Friends Kingdom: Re: [iPad] Case charges phones using radio waves

There is a very big difference between a tracker and an iPad ? I have a toothbrush that charges without any electrical connection, but you have to set it on its base. Basically it is just a transformer with one winding int the base and one in the toothbrush handle. They have to be close coupled for it to work.

You can't get free energy from radio waves to power your cell phone unless you want to stick it in a very strong field like a microwave

Sent from my iPad

Jim Coon

On Jun 5, 2015, at 8:07 PM, Jim Saklad jimdoc@icloud.com [iPad] <iPad@yahoogroups.com> wrote:

>>> Beamed power has been shown to be possible for many decades. So far, it has not been shown to be particularly *practical*.
>>
>> I'm an electrical engineer and ham radio operator and I say this is junk science
>
> You are in good company.
> Edison had major disagreements with Nicola Tesla as well — for example, as to the usefulness of alternating-current.

<http://www.engadget.com/2015/06/05/wifi-powers-fitness-tracker/>

Scientists beam power to a fitness tracker via WiFi

Wireless electricity transmission sounds... dangerous, but the ability to do it could transform the internet of things. Researchers from the University of Washington have charged a JawBone UP24 fitness tracker with nothing but ordinary WiFi. They noticed that regular, ambient WiFi was strong enough to power a variety of tiny devices, but only in micro-bursts. So, they inserted "noise" into the signals to keep the power levels steady without disrupting data transmission. Using the technique, which they dubbed "PoWi-Fi" (we vote for just "Pow-Fi") they ran a low-power surveillance camera and temperature sensor from up to 6 meters (20 feet) away from the WiFi antenna.

Not content with that, the team ratcheted up the experiments. They found that by adding a rechargeable battery, the same camera could be powered from up to 7 meters (23 feet) away, even through a brick wall. They then tested the setup in six homes and found that the modified routers had no impact on data rates in the real world. Finally, they charged a Jawbone UP24 sports tracker via PoWi-Fi to 41 percent in just two-and-a-half hours.

It's still early days, and more tests need to be done. But if you've ever changed the battery in a wireless remote camera or climate sensor, you might be able to smell the potential. If you could power those devices from a regular WiFi router instead, it could transform the internet of things into much cheaper and more usable idea.

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Jim Saklad mailto:jimdoc@icloud.com