Can I light an LED with just an antenna?

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Patrick Leonard

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Subject pretty much says it all........is it possible to light an LED
(continuously, or pulsed) from an antenna ONLY (only power source, that is)?
Does anyone know of any schematics for building such a circuit?
 
Patrick Leonard <transactoid@rogers.com> wrote:
You need to look up Nikola Tesla, that was his gig around the turn of the
(20th) century.

DLC

: Subject pretty much says it all........is it possible to light an LED
: (continuously, or pulsed) from an antenna ONLY (only power source, that is)?
: Does anyone know of any schematics for building such a circuit?





--
============================================================================
* Dennis Clark dlc@frii.com www.techtoystoday.com *
* "Building Robot Drive Trains" published by McGraw-Hill 2002 *
============================================================================
 
I'm familiar with the work of Tesla; no this question was not an attempt at
any kind of free energy extraction.

I'm just curious if radio stations (and other sources) produce enough RF
that an LED, with a suitable antenna, could be lit.

"Dennis Clark" <dlc@io.frii.com> wrote in message
news:3f29cace$0$194$75868355@news.frii.net...
Patrick Leonard <transactoid@rogers.com> wrote:
You need to look up Nikola Tesla, that was his gig around the turn of the
(20th) century.

DLC

: Subject pretty much says it all........is it possible to light an LED
: (continuously, or pulsed) from an antenna ONLY (only power source, that
is)?
: Does anyone know of any schematics for building such a circuit?





--

============================================================================
* Dennis Clark dlc@frii.com www.techtoystoday.com
*
* "Building Robot Drive Trains" published by McGraw-Hill 2002
*

============================================================================
 
Clearly, you do not understand Tesla's work at all! He was not some
sort of
"free energy" idiot like the many drooling, credulous followers of his
work. He
transmitted power and extracted it at a distance. The reference was meant
to
point out that radio waves are sometimes used to do this.
I DO know Tesla's work quite well, and I realise my reply was misleading. I
didn't mean to imply Tesla was a free energy kook, rather, I wanted to make
it clear that *I* was not a free energy kook misinterpereting his work. I
apologise if this was unclear.


Not unless you are right by the antenna. A few turns of wire can
sometimes
do the trick, and the LED acts as the rectifier. Imagine that you have a
full
wave antenna. At either end of the antenna, when immersed in an RF field,
there
will appear an AC signal that oscillates at the carrier frequency. Now,
if the
LED were wired to each tip of the antenna, it would "see" the voltage
potential
that exists across the tips of the antenna.
Now, wind it up into a coil so it is smaller. It will not be as
efficient
but it will still develop a voltage potential that is applied to the
terminals
of the LED. Just to protect it in strong RF fields, place another LED in
anti-parallel (or a small diode) to short out the reverse current. And if
you
make a tuned circuit with a small capacitor, it can actually "store" a
small
amount of power and then act as a resonant element- giving you a bit more
light.
Think of two identical tuning forks placed a short distance apart. If
you
tap one and then stop its oscillations with your hand, you will hear a
faint
sympathetic oscillation from the second. You have induced it to ring.
Tuned circuits can do this as well; resonance is the key to
efficiency.
Make your coil your tuned circuit. That is what many RFID tags do.

Cheers!
Well, this is what I have been experimenting with using a plasma ball (see
my other post regarding antennas). But trying to hook up the LED across the
antenna doesn't seem to do the trick. Rather, it only works when I wire the
antenna, LED, and a ground in series (and it doesn't even have to be a good
ground)
 
I asked pretty much the same question a couple of years
ago, and was pointed to web sites dedicated to "crystal
radio" which basically powers the high impedance headphone
rather than the LED (+demodulates AM, but that you don't
care about). I was also pointed to the web site of someone
living under high voltage power lines who could light a
light bulb just by induction (with the proper loop antenna
of course).

Unless you have dedicated circuitry for transmitting energy
via RF (two coil/loop antenna setup), the energy output of
an antenna will most probably not be enough for anything
useful (I even tried to power one of the low power microcontrollers
from an antenna+rectifier bridge). An example of such setup
is the SAW based RF tags.

Jean-Michel
 
In article
<_zjWa.34551$hOa.11712@news02.bloor.is.net.cable.rogers.com>,
transactoid@rogers.com mentioned...
Subject pretty much says it all........is it possible to light an LED
(continuously, or pulsed) from an antenna ONLY (only power source, that is)?
Does anyone know of any schematics for building such a circuit?
Yeah, you just bend the LED leads in the shape of a dipole antenna.

Somewhere I read about using just such a device to find out if your
microwave oven is leaking microwaves around the door. You just dim
the room lights, and put a cup of water in the microwave and turn it
on high. Then hold the LED with its legs bent like an antenna next to
the door edges, and see if it lights up.

If it does, then you got a problem!


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
In article
<YykWa.13438$4UE.1422@news01.bloor.is.net.cable.rogers.com>,
transactoid@rogers.com mentioned...
I'm familiar with the work of Tesla; no this question was not an attempt at
any kind of free energy extraction.

I'm just curious if radio stations (and other sources) produce enough RF
that an LED, with a suitable antenna, could be lit.
Your average local radio station has millivolts of signal strength,
but that can be stepped up to a higher voltage, with a coil. If
you're close to a high power radio transmitter, then it's possible to
light up things like neon lights, etc. One guy claimed that the
electric lights in his chicken coops lit up from the local radio
station transmitter, so he could get the chickens to lay more eggs.
Don't remember why, tho.

I've used a red LED connected to a coil of a few turns of 24 gauge
wire to sense RF when I'm playing.. erm, experimenting (yeah, that's
the word) with transmitters. But a 1.5V, 25 mA submini bulb from
Radio Scrap works very well, too.

You can get on Gollum's website of crystal radios and see the
schematics of some of the self-powered xtal radios he's built.
Basically they rectify the RF from the antenna and use it to power 1
or 2 transistors to amplify the AF signal. This could be enough to
light up a LED. I've run as little as a few tens of microamps or less
thru a blue or white LED and it's clearly visible, which makes you
think about how amazingly sensitive the eye really is. You go outside
and look at the stars, and you see some tiny speck in the sky
twinkling. How much is the power of that starlight hitting your
retina? Nanowatts? Picowatts? Femtowatts? Whatever..
See here for the next lower prefix for the above.
http://physics.nist.gov/cuu/Units/prefixes.html


"Dennis Clark" <dlc@io.frii.com> wrote in message
news:3f29cace$0$194$75868355@news.frii.net...
Patrick Leonard <transactoid@rogers.com> wrote:
You need to look up Nikola Tesla, that was his gig around the turn of the
(20th) century.

DLC

: Subject pretty much says it all........is it possible to light an LED
: (continuously, or pulsed) from an antenna ONLY (only power source, that
is)?
: Does anyone know of any schematics for building such a circuit?
--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
In <YykWa.13438$4UE.1422@news01.bloor.is.net.cable.rogers.com>, Patrick
Leonard wrote:
I'm familiar with the work of Tesla; no this question was not an attempt
at any kind of free energy extraction.

I'm just curious if radio stations (and other sources) produce enough RF
that an LED, with a suitable antenna, could be lit.
Done that half a kilometer from a major AM transmitter site. String out
(as in outdoors) a long wire (several meters but less than 1/4
wavelength), and put an inductor from one end to ground that makes this
resonate. Halfwave rectify (with respect to ground) where the antenna
meets the inductor. Maybe you get adequate voltage at around a milliamp
to optimistically possibly a few milliamps, enough for better modern blue,
white, or InGaN green LEDs to be used as a dimmer sort of nightlight. You
can illuminate a room well enough from this to navigate through if
dark-adapted.

CAUTION:
1: the current through the diode (and maybe through the LED) may
have enough harmonic content to possibly result in rebroadcasting the
nearby AM station at harmonic frequencies to an extent that you may not be
allowed to do.
2: Particularly large/nearby/efficient powersucking antennas may
measurably decrease reception somewhere else or may measurably affect the
impedance of the transmission antenna or may measurably detune it, which
may possibly cause yourself trouble.
3: What will you do about lightning? A near-miss may send pieces of
your LED all over the place. A direct hit can do worse.

- Don Klipstein (don@misty.com)
 
Watson A.Name - 'Watt Sun' wrote:
In article
_zjWa.34551$hOa.11712@news02.bloor.is.net.cable.rogers.com>,
transactoid@rogers.com mentioned...
Subject pretty much says it all........is it possible to light an LED
(continuously, or pulsed) from an antenna ONLY (only power source,
that is)? Does anyone know of any schematics for building such a
circuit?

Yeah, you just bend the LED leads in the shape of a dipole antenna.

Somewhere I read about using just such a device to find out if your
microwave oven is leaking microwaves around the door. You just dim
the room lights, and put a cup of water in the microwave and turn it
on high. Then hold the LED with its legs bent like an antenna next to
the door edges, and see if it lights up.

If it does, then you got a problem!
Oh Dear! I've one of those cell-phone cradles with a black-blob flasher
circuit that goes off when the phone rings - it flashes if stood on top of
the operating microwave (on the steel case). Thinking even thin steel would
stop any harmful radiation, I've put this down to some less nasty form from
the transformer...
 
In article <bggmv3$t2e$1@newsg4.svr.pol.co.uk>, cpm@mexbroREMOVE.co.uk
mentioned...
Watson A.Name - 'Watt Sun' wrote:
In article
_zjWa.34551$hOa.11712@news02.bloor.is.net.cable.rogers.com>,
transactoid@rogers.com mentioned...
Subject pretty much says it all........is it possible to light an LED
(continuously, or pulsed) from an antenna ONLY (only power source,
that is)? Does anyone know of any schematics for building such a
circuit?

Yeah, you just bend the LED leads in the shape of a dipole antenna.

Somewhere I read about using just such a device to find out if your
microwave oven is leaking microwaves around the door. You just dim
the room lights, and put a cup of water in the microwave and turn it
on high. Then hold the LED with its legs bent like an antenna next to
the door edges, and see if it lights up.

If it does, then you got a problem!

Oh Dear! I've one of those cell-phone cradles with a black-blob flasher
circuit that goes off when the phone rings - it flashes if stood on top of
the operating microwave (on the steel case). Thinking even thin steel would
stop any harmful radiation, I've put this down to some less nasty form from
the transformer...
Tsk-tsk..

I scrounged a magnetron from a defunct microwave oven at work, and put
it in my desk. I decided that it needed more exposure, so I took it
along on one of my sojourns to another campus. I showed it to some
people and they said, what's that? I said it's a magnetron. They
said, so, what's a magnetron? Well, I said, this is what makes the
microwaves in your microwave oven. Oh, they say, and look at it a bit
more closely. But most people haven't a clue as to what is inside
their microwave oven, other than the plate that spins around.


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 

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