to magnetic fields in general.
Something
> the scientists don't adress is that an artificial field is needed for
deep
> space travel. Also then, scanning planets for magnetic fields is a
first
> test for possible life.
>

I'd have to agree that a magnetic field around the planet is necessary
for a good radiation shield.  I am not so sure why a field is necessary
to sustain an astronaut, provided he is inside a suitable can of some
kind, or an alien slime mold, provided he is built like a cockroach and
doesn't mind a few gamma rays for breakfast.  
>
> Anyway, I really don't like the idea of handling powerful DC magnets.
> Another one of those 'unknown long term effects' like RF and the rest.
>

So far those "unknown long term effects" have produced nil as far as
repeatable, statistically signifigant effects from magnetic or electric
fields commonly encountered.  
On the other hand, the public has been panicking about this for years,
since the 80's when one study found a slight statistical correlation
between proximity to substations and some kind of cancer.  Nevermind the
study was on a small population, positive results were never replicated,
and was repeated many times over with negative results, the public is
still frothing at the mouth about it.  It resurfaced when somebody sued
because they had a cell phone and happened also to get brain cancer, a
coincidence, and the public has grabbed onto that anecdote and used it
as proof, jury and judge.  
Scientists can pack rats into cages with all kinds of magnetic fields
for years and find no ill effects vs controls, and these studies have
been done over and over again because the public keeps demanding it.
They "know" that emf causes disease and don't believe any other result.

> Regards
> Roland Jollivet

On the other hand...  maybe you are right!  <GRIN> <moves away from
monitor, buys handsfree ten foot pole for his cell phone>
--Lawrence

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email KILLspamlistservKILLspamspammitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@165706 by John J. McDonough

flavicon
face
----- Original Message -----
From: "Lawrence Lile" <RemoveMEllileTakeThisOuTspamPROJSOLCO.COM>
Subject: Re: [OT:] Microwave ovens was WIFI Waveguide antenna


> Oh Yeah, make sure you find that cap and stick a screwdriver across it.
> It is supposed to have a discharge resistor across it, but sometimes
> they fail...

And don't use your favorite screwdriver!

--McD

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email spamBeGonelistservspamBeGonespammitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@180012 by Robert Rolf

picon face
What always amuses me about the 'panicked public' is that
the body's intrinsic operating voltages (across nerve
membranes) are on the order of 50kV/meter. ORDERS of magnitude
above what you would get from typical external EM fields.
Muscles also produce 100's of millivolts, again over tiny
scales, so you have low kV/meter all the time (remember that
your heart is beating all the time and you do have to breath).

External EM fields are down in the noise compared to what
body cells are exposed to on a continuous basis.
And the body electrolytes are highly conductive, highly
attenuating higher RF frequencies with depth.

And if the 'radiation' is non-ionizing, the worst that can
happen is that you get warmed up a bit, which is not a problem
since your blood carries away the heat. The only body part
that is not protected by this cooling process is the lens and
cornea of the eye. Cook those (42C+) and you DO have a problem,
but nothing fatal.

I work in Neuroscience, and have reviewed the literature because
of the RF excited implanted stimulators we use for rehab. FES.

There are also TNS (Transcranial Neural Stimulators) which create
kilo Tesla fields to directly stimulate deep brain regions.
None of the 10's of thousands of patients exposed to these
fields has ever been reported as having come down with brain
cancer or related diseases, and given the sample space and EM
strength, this SHOULD have happened if there were a causal
relationship.

And lets not forget the statistics of TENS OF MILLIONS of
cellular phone users, and their NOT having brain cancers
at anything above random rates.

Robert
The sky is falling... NOT!

Lawrence Lile wrote:

{Quote hidden}

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email TakeThisOuTlistservEraseMEspamspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@180632 by David VanHorn

flavicon
face
At 02:06 PM 8/2/2004, Lawrence Lile wrote:

>> What shape?
>>
>
>Doughnut shaped, about 8cm diameter and 3cm thick

Hmm. Might be fun to scrap out some old units.
Not rare earth, NIB, right?

>Oh Yeah, make sure you find that cap and stick a screwdriver across it.
>It is supposed to have a discharge resistor across it, but sometimes
>they fail...

I always assume they have failed.

>>
>>
>> Even my buddy WA1MKE (known around here as "microwave dave") hasn't
>taken
>> that plunge yet.
>>
>
>I thought Microwave Dave was doing 10-20 after that last mod.

?? Dave's an instructor at the academy, at Ball State Univ.

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email RemoveMElistservspamTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@181221 by Bob Blick

face picon face
> What always amuses me about the 'panicked public' is that
> the body's intrinsic operating voltages (across nerve
> membranes) are on the order of 50kV/meter. ORDERS of magnitude
> above what you would get from typical external EM fields.
> Muscles also produce 100's of millivolts, again over tiny
> scales, so you have low kV/meter all the time (remember that
> your heart is beating all the time and you do have to breath).

That argument is totally unconvincing to me. I could counter that by
saying a television set has 25 kV, yet it is able to receive very small RF
(and IR) signals.

There are plenty of studies that say there's no link between smoking and
cancer - it depends who funds the study.

Let the public panic - maybe they'll get some exercise :)

Cheerful regards,

Bob

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listservEraseMEspam.....mitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@200140 by William Chops Westfield

face picon face
On Aug 2, 2004, at 10:17 AM, Robert B. wrote:

> The way I understand it, any escaped microwaves would only heat me up.

Ah, you haven't read either Brunner's "The Sheep Look up", or Varley's
"Press Enter", then.  Nice horrific scenes involving microwaves that'll
change the way you look at ovens, regardless of their level of
technical accuracy...

Shudder
BillW

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email EraseMElistservspammitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@211403 by Russell McMahon

face
flavicon
face
> What always amuses me about the 'panicked public' is that
> the body's intrinsic operating voltages (across nerve
> membranes) are on the order of 50kV/meter. ORDERS of magnitude
> above what you would get from typical external EM fields.
> Muscles also produce 100's of millivolts, again over tiny
> scales, so you have low kV/meter all the time (remember that
> your heart is beating all the time and you do have to breath).

etc
All good stuff.
But prudent avoidance is still prudent IMHO.
Don't have to destroy one's life over such things.
But much of post disaster assessment is working out how what couldn't
possibly have happened happened, and how it could have been foreseen, and
how not to let it happen again. Even though it will.

So far the US is two Shuttles down, can see with blinding clarity in
hindsight what was going wrong, but walked into both disasters blithely.


       Russell McMahon

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email RemoveMElistservEraseMEspamEraseMEmitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@211403 by Russell McMahon

face
flavicon
face
What part of "cooked food" don't you understand ? :-)

> The way I understand it, any escaped microwaves would only heat me up.  I
> don't ever feel warmer when the microwave is running, therefore I am not
> very concerned.

They'd wlecome you with open arms as a worker at any asbestos factory :-)

The debate re the effects of non-ionising radiation is a century or so long.
Correlation of cancer levels with various related occupations can be shown.
Standards vary between countries BUT your microwave will happily exceed them
all :-). Quit apart from the possible obscure phsyilogical effects which may
or may not exist, a good dose of microwaves can cause cataracts - localised
burning. I suspect you would like to avoid this happening in your eyes and
brain at least. Brain hasn't got too much water in the outer cladding but
there are lots of nice resonant molecules just under that hard shell. Eyes
are nicely full of water from surface in. The 2400 GHz band is an ISM band
AND is used for microwave heating precisely because water has an absorbtion
line there.

> The oven's rating is 800W, 2450MHz.  Even if all that
> radiation escaped in a concentrated beam, it would still be far below many
> commercial microwave transmitters.

Below many, yes. Above many in watts/m^2, yes. How concentrated the beam is
from the nice slot radiator you may have made by dropping it is unknown. A
slot radiator is an entirely useful form of antenna. How good your one is is
of course unknown. Don't make its day by finding out.

> I've heard stories of tech's sitting
> near the microwave transmitter beams to keep warm in the winter,

Many "Darwin Award" stories are untrue.
Many true Darwin Award stories are unbelievably unbelievable.
It's hard to imagine anyone doing the really really stupid things that
people really do.

> so I'm
> still having trouble believing a little microwave radiation leakage could
> actually do any damage.

YMWPV.

> I'm certainly no expert, and if you have a source indicating that it is
> actually dangerous I'd love to read it.  I'm sure there are some HAMs on
> this list (apparently you, Dave?) who know all about microwave radiation
and
> might have a link or two so I could learn about it too.

The web is utterly full of RF radiation hazrad warnings. The closest one to
you will probably be printed on a lable on your microwave. Every new
microwave I came with came with a warning that said - "Don't Do IT !!" or
similar.

What part of cooked food don't you understand ? :-)

> So far in my research I've discovered that the FDA advocates less than
> 2mW/cm2 leakage for new ovens.  This is apparently to avoid interfering
with
> communications devices rather than protect the biological species using
the
> microwave.

One of the international levels for human exposure is 10 mW/cm^2.
How good is your slot radiator?

Take 100 cc (3 ounces) of water in  aplastic bag.
Hang bag on a string across known leakage area.
Run over for several minutes.
Test water temperature.
Regardless of result, throw over away.



       Russell McMahon

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email RemoveMElistservspam_OUTspamKILLspammitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@214556 by Robert Ussery

flavicon
face
>-----Original Message-----
>From: pic microcontroller discussion list [RemoveMEPICLISTTakeThisOuTspamspamMITVMA.MIT.EDU]
>On Behalf Of Russell McMahon

>YMWPV.

Wow! That's an obscure one... I googled for it, and only came up with 10
results, none of which had a definition of it. I checked all the usual lingo
dictionaries, and none of them had it...

What's it mean? More importantly, perhaps, where'd you pick it up?

I can get "You may want p-something v-something", but I can't figure it out.

TTYL!

- Robert

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email EraseMElistservspamspamspamBeGonemitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@215352 by Robert B.

flavicon
face
I read it as "your mileage will probably vary", but on second thought its
probably "your mother would probably vomit".


----- Original Message -----
From: "Robert Ussery" <RemoveMEuavscienceKILLspamspamFRII.COM>
To: <PICLISTSTOPspamspamspam_OUTMITVMA.MIT.EDU>
Sent: Monday, August 02, 2004 9:42 PM
Subject: Re: [OT:] Microwave ovens was WIFI Waveguide antenna


> >{Original Message removed}

2004\08\02@215808 by Robert Rolf

picon face
Russell McMahon wrote:

> What part of "cooked food" don't you understand ? :-)

It's only 'cooked' if you denature the proteins. That requires
temperatures over 42C.

>>The way I understand it, any escaped microwaves would only heat me up.  I
>>don't ever feel warmer when the microwave is running, therefore I am not
>>very concerned.

> They'd wlecome you with open arms as a worker at any asbestos factory :-)

And kilowatts of RF energy is used in diathermy treatments in hospital
physiotheraphy wards. (deep heating of injured tissues increase blood
flow and healing).

> all :-). Quit apart from the possible obscure phsyilogical effects which may
> or may not exist, a good dose of microwaves can cause cataracts - localised
> burning.

Yep. And since the cornea's and lens have no nerves, you'd never
know you were cooking until you blinked and your eyelids felt the
surface heat.

{Quote hidden}

Don't forget to have a 'control' bag of water to account
for room temperature heating. i.e. same bag, same start temp,
same place, same time, but WITHOUT powering the over.

http://www.gallawa.com/microtech/output.html

Over the years manufacturers have used several different methods to rate
the output wattage of microwave ovens. First, there was the  traditional
 method. Then, in 1989-90 came the  JIS  (Japanese Industrial
Standard). Using the JIS method, ovens rated at 700 watts using the
traditional  method became 750-watt ovens. In 1990-91 the industry
changed to the international  IEC-705  standard. This pushed the wattage
ratings even higher. For example, models rated at 700  traditional
watts were instantly turned into 800-watt ovens using the IEC-705 formula.

   1.   Procedure:   Pour exactly 1000 mL (1 Liter) of cool tap water
into the container. Using the thermometer, stir the water, then measure
and record the temperature. For accurate results the water should be
about 60 degrees F (20 degrees C).
   2. Place the container on the center of the oven cooking shelf (do
not leave the thermometer in the container and remove any metal racks),
and heat the water (at full power) for 63 seconds. Use the second hand
of a watch, not the oven timer. [OLD OLD ovens]
   3. After the heating time is completed, immediately remove the
container, stir the water, re-measure and record the temperature of the
heated water.
   4. Subtract the starting water temperature (step 2) from the ending
water temperature (step 3) to obtain the temperature rise.
   5.
      To determine the output power in watts, multiply the total
temperature rise by a factor of:
          38.75 , if you're using a Fahrenheit thermometer;
          70 , if you're using a centigrade thermometer.

{some other sites say multiply by 35 for delta in F.
Someone want to derive the equations from first principles?}

Robert

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email spamBeGonelistservSTOPspamspamEraseMEmitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@220223 by Robert Ussery

flavicon
face
>-----Original Message-----
>From: pic microcontroller discussion list [KILLspamPICLISTspamBeGonespamMITVMA.MIT.EDU]
>On Behalf Of Robert B.


>I read it as "your mileage will probably vary", but on second thought its
>probably "your mother would probably vomit".

Gotcha... Given the original context, I'm sure you're right.

Your mother probably would vomit if she could see how you live, eating only
microwave cooked food, tanning with a broken microwave oven, etc.*
<grin>

Darn it, Russell, you're talking over my head, again.

But then again, YMWPV.

- Robert






* for those on this list with no sense of humor, this is sarcasm. Just
CYA-ing (or would that be CMA-ing?)

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email EraseMElistservspamEraseMEmitvma.mit.edu with SET PICList DIGEST in the body

2004\08\02@222143 by Robert B.

flavicon
face
FWIW I'm planning on ditching the death-ray, just because theres no sense in
taking any easily avoidable risk.  But...  I'm still not convinced there's
much danger to be had in my particular unit.  I tried the water-bag test,
and it didn't feel any warmer than when the test started.  Waving one of
those tiny little fluorescent camping-lantern tubes around the edge it was
dropped on reveals a small area in which the tube is lit ever-so-dimly,
unobservable except in the dark, and even then you have to look closely.  No
heat is sensed (with my hand) around any portion of the microwave while its
running, and it still cooks food as fast as it ever did.  Moreover, I don't
ever run it empty, so the majority of the death-ray is absorbed by the food
I'm about to eat.

After a century or so of debate, I'm of the opinion that firm facts and
studies would have clearly demonstrated any long-term harmful effects of
non-ionizing radiation.  Aside from cooking your corneas (which happens
fairly quickly), I haven't seen anything more than a statistical blip in any
of the related medical studies.  Everybody "warns" against it, but nobody
has any significant evidence that it actually does long term harm.  IMHO its
a non-problem.  Sort of like people freaking out about a bit of
ionizing-radiation every now and then.

The warning labels all read like death-ray radiation warning labels should,
but thats certainly more for liability than anything else.  I hardly take
warning labels to be an objective source of scientific fact, though they
should of course (at the very least) be carefully considered before ignoring
them ;)

Moreover, all the "harmful effects" I've encountered in any study I've read
from non-ionizing radiation were more or less instantaneous.  IE if your
corneas are gonna be cooked you'll find out real quick, as opposed to
cumulatively over weeks, months or years.

But yes, I'll cave to safety and get rid of it.  But when I dispose of it,
its gonna be a fantastic explosion for sure.  None of this just smashing it
with a brick stuff.

{Original Message removed}

2004\08\02@224046 by Russell McMahon

face
flavicon
face
> >YMWPV.

YMMV       = Your mileage may vary
YMWPV    = Your mileage will probably vary :-)



       RM        = Russell McMahon

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email @spam@listserv@spam@spamspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

2004\08\03@015418 by Roland

flavicon
face
>I work in Neuroscience, and have reviewed the literature because
>of the RF excited implanted stimulators we use for rehab. FES.
>
>There are also TNS (Transcranial Neural Stimulators) which create
>kilo Tesla fields to directly stimulate deep brain regions.
>None of the 10's of thousands of patients exposed to these
>fields has ever been reported as having come down with brain
>cancer or related diseases, and given the sample space and EM
>strength, this SHOULD have happened if there were a causal
>relationship.

mmm, science again. This is tantamount to using a cattle probe to stimulate
your PC. Also falls in with the concept of frontal lobotomies as a 'cure'.

The human body is fantastically resilient to external influence, because of
it's self-healing properties, but it is also very sensitive. You won't
catch me near a MRI machine, let alone a doctor.
OK, doctors are useful, but it's mostly professional butchery.

Regards
Roland Jollivet

--
http://www.piclist.com hint: To leave the PICList
spamBeGonepiclist-unsubscribe-requestspamKILLspammitvma.mit.edu

2004\08\03@034152 by Alan B. Pearce

face picon face
>Heat up a screwdriver and stick it on this magnet
>and when it cools off it is a magnetic screwdriver.

You don't need to heat it, just wipe it across the pole faces a couple of
times.

--
http://www.piclist.com hint: To leave the PICList
.....piclist-unsubscribe-requestspam_OUTspammitvma.mit.edu

2004\08\03@043508 by Nate Duehr

face
flavicon
face
Robert Rolf wrote:
>    3. After the heating time is completed, immediately remove the
> container, stir the water, re-measure and record the temperature of the
> heated water.

In 63 seconds this should not happen, but be forewarned that in older
ovens without carousels, water in a container sitting very still can
become superheated in a microwave oven.  Upon disruption by some object
(thermometer in this case) the superheated (above boiling point but not
boiling) water can and will explode out of the container as it all
instantaneously boils over, flashing to steam and covering the
unsuspecting "scientist" with boiling water.

Carousels and ovens that naturally vibrate quite a bit are, of course,
less prone to this type of accident.  Ovens that leave the food very
still in a single location that heat a container of liquid very evenly
are more likely to do this.

--
Nate Duehr, TakeThisOuTnate.....spamTakeThisOuTnatetech.com

--
http://www.piclist.com hint: To leave the PICList
TakeThisOuTpiclist-unsubscribe-requestKILLspamspamspammitvma.mit.edu

2004\08\03@060020 by Russell McMahon

face
flavicon
face
> water in a container sitting very still can
> become superheated in a microwave oven.  Upon disruption by some object
> (thermometer in this case) the superheated (above boiling point but not
> boiling) water can and will explode out of the container as it all
> instantaneously boils over, flashing to steam and covering the
> unsuspecting "scientist" with boiling water.

This is even more liable to occur if you boil the water, leave it in the
microwave oven to cool somewhat and then boil  again. The first heating
removes much of the dissolved air which otherwise acts as nucleation points
for localised boiling. Water and steam may both exist at 'boiling point" -
typically 100 C. Steam takes more energy BUT you can add energy to the water
without a unit mass having enough energy to convert to steam.

If none changes then all will stay the same (obviously enough) - for a
while. If a little changes it may disturb the  surrounding water enough to
cause it to take up any extra energy available and make the phase change.
While undisturbed the heated water starts to transition between solid state
and gaseous state but has no localised points at which this may occur
preferentially. Finally something disturbs it enough to trigger a chain
reaction. This provocation can be essentially spontaneous or may be caused
by stirring or carrying. I believe that a major part of the liquid can
decide to leave rapidly.

The fact that the microwave energy is applied much more evenly to the vessel
also "helps". With normal bottom up thermal heating the water is circulated
by convection currents and this disturbance helps to destroy the low
disturbance environment needed.

I have actually tried to induce this effect several times without success -
was spur of the moment effort and not consistently approached.

HOWEVER - I saw it happen to someone else about 2 weeks ago in a motorcamp
kitchen. The lady was about to make coffee when most of her cup of
microwaved water literally exploded out of the cup.



       RM

--
http://www.piclist.com hint: To leave the PICList
.....piclist-unsubscribe-requestspamRemoveMEmitvma.mit.edu

2004\08\03@143106 by Gaston Gagnon

face
flavicon
face
Nate Duehr wrote:
<...>
> In 63 seconds this should not happen, but be forewarned that in older
> ovens without carousels, water in a container sitting very still can
> become superheated in a microwave oven.  Upon disruption by some object
> (thermometer in this case) the superheated (above boiling point but not
> boiling) water can and will explode out of the container as it all
> instantaneously boils over, flashing to steam and covering the
> unsuspecting "scientist" with boiling water.

Look at the videos. Very impressive ... scary
http://apache.airnet.com.au/~fastinfo/microwave/videos/watervideos.html

Gaston Gagnon

--
http://www.piclist.com hint: To leave the PICList
RemoveMEpiclist-unsubscribe-requestspamspamBeGonemitvma.mit.edu

2004\08\03@233711 by Rich

picon face
It is my understanding that the two hydrogen atoms in the H20 water molecule
are at an angle of approximately 105 degrees (because the hydrogen atoms
must share at a resonance that results in such an angle.  The 2450 MHz
introduces energy into the H20 molecule because the molecule can accept the
energy due to is structure, and causes the two hydrogen atoms to be
displaced (kind of rocks them back and forth,so to speak).  It is this
regular periodic displacement which resonates that causes the water to boil
(i.e., by friction).  Ideally, the 2450 MHz will only heat the water
molecule because the water molecule can absorb the energy, whereas plastic
molecules, and may others, cannot.  Please let me know if this explanation
is unsatisfactory, or not technical enough.



{Original Message removed}

2004\08\04@011048 by Russell McMahon

face
flavicon
face
> molecules, and may others, cannot.  Please let me know if this explanation
> is unsatisfactory, or not technical enough.

Worth noting that all sorts of other non water containing materials are
variably absorbative (?) of RF at that frequency. Some plastic (very
possibly due to Hydrogen bonds also) are quite affected while others not at
all.

The classic way to get absorption is to provide a shorted turn of some sort
with some resistive loss to dissipate the energy. I've seen the top of a
glass coffee pot melted when it was microwaved (at my unwitting
recommendation :-)  ) - because there was a metal ring of about 4": ID
inside the plastic handle - who would have thought ? ;-). I was not flavour
of the week.

Plates with gold decoration around the edges also form a shorted turn and
put on an enthusiastic & impressive display of energy dissipation until the
gold gets tired and leaves.

Controlled absorption is used in eg browning plates. A standard uWave oven
may also be used to melt metal if a suitably dissipative container is used
to hold the metal.

       http://home.c2i.net/metaphor/mvpage.html

       http://home.c2i.net/metaphor/



       RM

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2004\08\04@015445 by Jinx

face picon face
> gold gets tired and leaves.

Oh, haha. Gold leaf

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2004\08\05@002813 by Rich

picon face
Any screwdriver made with ferrous material can become a magnetic screwdriver
by simply rubbing the shaft back and forth against a strong enough permanent
magnet. The magnetic field re-orders the position of the magnetic dipoles in
the ferrous material in such a way that they line up in the same direction.


{Original Message removed}

2004\08\05@003227 by Rich

picon face
You must carefully construct a research design that posits your hypothesis
and tests the null hypothesis.  Use a temperature measurement device.  There
are non-contact optical pyrometers that are quite accurate.  ALL RF IS
DANGEROUS, but it is most dangerous when one gets careless or comfortable.


{Original Message removed}

2004\08\05@003642 by Rich

picon face
Also, a special parabolic antenna design can focus the uWave at a specific
(x,y,z) point.  The energy can also be made to concentrate at that point.
These techniques are also used in optics.  You can get seriously hurt by
attempting experiments you are not ready for.


{Original Message removed}

2004\08\05@063242 by Howard Winter

face
flavicon
picon face
On Mon, 2 Aug 2004 13:17:55 -0400, Robert B. wrote:

> The way I understand it, any escaped microwaves would only heat me up.

Try holding a 5W 12V bulb between your fingers while it's running for a few minutes and see how comfortable
"only heating up" feels!

> I don't ever feel warmer when the microwave is running, therefore I am not
> very concerned.

When I got my first mobile phone (a Nokia that later was known as one of the most powerful RF radiators) I
found that if I used it against my right hear, I got a pain in my right eye.  It didn't feel warm, it hurt!
Consequently I held it to my left ear (for some reason that felt OK) but I also used it as little and for as
short a time as possible.  I have no idea if it did me any harm, but reducing the risk seemed like a good
idea!  In hindsight perhaps I should have changed the phone for one that didn't hurt earlier than I did, but
you know what they say about hindsight!

To quote the National Radiological Protection Board (the UK's watchdog on this sort of thing): "the difference
between exposure to infra-red frequencies (radiant heat) and microwaves is that the former produces surface
heating while the latter is absorbed within the body tissue thus raising its bulk temperature. Thermal damage
has been shown to occur at radiation intensities of 100 mW/cm 2 and above."  This is from:
http://www.hse.gov.uk/lau/lacs/60-3.htm

The last time I heard the legal "safe limit" in the UK was 10mW/cm2, although I believe proposed European
regulations are to reduce this, and may have already done so.

> The oven's rating is 800W, 2450MHz.  Even if all that
> radiation escaped in a concentrated beam, it would still be far below many
> commercial microwave transmitters.

I think you're wrong.  When the firm I used to work for needed a microwave communications link, it was limited
to 10mW.

> I've heard stories of tech's sitting
> near the microwave transmitter beams to keep warm in the winter, so I'm
> still having trouble believing a little microwave radiation leakage could
> actually do any damage.

Have you heard ot the Darwin Awards?  Just because people do things it doesn't mean it's safe!  :-)  When I
was a kid there were machines in shoe shops where you could put your feet into slots in the bottom, and look
down into the top and see your feet inside your shoes - they were always-running X-ray machines.  My mother
told me to stay away from them because they "weren't good for you" - so I did, and I'm rather glad that my
mother's intuition was ahead of scientific thinking at the time!

Cheers,


Howard Winter
St.Albans, England

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@063242 by Howard Winter

face
flavicon
picon face
Lawrence,

On Mon, 2 Aug 2004 13:09:20 -0500, Lawrence Lile wrote:

> Don't bash in the door - get inside the thing and take
the magnet out of it.

How big *is* this microwave?  :-)))

Cheers,


Howard Winter
St.Albans, England

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@065355 by Howard Winter

face
flavicon
picon face
Robert,

On Mon, 2 Aug 2004 15:52:29 -0600, Robert Rolf wrote:

> What always amuses me about the 'panicked public' is that
> the body's intrinsic operating voltages (across nerve
> membranes) are on the order of 50kV/meter. ORDERS of magnitude
> above what you would get from typical external EM fields.
> Muscles also produce 100's of millivolts, again over tiny
> scales, so you have low kV/meter all the time (remember that
> your heart is beating all the time and you do have to breath).

And yet 35mA is regarded as the safe limit for an electric shock...

> External EM fields are down in the noise compared to what
> body cells are exposed to on a continuous basis.
> And the body electrolytes are highly conductive, highly
> attenuating higher RF frequencies with depth.

"Attenuating" must mean "absorbing", unless you know another way to get rid of energy?

> And if the 'radiation' is non-ionizing, the worst that can
> happen is that you get warmed up a bit, which is not a problem
> since your blood carries away the heat.

On a major scale, yes, but if the energy concentration is high enough om a small area you may get local
boiling which would destroy cells.

>The only body part
> that is not protected by this cooling process is the lens and
> cornea of the eye. Cook those (42C+) and you DO have a problem,
> but nothing fatal.

I don't regard going blind as something I'd like to happen, even if it's "non fatal"!

> I work in Neuroscience, and have reviewed the literature because
> of the RF excited implanted stimulators we use for rehab. FES.
>
> There are also TNS (Transcranial Neural Stimulators) which create
> kilo Tesla fields to directly stimulate deep brain regions.

I was never much good at magnetism, which I believe falls off rapidly with distance anyway (I don't think you
can "transmit" magnetic energy - I'm more concerned about the RF "electric" side of it.

> None of the 10's of thousands of patients exposed to these
> fields has ever been reported as having come down with brain
> cancer or related diseases, and given the sample space and EM
> strength, this SHOULD have happened if there were a causal
> relationship.

There has been a study in Poland which correlates microwave exposure of military personnel with cancers - see:
http://www.feb.se/EMFguru/Current-Messages/emf-cancer.html

> And lets not forget the statistics of TENS OF MILLIONS of
> cellular phone users, and their NOT having brain cancers
> at anything above random rates.

Worldwide it's hundreds of millions, but mobile phones haven't been around very long, and cancer takes time to
happen - nobody (not even the anti-RF evangelists) says that using a mobile phone today will kill you
tomorrow.  Both my parents smoked from their teens - my father survived to age 67 before it killed him, my
mother to 51.  I'm 50, and *really* glad that smoking never seemed like a good idea to me!  During WWII Brits
(at least) were encouranged to smoke by the government, who thought that it would produce a calmer population,
more able to cope with the stresses of wartime...

Cheers,

Howard Winter
St.Albans, England

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@071922 by Howard Winter

face
flavicon
picon face
Robert,

On Mon, 2 Aug 2004 19:51:02 -0600, Robert Rolf wrote:

> Over the years manufacturers have used several
different methods to rate
> the output wattage of microwave ovens.
>...<

Thanks for the rating-procedure - I only had a
thermometer with whole-degree C reading, and it showed
an 8C rise, giving 560W plus or minus 70W.  It's an old
microwave and I don't know what its rating was sold as,
but I know the real figure now!

Cheers,


Howard Winter
St.Albans, England

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@073418 by Howard Winter

face
flavicon
picon face
Nate,

On Tue, 3 Aug 2004 02:34:39 -0600, Nate Duehr wrote:

> In 63 seconds this should not happen, but be forewarned that in older
> ovens without carousels, water in a container sitting very still can
> become superheated in a microwave oven.  Upon disruption by some object
> (thermometer in this case) the superheated (above boiling point but not
> boiling) water can and will explode out of the container as it all
> instantaneously boils over, flashing to steam and covering the
> unsuspecting "scientist" with boiling water.

This can happen (and has) with reheating cups of coffee and the like, but in this case we're talking about a
litre of water, and the maths show that to heat it from 20C to 100C in the 63secs you'd need 5600W and as far
as I know there are no kitchen microwaves that powerful!  (Assuming 100% efficiency that would need a 50A
supply in the US, a 24A supply in Europe, and I believe that's pretty unusual for domestic sockets :-)

Cheers,

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@073624 by Howard Winter

face
flavicon
picon face
Russell,

On Tue, 3 Aug 2004 21:47:39 +1200, Russell McMahon
wrote:

> While undisturbed the heated water starts to
transition between solid state
> and gaseous state

I don't think you meant "solid"  ;-)

Cheers,


Howard Winter
St.Albans, England

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@075741 by Russell McMahon

face
flavicon
face
> > While undisturbed the heated water starts to
> transition between solid state
> > and gaseous state
>
> I don't think you meant "solid"  ;-)


True.
Such an arrangement would be sublime :-)
(Now with a little adjustment of the pressure ... )


       RM

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@082932 by Lawrence Lile

flavicon
face
>Just because people do things it
> doesn't mean it's safe!  :-)  When I
> was a kid there were machines in shoe shops where you could put your
feet
> into slots in the bottom, and look
> down into the top and see your feet inside your shoes - they were
always-
> running X-ray machines.  My mother
> told me to stay away from them because they "weren't good for you" -
so I
> did, and I'm rather glad that my
> mother's intuition was ahead of scientific thinking at the time!
>

Stunts like this are probably why my father had leukemia at 35.  He was
in medical school right after WWII, when "radiation" and "Hazard" were
never used in the same sentence. Had a lot of access to X ray equipment.


-- Lawrence Lile, P.E.
Electrical and Electronic Solutions
Project Solutions Companies
http://www.projsolco.com

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@083346 by Lawrence Lile

flavicon
face
I have tried to make mag screwdrivers with the rubbing trick, however
heating them and letting them cool while stuck to a strong magnet seems
to make a better and longer lasting magnet out of them.  I am sure there
are plenty of other ways.



-- Lawrence Lile, P.E.
Electrical and Electronic Solutions
Project Solutions Companies
http://www.projsolco.com

> {Original Message removed}

2004\08\05@084632 by Howard Winter

face
flavicon
picon face
Lawrence,

On Thu, 5 Aug 2004 07:28:41 -0500, Lawrence Lile wrote:

> I have tried to make mag screwdrivers with the rubbing trick, however
> heating them and letting them cool while stuck to a strong magnet seems
> to make a better and longer lasting magnet out of them.

But it's a good idea if you can thermally insulate it from the magnet - heating a magnet is a really good way
to weaken or destroy it (I've just realised I remember that from an exam question at school about 35 years ago
:-)

Cheers,


Howard Winter
St.Albans, England

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@085250 by Robert B.

flavicon
face
How much are you heating them?  Hopefully not enough to destroy the temper,
which is done surprisingly easily.  Temperatures as low as 150C are enough
to affect the grain structure of steels.

{Original Message removed}

2004\08\05@094822 by M. Adam Davis

flavicon
face
Howard Winter wrote:

>And yet 35mA is regarded as the safe limit for an electric shock...
>
>
>
>
Everytime I see this, " XXmA is the limit", I think back to all the
different opinions.  The lowest I've seen is 10mA, but generally the
only reason these shocks are not safe is because they /might/ disrupt
the pace of the heartbest.  Thus they all pretty much have to be through
the heart (hand to hand, hand to foot, head to anything, etc).

Of course this has little to do with the voltage applied - you can have
kV of potential across your body and only uA of current, and under 100V
with over 100mA of current.  You could have 1A going from your thumb to
your forefinger without killing yourself, or foot to foot, though I
imagine it would be pretty painful just before you blacked out. :-)

Not only is the current a 'soft' variable, but timing is also critical,
and voltage waveform has a big effect.  It has to be applied at the
right time to cause the heart to fibrillate (it's very rare, I
understand, for the heart to stop beating completely - usually it just
beats ineffectively, which has the same end result).  AC is sometimes
not as bad as DC because it tries to travel along the outside of the
conductor, and little current may go through the heart.

Doesn't mean I like to touch the electric horse fence, though.  Worst
way to see if one is working - disconnect both terminals, place one hand
on one terminal and one hand on the other.  Feels like a 20 pound sledge
hammer right in the chest - had to sit down for 30 minutes after that
stupidity, and can only hope it didn't cause any sort of permanent
damage that will come back to haunt me.

-Adam

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@102314 by Howard Winter

face
flavicon
picon face
On Thu, 5 Aug 2004 09:48:05 -0400, M. Adam Davis wrote:

> Howard Winter wrote:
>
> >And yet 35mA is regarded as the safe limit for an electric shock...
> >
> Everytime I see this, " XXmA is the limit", I think back to all the
> different opinions.

Yes, but you have to have a figure to design an RCCD (safety device to break the circuit when some of the
current gets away) and 35mA / 35mS is easy to remember!  :-)

My point was that quoting electric field density is misleading since that is only one measurement of the many
possiblilities.  There's much more heat-energy in a bath of warm water than in a red-hot nail, but I know
which one I'd rather touch!

> The lowest I've seen is 10mA, but generally the
> only reason these shocks are not safe is because they /might/ disrupt
> the pace of the heartbest.

They can also cause physical damage, internal burns, cell disruption, and disruption of nerves' ability to
function.

> Thus they all pretty much have to be through
> the heart (hand to hand, hand to foot, head to anything, etc).

It's not easy to decide where the current will travel before you get the shock (presumably you'd decide not to
get it at all, otherwise) although the old "keep one hand in your pocket" rule for working on high voltage
gear is a Good Thing.  But the designer of safety equipment has to assume the worst.

> Of course this has little to do with the voltage applied - you can have
> kV of potential across your body and only uA of current,

Hurts like hell though!  A shock from a spark plug really does make you jump, but doesn't do damage unless it
causes you to pull your hand away into something hot or rotating.  Many years ago I knew someone who "didn't
feel" the shock from a spark plug - I have no idea how this can happen - and he would have one finger on the
plug-cap, and a finger on the other hand producing sparks to the bodywork, without even flinching.  If people
asked if it hurt, he would get hold of their hand and repeat the procedure... I never fell for *that* one!

> and under 100V
> with over 100mA of current.  You could have 1A going from your thumb to
> your forefinger without killing yourself, or foot to foot, though I
> imagine it would be pretty painful just before you blacked out. :-)

Quite!  That's why you should stand with your feet together if you're outside during a thunderstorm - or run
like mad to get inside!  :-)  But the differential voltage across the ground has been known to kill cattle,
since their front and back legs are a long away apart and their heart tends to be on the way between.

I once heard the saying:  "It's the volts that jolts, it's the mill's that kills".  The grammar is rubbish but
it's technically correct, and memorable!

>...<
>
> Doesn't mean I like to touch the electric horse fence, though.  Worst
> way to see if one is working - disconnect both terminals, place one hand
> on one terminal and one hand on the other.  Feels like a 20 pound sledge
> hammer right in the chest - had to sit down for 30 minutes after that
> stupidity, and can only hope it didn't cause any sort of permanent
> damage that will come back to haunt me.

The advice in cases like this is to go to a doctor/hospital and get checked out.  People have been known to
survive a shock at the time, only to die a day or two later due to creeping failure of the heart muscle,
started by the shock.  I know it's easy to say that sitting here, but it's worth remembering in future, and
yes, I've had a mains shock (240V 50Hz here) that left me feeling dazed and "abent-minded" for some time
afterwards, and I didn't see anyone about it either.  But I will next time!

Cheers,


Howard Winter
St.Albans, England

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@115414 by Robert Rolf

picon face
Rich wrote:
> You must carefully construct a research design that posits your hypothesis
> and tests the null hypothesis.  Use a temperature measurement device.  There
> are non-contact optical pyrometers that are quite accurate.  ALL RF IS
> DANGEROUS, but it is most dangerous when one gets careless or comfortable.

So you don't use cell phones or Wi-Fi or Bluetooth or cordless
phones or ANY form of RF receiver?? What about microwave ovens?

How can you say "ALL RF IS DANGEROUS" when we live in a sea
of low power RF, yet we're still alive?
I can also kill you with pure distilled water.

Hyperbole will get your arguments quickly dismissed.
Perhaps you meant
'High Power' RF CAN BE dangerous if not treated with respect.

R

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@141229 by John Ferrell

face picon face
> Doesn't mean I like to touch the electric horse fence, though.  Worst
> way to see if one is working - disconnect both terminals, place one hand
> on one terminal and one hand on the other.  Feels like a 20 pound sledge
> hammer right in the chest - had to sit down for 30 minutes after that
> stupidity, and can only hope it didn't cause any sort of permanent
> damage that will come back to haunt me.

Not a good idea to Pee on one either!

John Ferrell
http://DixieNC.US

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@160313 by Robert Rolf

picon face
John Ferrell wrote:

>>Doesn't mean I like to touch the electric horse fence, though.  Worst
>>way to see if one is working - disconnect both terminals, place one hand
>>on one terminal and one hand on the other.  Feels like a 20 pound sledge
>>hammer right in the chest - had to sit down for 30 minutes after that
>>stupidity, and can only hope it didn't cause any sort of permanent
>>damage that will come back to haunt me.
>
>
> Not a good idea to Pee on one either!

"Mythbusters" (a TV show on Discovery Channel Can)
proved that you need not worry about this.
Your pee stream always breaks up into droplets by
time it could hit the fence (or third rail).

You basically need a garden hose to get enough volume to
have a continuous stream.

R

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@180010 by Lawrence Lile

flavicon
face
That is not what my friend said when I watched him try it (he was 8 and
stupid, I was 6 and stupid but not that stupid).  Maybe he was closer to
the ground, but it gave him quite a wallop.
> > Not a good idea to Pee on one either!
>
> "Mythbusters" (a TV show on Discovery Channel Can)
> proved that you need not worry about this.
> Your pee stream always breaks up into droplets by
> time it could hit the fence (or third rail).
>
> You basically need a garden hose to get enough volume to
> have a continuous stream.
>
--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@182742 by David VanHorn

flavicon
face
At 04:56 PM 8/5/2004, Lawrence Lile wrote:

>That is not what my friend said when I watched him try it (he was 8 and
>stupid, I was 6 and stupid but not that stupid).  Maybe he was closer to
>the ground, but it gave him quite a wallop.

What a brilliant example of the pitfalls of simulation vs prototyping. :)

(bonus points for getting HIM to try it :)

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@230429 by Rich

picon face
----- Original Message -----
From: "Robert Rolf" <spamBeGoneRobert.Rolf@spam@spamspam_OUTUALBERTA.CA>
To: <TakeThisOuTPICLISTspamspamMITVMA.MIT.EDU>
Sent: Thursday, August 05, 2004 11:43 AM
Subject: Re: [OT:] Microwave ovens was WIFI Waveguide antenna


> Rich wrote:
> > You must carefully construct a research design that posits your
hypothesis
> > and tests the null hypothesis.  Use a temperature measurement device.
There
> > are non-contact optical pyrometers that are quite accurate.  ALL RF IS
> > DANGEROUS, but it is most dangerous when one gets careless or
comfortable.
>
> So you don't use cell phones or Wi-Fi or Bluetooth or cordless
> phones or ANY form of RF receiver?? What about microwave ovens?
>
> How can you say "ALL RF IS DANGEROUS" when we live in a sea
> of low power RF, yet we're still alive?

Rich answered:

I agree that the wording is too general.  But all RF exposure is potentially
dangerous and some is absolutely dangerous.  I know of a fellow that used to
tune antennas for radio stations.  He would call the control room and have
them kill the power before he left the tower.  One time the power was left
on and as he jumped from the concrete base to the ground a RF arc burned him
to death, presumably before he hit ground.  I, myself, have had several
painful RF burns from working on low power transmitters.  They are quite
painful and seem to burn from the inside out.  (Of course I did not prove
that, but it felt like it.)  My point was really that one must exercise
great caution when working with RF, just as when working with high voltage.
I once saw a dude short out some capacitors while I hollered "NO Don't DO
THAT" to him.  The capacitors exploded and the dude was hurt pretty bad and
of courrse the screw driver was melted.   I have learned to respect the
dangers involved in science.  Madam Curie was unfortunately unaware of the
hazards of radiation, the inventor of morphine died from addiction and the
stories abound.

I know the axiom the the negation of a universal quantifier is an
existential qualifier, so if I was generalizing hastily, I accept that
criticism.  But I am comfortable with the phrase all RF is "potentially"
dangerous.

While we do know that radiation intensity decreases as a square function
with respect to distance, we have not yet established a golden standard for
an individual of a given mass, although there are some recommendations.

> I can also kill you with pure distilled water.

Rich replied:
Anyone can die from drinking an excessive amount of water.  So, what does
that prove about radiation?
>
> Hyperbole will get your arguments quickly dismissed.
> Perhaps you meant


> 'High Power' RF CAN BE dangerous if not treated with respect.

Replied again:
If I may say so, LOW POWER RF CAN BE DANGEROUS if not treated with respect
or proper management.  Furthermore, the RF frequency is a definite factor,
besides power.

Rich also says:
Thank you for the discussion.  I find such discussions informative and
generally speaking, useful.
>
> R
>
> --
> http://www.piclist.com hint: The list server can filter out subtopics
> (like ads or off topics) for you. See http://www.piclist.com/#topics
>

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\05@235739 by Russell McMahon

face
flavicon
face
> > How can you say "ALL RF IS DANGEROUS" when we live in a sea
> > of low power RF, yet we're still alive?

> I agree that the wording is too general.  But all RF exposure is
potentially
> dangerous and some is absolutely dangerous.

Prudent avoidance.
Practice prudent avoidance.
Chorus:    Prudent ......

Use solder, petrol, diesel (if you must), RF, DC, AC, PICs ;-), alcohol,
food, ....

Be aware that all are dangerous to an unknown and variable extent.
Enjoy life, have fun, don't be paranoid, do be aware that real dangers exist
all over, ventilate work places, stay away from diesels (produce amongst the
most cancerous particles known to man), keep the mains powered alarm clock
well away from your head when sleeping,  do do an EM sweep of your house
once every few years, don't live under hv power lines or within a few
lots/sections thereof. look both ways when crossing, do not spindle staple
fold or mutilate, drink alcohol sparingly, keep one hand in pocket, the
brighter the plant colour the better it is for you (usually)(don't eat too
much), don't sleep too much or too little (however long that may be), too
fat will kill you quicker, too thin will too, avoid very high or very low
anything diets, you need some saturated fats to keep your ldl:hdl ratio
good, practice moderation in everything - but do so with moderation, don't
stare into operating microwave ovens, avoid badly burned food, avoid contact
with high temperature combustion products (motor oil etc), be aware that 12
VDC has killed by electric shock in extreme conditions, don't sniff PICs
(except in BGA or similar leadless packages),  consider not living in
congested / smoggy cities (but remember what happened at Lockerbie), fill in
the intentions book in every hut, emergency satellite locator beacons are
cheap to hire, excess alcohol and boating is a fatal mix, if you have a $10
head then buy a $10 helmet, death is nature's way of telling you to slow
down, eat broccoli, enjoy life, have fun, don't be paranoid, ...

:-)

This could be quite a fun list when complete.



       RM

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2004\08\06@043300 by Alan B. Pearce

face picon face
>> Not a good idea to Pee on one either!
>
>"Mythbusters" (a TV show on Discovery Channel Can)
>proved that you need not worry about this.
>Your pee stream always breaks up into droplets by
>time it could hit the fence (or third rail).

Try telling that to a past colleague of mine. he reckoned that although it
didn't actually get welded shut, it sure felt like that is what happened,
such was the pain :))))))))))

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@044335 by hael Rigby-Jones

picon face
>-----Original Message-----
>From: pic microcontroller discussion list
>[PICLISTEraseMEspamMITVMA.MIT.EDU] On Behalf Of Russell McMahon
>Sent: 06 August 2004 04:56
>To: RemoveMEPICLISTEraseMEspamspam_OUTMITVMA.MIT.EDU
>Subject: Re: [OT:] Microwave ovens was WIFI Waveguide antenna
>
> eat broccoli, enjoy life

Those two are mutualy exclusive for me! :o)

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@051940 by Russell McMahon

face
flavicon
face
> > eat broccoli, enjoy life

> Those two are mutually exclusive for me! :o)

I'm not a great Broccoli fan. But it is thought that it is one of the most
useful vegetables available due to various arcane components. I eat a little
in Chinese food occasionally and find with time that it becomes almost
bearable :-)

While on the topic - beware the processed vitamins route. Some of these have
their place no doubt BUT it appears that at least some which are
unquestionably effective when taken in their natural form, actually produce
adverse results when extracted and taken as a "supplement". One such is Beta
Carotene. So I'm afraid it's going to have to be carrots with your Broccoli
:-) !!!

Tomato cooked or raw has gotta be good for you fwiw.

Brighter the colour, better the result as a VERY rough rule of thumb.

Green tea can't hurt (I hope :-) ).

Ginkgo Biloba I'm not yet convinced about :-(





       R "by no means a health food freak" M

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@070538 by Howard Winter

face
flavicon
picon face
Robert,

Electric fences...

On Thu, 5 Aug 2004 13:53:05 -0600, Robert Rolf wrote:

> > Not a good idea to Pee on one either!
>
> "Mythbusters" (a TV show on Discovery Channel Can) proved that you need not worry about this.
> Your pee stream always breaks up into droplets by time it could hit the fence (or third rail).

Well I for one wouldn't trust my life (or... anything!) to this.  If the fence-wire is high/close enough I'm
sure the stream will still be intact.  Third rail *from a station platform* is probably safe, but if you're
standing beside the track, with the permanent way rising above you so the top of the conductor rail is quite a
bit above your feet, I certainly wouldn't try it!  Nor would I try it from a bridge onto an overhead wire
(third rail supplies here are 750V, overhead wires are at 25kV and kids occasionally get themselves killed by
dangling things over bridges on string).

> You basically need a garden hose to get enough volume to have a continuous stream.

Oh, you mean you hav...  <redfaced>  ;-)

I may try measuring unbroken-stream at some convenient point, and reporting back.

Cheers,

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@072653 by Howard Winter

face
flavicon
picon face
Rich,

On Thu, 5 Aug 2004 23:04:26 -0400, Rich wrote:

> While we do know that radiation intensity decreases as a square function with respect to distance

I've been thinking about this (always dangerous!) and it's based on isotropic radiation, isn't it?  The
emission spreads outwards in an expending sphere-shape, so the density reduces as the area of the sphere
increases, which is proportional to square-of-radius (QED).

BUT!  What if the radiator isn't isotrpoic, but has "gain" in a particular direction?  Surely the whole point
of a gain antenna is to increase the energy in the wanted direction at the expense of the other directions, so
there would be more energy at a given distance in the "gain" direction than inverse-square would indicate.
Maybe *much* more!

The extreme of this would be a collimated "beam" such as you'd get from a properly configured dish reflector.
Surely in this case the fall-off of intensity would be purely the "loss" aspect of the medium it's passing
through, which would be linear with distance, and may not be significant?  In this case the inverse-square law
would be misleading to the point of being dangerous - if the loss in air isn't significant, standing in or
passing through the "beam" you would encounter almost all of the energy being transmitted, with little regard
to distance.

Or have I just had too much coffee this morning?  :-)

Cheers,


Howard Winter
St.Albans, England

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@074349 by Howard Winter

face
flavicon
picon face
Russell,

On Fri, 6 Aug 2004 15:55:41 +1200, Russell McMahon wrote:

>...<
> Prudent avoidance.
> Practice prudent avoidance.

I've always tried to avoid Prudence - she's a nasty, vicious girl!  :-)

>...<

> the brighter the plant colour the better it is for you (usually)

Never heard this one - what about Foxglove (Digitalis) - that's pretty bright and not good except as a
medicine...

> practice moderation in everything - but do so with moderation

I think some people take moderation to extremes... :-)


> avoid badly burned food

Also avoid undercooked food!

> don't sniff PICs (except in BGA or similar leadless packages)

You're doing a Douglas Adams on us here, aren't you?  :-)

> consider not living in congested / smoggy cities (but remember what happened at Lockerbie)

Very sad that - living in a nice quiet village miles from anywhere, and someone drops a 747 on your house.
Rather supports the tenet: "Live for today", doesn't it?

> fill in the intentions book in every hut

This must be a Kiwi-thing - I think I know what it means but perhaps a short explanation, please?

> emergency satellite locator beacons are cheap to hire

Not in the UK they're not!  Emergency equipment always looks expensive for what you get, unfortunately, so
people still fly across the Channel in light aircraft with no liferaft, just lifejackets, whose main task in
this situation is to make it easier to find the body :-(

> excess alcohol and boating is a fatal mix

*Any* alcohol and flying is (if I can say this) even more so!  If you find you are incapable of sailing for
any reason you can just sit there and wait.  That option is not available if you're the pilot of an aircraft!

> This could be quite a fun list when complete.

Indeed, and you may be able to get it made into a poster, sell millions, and become a Very Rich Man.  Which is
probably bad for you...  ;-)

Cheers,


Howard Winter
St.Albans, England

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@074557 by Howard Winter

face
flavicon
picon face
Russell,

On Fri, 6 Aug 2004 21:18:50 +1200, Russell McMahon wrote:

> Ginkgo Biloba I'm not yet convinced about :-(

I'd always assumed this was some little herb-like plant, until I was on a bus-tour of Washington DC and they
pointed them out, planted along the streets (of Georgetown, I think) - they're stonking great trees!  :-)

Cheers,

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@080012 by John Ferrell

face picon face
A loong time ago I was measuring the output frequency of a 25 Watt
Navigation beacon transmitter (about 300khz) with a hand held counter at the
antenna when it arced over to the meter and then my hand . The arc entered
between my thumb & finger leaving a small cauterized hole It felt like a
needle had been inserted there and all the way up my arm. It took forever to
heal the entry wound. It smelled like burning flesh.

I have never been curious again about how bad a shock might be. I just don't
do it.

John Ferrell
http://DixieNC.US

----- Original Message -----
From: "Rich" <@spam@rgrazia1RemoveMEspamEraseMEROCHESTER.RR.COM>
To: <EraseMEPICLISTspam@spam@MITVMA.MIT.EDU>
Sent: Thursday, August 05, 2004 11:04 PM
Subject: Re: [OT:] Microwave ovens was WIFI Waveguide antenna

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@080636 by Russell McMahon

face
flavicon
face
> > While we do know that radiation intensity decreases as a square function
with respect to distance

> BUT!  What if the radiator isn't isotrpoic, but has "gain" in a particular
direction?  Surely the whole point
> of a gain antenna is to increase the energy in the wanted direction at the
expense of the other directions, so
> there would be more energy at a given distance in the "gain" direction
than inverse-square would indicate.
> Maybe *much* more!

If the radiator takes a spherical distribution and concentrates it into a
spherical segment with surface area an Nth of a sphere at a given radius
then you still get inverse square law but with a constant factor of N
stronger at a given distance. Classical gain antenna.

If you can manage to collimate the wavefront so that it is as parallel as
possible then you get something closer to what you are suggesting and
non-inverse-square dissipation.

One example of a strangely behaved waves are "Solitons" which have a decay
characteristic that causes them to reinforce themselves as they travel.
Early known examples occurred in English barge canals where occasional large
isolated waves were observed to travel at about fast horse back speed for
many miles with minimal loss of shape or amplitude. Doesn't break the laws
of physics - just explores them.

It seems intuitive (even if not correct :-) ) that waves / particles exhibit
Soliton behaviour.
Haven't Googled on solitons for some years but I'm sure there will be heaps
thereon.

Googles ...

182,000 hits.

Here they are attempting to recreate the original 1834 observation

       http://www.ma.hw.ac.uk/solitons/press.html

What say i stop there before another hour is blown :-)



       RM

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@081711 by Russell McMahon

face
flavicon
face
> consider not living in congested / smoggy cities (but remember what
happened at Lockerbie)

Very sad that - living in a nice quiet village miles from anywhere, and
someone drops a 747 on your house.
Rather supports the tenet: "Live for today", doesn't it?


I visited Lockerbie especially on our round-the-world trip. There are no
signs or notices. There is a large memorial at the town entrance but 99+% of
people who see it would not recognise it as such. That is intentional. They
go out of their way to make the cemetery inobvious to tourists. I can
understand and appreciate that. We were too awed to ask anyone for
directions. We found the cemetery in due course, out beyond the town. A most
awe inspiring and moving and saddening and uplifting experience. Maybe 10 or
so people there when I visited. I took my usual photos of the memorial
gardens etc BUT I was very very circumspect with the camera and felt more
like an intruder there than almost anywhere else I went.

> > fill in the intentions book in every hut
>
> This must be a Kiwi-thing - I think I know what it means but perhaps a
short explanation, please?

"Back country" huts have books where you record where you are intending to
go, how long you intend to be, where you plan to exit. Makes it easier to
find your body, as you say.

> > emergency satellite locator beacons are cheap to hire

> Not in the UK they're not!  Emergency equipment always looks expensive for
what you get, unfortunately, so
> people still fly across the Channel in light aircraft with no liferaft,
just lifejackets, whose main task in
> this situation is to make it easier to find the body :-(

Dirt cheap to hire in NZ. Just a few minths ago we had an Englishman doing a
substantial South island solo traverse. Said that locator beacons weighed
too much. had a fall. Was found dead about a month after reported overdue.
In his sleeping bag. had fallen and had sustained a broken something or
other. Obviously had been too damaged to proceed. Would quite possibly have
lived if he's had a locator beacon. Sad.



       RM

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@082747 by Jinx

face picon face
> > emergency satellite locator beacons are cheap to hire
>
> > Not in the UK they're not!

Most common phrase in friends e-mail during UK winter -

"another bunch of wallies lost on Snowdon"

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@083126 by Alan B. Pearce

face picon face
>One example of a strangely behaved waves are "Solitons"
>which have a decay characteristic that causes them to
>reinforce themselves as they travel. Early known examples
>occurred in English barge canals where occasional large
>isolated waves were observed to travel at about fast
>horse back speed for many miles with minimal loss of shape
>or amplitude. Doesn't break the laws of physics -
>just explores them.

Oh, you mean like the tidal surge up the Severn River. People can ride a
surfboard for several miles upriver on it.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@084204 by Jinx

face picon face
> Green tea can't hurt (I hope :-) ).

I faxed this to someone just the other day

http://smh.com.au/articles/2004/07/27/1090693968292.html?oneclick=true

Plenty of praise for green tea on the web

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@101851 by Russell McMahon

face
flavicon
face
> Most common phrase in friends e-mail during UK winter -
>
> "another bunch of wallies lost on Snowdon"

How could you get lost on Snowdon?
From what I could see you walked up to get up and down to get down.
Maybe I missed something :-)
(I was only looking from the high point on the road.)


       RM

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@104108 by David VanHorn

flavicon
face
>
>BUT!  What if the radiator isn't isotrpoic, but has "gain" in a particular direction?

Inverse square still holds, because the area painted will still be proportional to the square of the radius.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@125527 by Robert Rolf

picon face
Howard Winter wrote:
{Quote hidden}

The show was actually quite hilarious as they tried many different
ways to get their life sized dummy to pee correctly. Used a balloon
filled with saline emptying through a small hose. Windshield washer
pump and reservoir, etc. In each case the stream broke into
drops about 18" out so they finally had the dummy kneeling over the
simulated 3rd rail draining straight down to get the conductive
circuit.

dsc.discovery.com/fansites/mythbusters/mythbusters.html
http://dsc.discovery.com/fansites/mythbusters/episode/episode.html

Episode 3: Barrel of Bricks, Pissing on the Third Rail, Eel Skin Wallet

Is it really that dangerous to answer the call of nature on the
electrified third rail of a train track? Can an eel skin wallet erase
all the magnetic information on your credit cards if the skin came from
an electric eel? How about the story of the unluckiest construction
worker on earth? A pulley system breaks down while he is lifting a
barrel filled with 500 pounds of bricks. Will the barrel come straight
down on the guy doing the pulling, or will he walk away without a
scratch? Jamie and Adam take a crack at these classic legends.

Now if you are peeing on the fence from 6" away, at waist height,
you may well get a memorable experience.

Now if I could only electrify the big rock at our property line
that the local dogs have to 'mark', without getting caught <G>.

Robert

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@125943 by David VanHorn

flavicon
face
> Can an eel skin wallet erase all the magnetic information on your credit cards if the skin came from an electric eel?

Not exactly.

Eel skin wallets did cause a major upheval in the credit card industry.
Of course the problem was not the Eel skin itself, but the MAGNETIC closures they used.

Just call me an expert witness on this one.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@185703 by Russell McMahon

face
flavicon
face
> >BUT!  What if the radiator isn't isotrpoic, but has "gain" in a
particular direction?
>
> Inverse square still holds, because the area painted will still be
proportional to the square of the radius.

This assumes (As I noted) that the radiation is effectively just confined to
a spherical subset and is effectively a point source at point of origin. If
the radiator is a non point source that collimates the wave IMO you get non
inverse-square results. Examples might be phased array type systems.

B, IMBW :-)  (as Carl Sagan was fond of saying).



           Russell McMahon

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@190530 by David VanHorn

flavicon
face
At 05:56 PM 8/6/2004, Russell McMahon wrote:

>> >BUT!  What if the radiator isn't isotrpoic, but has "gain" in a
>particular direction?
>>
>> Inverse square still holds, because the area painted will still be
>proportional to the square of the radius.
>
>This assumes (As I noted) that the radiation is effectively just confined to
>a spherical subset and is effectively a point source at point of origin. If
>the radiator is a non point source that collimates the wave IMO you get non
>inverse-square results. Examples might be phased array type systems.

Not too likely in the case of the dropped microwave oven.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@203328 by Russell McMahon

face
flavicon
face
> Not too likely in the case of the dropped microwave oven.

Agree.
The person who suggested this was making a more general case AFAIR.

       RM

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\06@205233 by Rich

picon face
True: The inverse square relation still holds.

----- Original Message -----
From: "David VanHorn" <@spam@dvanhornspam_OUTspam.....CEDAR.NET>
To: <spamBeGonePICLISTEraseMEspamMITVMA.MIT.EDU>
Sent: Friday, August 06, 2004 7:06 PM
Subject: Re: [OT:] Microwave ovens was WIFI Waveguide antenna


> At 05:56 PM 8/6/2004, Russell McMahon wrote:
>
> >> >BUT!  What if the radiator isn't isotrpoic, but has "gain" in a
> >particular direction?
> >>
> >> Inverse square still holds, because the area painted will still be
> >proportional to the square of the radius.
> >
> >This assumes (As I noted) that the radiation is effectively just confined
to
> >a spherical subset and is effectively a point source at point of origin.
If
> >the radiator is a non point source that collimates the wave IMO you get
non
> >inverse-square results. Examples might be phased array type systems.
>
> Not too likely in the case of the dropped microwave oven.
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.
>

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

2004\08\07@111841 by Peter L. Peres

picon face
>Also, a special parabolic antenna design can focus the uWave at a
>specific (x,y,z) point.  The energy can also be made to concentrate at
>that point. These techniques are also used in optics.  You can get
>seriously hurt by attempting experiments you are not ready for.

And you do not need a microwave oven for that, the sun is plenty enough.

Peter

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listservspamBeGonespammitvma.mit.edu with SET PICList DIGEST in the body

2004\08\11@075149 by Jinx

face picon face
> be forewarned that in older ovens without carousels, water in
> a container sitting very still can become superheated in a
> microwave oven.  Upon disruption by some object (thermometer
> in this case) the superheated (above boiling point but not
> boiling) water can and will explode out of the container as it all
> instantaneously boils over, flashing to steam and covering the
> unsuspecting "scientist" with boiling water

Located my video of this today (it's tiny - 65kB)

http://home.clear.net.nz/pages/joecolquitt/hotstuff.html

(I noticed the date I made this was 13/4/01 - getting old too quick)

The man with the beaker said it felt "not uncomfortably hot". Then
he dropped the coffee in - and whoosh

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.

More... (looser matching)
- Last day of these posts
- In 2004 , 2005 only
- Today
- New search...