FW: incand lamps debate [wasRe: [LINK] Here's one that will snaga few]

[Adam Todd]

At 06:04 PM 22/02/2007, Daniel Rose wrote:
>SNIP.
>
>It's alleged that you can 'harvest' the energy from a radio
>transmission, perhaps those of you with greater experience can confirm
>or debunk this.

Yes you can.

The most basic and comreghensive example of all time, is the CRYSTAL RADIO!

Yes, with just 6 components, you can build a radio receiver that will allow 
you to tune the worlds airwaves and hear the signals.  Most are in the low 
AM broadcast band, but with a little knowledge or random changing of 
components, you can tune to nearly any band and listen to the AM singals.

That is powered by the INBOUND signal only.  No batteries needed.  I 
actually carry a mini circuit diagram and the components in my wallet.  You 
never know when you might need to build one in an emergency :)

Any example for the Covert Operative is a 2 MHz Transmitter sending a 
carrier wave with say 20 watts of power via a somewhat directional antenna 
(might be a BIG ONE! but not necessarily so) in bursts of say 10 minutes, 
every hour for 24 hours can supply enough RF energy to power a 3.3 volt 
listening device with a 400 Mhz transmission and charge an onboard battery 
to enable that device to run for 24 hours straight.

Using other frequencies to transmits similarly will yield similar results.

What you might do with a remote device is "talk to it" with high power, so 
that your inbound transmissions are updating software and requesting 
downloads, and at the same time charging the battery and supplying the 
power for the download!

RF Detectors commercially available now, once the domain of the TSCM covert 
agent, can detect transmissions from miles away.  Connect in a Frequency 
Counter, isolate a frequency and tune in and see if there is anything of 
interest.

This isn't a self powering example, but it does show how the smallest of RF 
signals can generate power to drive a circuit.  Again the Crystal Radio.

I only skimmed the web page you offered Danny and it's certainly interesting!

An alternative with greater depth to the concept of increasing the power 
out put of a powerless device.  RFID basically works this way.  Unlike 
remote powered listening devices which are obviously far more complex in 
purpose, design and structure.

I love the idea of a 2K resonating wave supplying world power :)

But then we have the Sun and it's power output is greater than anything we 
can store and use in a millisecond.  We're just too busy burning fossil 
fuels to actually spend time capturing the unlimited and timeless energy 
from the one source that powered this planet for billions of years before 
humans made combustion engines.

>This of course creates a large radio shadow; those behind will get no
>signal, so this is probably a bad idea; especially if it yields the kind
>of energy that the article mentions.
>
>This sounds like one for Adam Todd to explain.

ROFL!  Thanks Danny :)

Hope I did simple enough.