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Topic: Ambient radio wave energy (Read 8965 times) previous topic - next topic

arduinopi

I am trying to do a demonstration in which energy from ambient radio waves (it doesn't matter which frequency) is used to charge up capacitors and blink a red 3 volt 1 mA led every 10 seconds or so. Is this feasible? If so how can I go about building it.

PaulS

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Is this feasible?

It doesn't seem likely.

What does this have to do with the Arduino?

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If so how can I go about building it.

First, you'll need a couple of gallons of snake oil.
Then, you'll need a functioning perpetual motion machine.
After that, the rest is easy.
The art of getting good answers lies in asking good questions.

fungus


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Is this feasible?

It doesn't seem likely.


Why not? People used to listen to radio without amplifiers.

https://en.wikipedia.org/wiki/Crystal_radio

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

Erdin

The capacitors are a problem: they leak.
Blinking a led requires more energy than audio in a piezo (crystal) earphone.
The led has to blink long enough to be visible, that would be about 100ms. The 1mA during 100ms needs a lot of energy.

Powering an LCD clock would be easier. Even a larger LCD display requires almost no current.

There is a problem with radio waves: If you use only a coil, you get a lot of everything, but the result is almost nothing.
However, if you tune in to a strong radio station, you can get energy out of that.
Try to make an antenna, like a circular coil of 1 meter (or 1 yard) diameter. About 50 to 500 windings. Don't use very thin copper wire, that reduces the current. Add a variable capacitor and a radio diode. The diode to a capacitor and see if you can charge the capacitor when tuning to find a radio station.

pito

It is feasible, there are topics on the web where people try to develop wirelesses hubs powered from such energy. The most energy you get today would be from VHF/UHF spectra, especially from your local digital television, FM radio, and mobile phone providers (90-1900MHz). You need a dipole tuned a frequency with most power density, with a diode as an detector - charging a ceramic capacitor..

AmbiLobe

Here is an example solution:
http://www.ebay.com/itm/370877977659

It picks up radio energy and lights LEDs.

Erdin

My idea (LW and MW waves) is totally different from catching energy from GHz signals.
Flashing a led with a mobile phone is only for a very short distance.
It is hard to say which signal is strong enough.
A good quality spectrum analyzer will show what is in the air.

Do we agree ? That getting energy from all frequencies at the same time is very hard ? And by tuning to a frequency you have to know about a strong signal.

jremington

Yes, there is enough power in MW, etc. to power sensitive headphones, but then our ears are unbelievable sensitive devices!

There is a commercial device called "Airnergy" that claims to harvest energy from WiFi hotspots to charge batteries.
Dave Jones has a hilarious review of this at http://www.eevblog.com/2010/01/17/eevblog-55-rca-airnergy-wifi-hotspot-energy-harvesting-marketing-bs/

On the other hand, if you suspend a plate of metal under a high tension power line, you can easily harvest enough energy to light up a fluorescent lamp. See Richard Box's incredible "field of light bulbs" art project at http://www.stopgeek.com/richard-boxs-light-field.html
No PM's please.

Grumpy_Mike

Back in the 60s I made a radio that was powered by the local long wave transmitter.

Also there was a man who lived close to a very long wave radio mast. He filled the loft with a criss cross of wires and used the energy to charge 12V batteries. Unfortunately the  mast was used to communicate with nuclear submarines, and it put a dent in the radiation pattern, making it impossible to communicate with them. Even more unfortunately this null was in the direction of Moscow and it was thought to be some sort of Soviet jamming device. When he was tracked down he got three years in prison for illegal use of electricity. 

Docedison

There is another.. Regulatory problem.. the EU, GB (I believe and the US to name a few have laws about the allowable RF power that a human being can be safely exposed to and it's in the crystal Radio class...  A high efficiency red led will show some light @ 1V8 and 500 or less uA or ~9 mW. There is also the thought that the human body is considerably larger and can absorb a lot more power.  I know of three radio tech's that are now deceased.. all about the same age and all of brain tumors.
BTW Crystal headphones didn't become popular until the mid to late 50's. They were the really cheap replacement for a much more expensive high resistance type of magnetic earphone that was very sensitive. Brush, I think were the best. Second best was the receiver in a telephone of that era.

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

fungus


There is a problem with radio waves: If you use only a coil, you get a lot of everything, but the result is almost nothing.


I never said it was easy... :-)

You'd certainly have to tune to the frequency of the most powerful transmitter in your area or the energy will cancel out.
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

mrburnette

As with any receiver, the trick is with antenna design:
http://www.gizmag.com/scavenging-ambient-electromagnetic-energy/19163/

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Tentzeris says exploiting a range of electromagnetic bands increases the dependability of energy scavenging devices as if one frequency range fades due to variations in usage, other frequencies can be used to pick up the slack.

The team is also looking at combining the energy scavenging technology with supercapacitors and cycled operation so that the energy builds up in a battery-like superconductor and is utilized once the required level is reached. The team expects this approach would be able to power devices requiring over 50 milliwatts.

UserNotLoggedIn

I'm going to suggest a long, random wire antenna to scavenge the bulk of AM broadcast stations in your area.
This wire will couple a fair amount of low freq energy into your diode rectifier/cap storage circuit.
Expect to capture power line radiation, low band Ham radio, AM broadcast, lightning induced energies etc.
Ideally you would use an antenna length "tuned" for the band where you find the most energy.
By random length wire, I refer to something at least 100ft long or more (more being better).
You can try bending & moving the antenna around to get a better signal.
I would not expect to capture any microwave energies since they are usually point to point & overhead.
You might catch some FM & TV station energies if they are close enough.
I would use a sensitive diode like a 1N60 or the like. Perhaps there's a schottky diode offering a high sensitivity.
I doubt you'll power this for long unless your energy sources are strong.
You may need to investigate switching type, low dropout voltage regulators instead of what may be on brd.
Most linear regulators just waste too much energy doing their jobs & you don't have much to waste.
bc

cjdelphi

If you're willing to spend the money, you can now buy energy harvester ics which do very little except collect energy from it's surroundings until it's charged a cap enough to power up a circuit broadcast the data and goback to sleep.

Erdin

Do you know an energy harvesting ic that collects energy from radio waves ?
I can only find ics that use motion, or peltier, or solar, or nearby inductance, and so on.

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