very close range wireless charger

[dpopiz]

These days we have so many little electronic devices that all require charging. The chargers just create a big ugly mess of wires though, and I'm sure a lot of people would rather not deal that big mess..

Wouldn't it be possible to make a wireless charger by the following:

A desktop, or floortop little "charging beacon" could plug into the wall. I would then emit high power and EXTREMELY HIGH FREQUENCY microwaves. the higher the frequency, the shorter the propgation range right? so if it were high enough, it could maybe work up to 3cm before the radiation is too low to be detected (so as not to cause possible health risks) your electronic device requiring recharge would contain an antenna and circuitry to turn the high frequency radiation into a steady DC current.

So whenever you want to recharge something, you just drop it next to the "charging beacon".

 

[bobsmith1492]

Just use a torroidal transformer w/ a hollow core and drop your item to be charged (with another coil in it) into the charger. They have them already.

 

[AFB]

Go to Target and look at the Sonic Care tooth brushes.

 

[dpopiz]

I know about those; I have a sonicare, but the problem is that you need one for each device then. This way you could just have one recharger thing and drop all your devices next to it

 

[f95toli]

Originally posted by: dpopiz
I would then emit high power and EXTREMELY HIGH FREQUENCY microwaves. the higher the frequency, the shorter the propgation range right?".

No, that is only true for propagation in metals (skin effect), in air there is no such relation. Basically the maximum range depends on the amount of absorbion which in the sub-terahertz region is mainly due to absorbtion in certain molecules (vibrational spectra at 300-600 GHz if i remember correctly).
You can easily transmitt even very high frequencies over rather large distances. One reason why high frequencies are not used very often is that it is very hard to generate microwaves in the 100 GHz-1.5 THz range (above that you can simply use infrared lasers). However, using Backward Wave Oscillators (BWO) you can generate microwaves in this range (but only a few mW of power) which is interesting for spectroscopy (which is what I have used BWOs for) but useless for power transfer,

 

[Safeway]

I like the prototype power table that I saw. You buy a "computer desk" with a special covering. Then there are electronics that are designed for this surface. For instance, a PDA with contact points on the back so it can charge lying down. Or a LCD monitor with contacts on the bottom - no additional power cord. Other ideas were speakers, wireless mouse/keyboard, etc etc. The table doesn't shock people!

I can't remember where I saw it, but this thing was running/charging a prototype PDA.

 

[jagec]

"wireless" charging is so incredibly inefficient, I'd MUCH rather use wires.

I remember someone rigged up a cordless optical mouse that drew all its power from wires coiled under the mouse pad..interesting, but impractical.

 

[bsobel]

Originally posted by: Safeway
I like the prototype power table that I saw. You buy a "computer desk" with a special covering. Then there are electronics that are designed for this surface. For instance, a PDA with contact points on the back so it can charge lying down. Or a LCD monitor with contacts on the bottom - no additional power cord. Other ideas were speakers, wireless mouse/keyboard, etc etc. The table doesn't shock people!

I can't remember where I saw it, but this thing was running/charging a prototype PDA.

I saw two companies last year promsing this soon (I can't wait!)
Bill

 

[element]

Originally posted by: bsobel

Originally posted by: Safeway
I like the prototype power table that I saw. You buy a "computer desk" with a special covering. Then there are electronics that are designed for this surface. For instance, a PDA with contact points on the back so it can charge lying down. Or a LCD monitor with contacts on the bottom - no additional power cord. Other ideas were speakers, wireless mouse/keyboard, etc etc. The table doesn't shock people!

I can't remember where I saw it, but this thing was running/charging a prototype PDA.

I saw two companies last year promsing this soon (I can't wait!)
Bill

Sounds like it would make it difficult to move these items around. You're pretty much stuck putting the LCD screen where the contacts are on the table rather than wherever you like, too restricting if you ask me.

And OP leave the hair brained schemes in electrical engineering to the EEs pls. No offense but you sound clueless about how it all works.

 

[Safeway]

Originally posted by: element

Originally posted by: bsobel

Originally posted by: Safeway
I like the prototype power table that I saw. You buy a "computer desk" with a special covering. Then there are electronics that are designed for this surface. For instance, a PDA with contact points on the back so it can charge lying down. Or a LCD monitor with contacts on the bottom - no additional power cord. Other ideas were speakers, wireless mouse/keyboard, etc etc. The table doesn't shock people!

I can't remember where I saw it, but this thing was running/charging a prototype PDA.

I saw two companies last year promsing this soon (I can't wait!)
Bill

Sounds like it would make it difficult to move these items around. You're pretty much stuck putting the LCD screen where the contacts are on the table rather than wherever you like, too restricting if you ask me.

And OP leave the hair brained schemes in electrical engineering to the EEs pls. No offense but you sound clueless about how it all works.

Not at all. The entire table is electrified. You can slide them, pick them up and move, etc. I can't remember exactly, but the size of the contacts on the object would -always- be on contacts. If the entire table is covered, there's no problem. If you had a shelf, you could buy a mat to lay down.