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WTF ! MIT to eliminate power cords ?

J

John Larkin

Jan 1, 1970
0
Sounds like there are some shysters that want lots of money and do
not care about a "little" fraud.
An electromagnetic field, BY DEFINITION cannot be "non-radiative" !!
Furthermore, by definition, something that is "non-radiative" goes
nowhere (unless we are talking about a gas which *diffuses* or a liquid
that *flows*).

Then again, the subject is about money that does not radiate from
suckers to liars.


I think they mean that it's a low-frequency H-field only effect, so
very little of the transmit coil excitation winds up being radiated.
It's just coupled resonators, not a surprise for the last 400 years or
so.

As a way to waste energy and enhance global warming, this scheme is
hyper-politically-incorrect.

John
 
R

Richard Henry

Jan 1, 1970
0
I think they mean that it's a low-frequency H-field only effect, so
very little of the transmit coil excitation winds up being radiated.
It's just coupled resonators, not a surprise for the last 400 years or
so.

As a way to waste energy and enhance global warming, this scheme is
hyper-politically-incorrect.

John- Hide quoted text -

- Show quoted text -

The pictures in the news show devices without power cords. They also
show them without the (presumably massive) receiving coils.

But this leads to another idea. Couldn't cell phones be charged by an
appropriate coil placed under a high tension line?
 
K

krw

Jan 1, 1970
0
Now if it was a TTL Analog Multiplexer it would have been
interesting.

Not a problem. Use a TTL OC output to tie inputs of an opamp summer
to ground:

___ ___ ___
A1 o--|___|-------.-|___|------o-----|___|- -------|
| | |
___ | ___ | |\| |
A2 o--|___|- -o---)-|___|------o-----|-\ |
| | | >- --------|-----
| | ---|+/
| | | |/|
__ | | |
Inh1 -| \ | | o
| )o--} GND
-|__/ |
|
__ |
Inh2 -| \ |
| )o------
-|__/
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

It's not a great analog switch, but it works.
 
K

krw

Jan 1, 1970
0
To-Email- said:
I think there several unfortunate changes...

Anyone know a kid who "tinkers" with electronics, builds his own
stuff, _even_ from kits?

No. It seems to be a lost hobby. Even RadioShaft gave up on it.
Even MIT now calls the department "Electrical Engineering and Computer
Science".

UIUC changed theirs to the "Department of Electrical and Computer
Engineering" when I was there in the early '70s. At least it was
still hardware oriented then. My nephew graduated from there five or
six years ago with a specialty in Linux (well, almost).
I'm of the old school... I wouldn't allow calculators until college,
and no simulators until senior year ;-)

I hate to think I'm as old as you, but I'm with ya'! I see
calculators in elementary school and cringe.
It's pretty clear from the postings on just this newsgroup that the
youth of this day (and even most adults) don't have a clue about
electronic fundamentals... if they can't cut and paste it from some
App Note they don't have even a single idea as to where to begin :-(

It's worse. Many don't know what an AppNote is, much less what to do
with one.
 
M

Michael A. Terrell

Jan 1, 1970
0
krw said:
Not a problem. Use a TTL OC output to tie inputs of an opamp summer
to ground:

___ ___ ___
A1 o--|___|-------.-|___|------o-----|___|- -------|
| | |
___ | ___ | |\| |
A2 o--|___|- -o---)-|___|------o-----|-\ |
| | | >- --------|-----
| | ---|+/
| | | |/|
__ | | |
Inh1 -| \ | | o
| )o--} GND
-|__/ |
|
__ |
Inh2 -| \ |
| )o------
-|__/
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

It's not a great analog switch, but it works.



You are ignoring that a typical analog switch is bi-directional.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
M

Michael A. Terrell

Jan 1, 1970
0
krw said:
Ok, drop the opamp.


Now you are ignoring the 'on resistance'.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
M

Michael A. Terrell

Jan 1, 1970
0
krw said:
I said it wasn't great. I just said it could be done. ;-)


So, the real question is, would you use it in a real design? ;-)


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
H

Helmut Sennewald

Jan 1, 1970
0
I sure hope they're well embarrassed for claiming to have invented
anything in that area. How much funding do you suppose it will get
them?

BTW, I believe it stated in that very article (which I don't at all
blame you for not reading in its entirety) that efficiency was on the
order of ~42%, and that they'd have to spend two to five years working
on it in order to double it to a useable level.

Maybe for their next trick they'll reinvent AC.


Hello,

I tried to calculate some numbers and here are my results.

As supposed by the "inventors", the coils are used in resonant mode
at medium wave frequency (1MHz or higher). Only the B-field
is used to transfer power.

A reasonable effeciency will require a high Q of let's say 1000. This
also means you have to tune the resonance frequeny of your receiver
coils with high precision, e.g. 0.2e-3.

The sender coil has an unductance of some ten mirco Henries.
By the way the coupling factor is in the range of 1e-4 to 1e-3 in the
proposed distance with a receiver coil of the same dimensions as the sender
coil.

The voltage along the coil maybe Kilovolt(s) due to the resonance.
This means strong E-fields close to the coil too.

It's true that the unwanted transferred power into non-tuned loops can
be neglected regarding power in the proposed distance. This may not
be true very close to the coil.

The B-field is below the earth magnetic field but it's alternating with MHz.
So it doesn't make sense to compare it this way regarding the possible
effcts
to humans and devices.

Who wants very strong E-fields and B-fields close to the coil in a living
room?

Best regards
Helmut
 
B

Benj

Jan 1, 1970
0
z said:
People have been hauling wagonloads of coal and firewood for centuries.

Not to mention that little deal with the kite and key....
 
B

Benj

Jan 1, 1970
0
z said:
Popular electronics or some such, way back when had a schematic for a
batteryless transistor radio, which was powered by the signal from a
strong local station to power a separate tuner that you listened to.
(crystal earphones only, please).

Yeah, I remember that. Only if you root through the Tesla US patents
you'll find he already patented the idea back near the turn of the
19th century (going into 20th for you nit pickers). Tesla scoops
Popular Electronics by what, 60-70 years? Everyone yawns and picks
their teeth.

Though I have thought about this. it seems my second floor is right on
the level with the antenna of the local super-power Rock station. You
can just take a diode and a meter and it pegs it all over the second
floor! I keep thinking there ought to be a way to suck some of that
free power out of the air before I get cataracts and go blind.
 
J

Jasen

Jan 1, 1970
0
"NeeBeeNeeBeeNeeBeeNee"
There's some really obscure trivia...

Would that be buck rodger's droid-servant Twiki's 'girlfriend' ?

Klatu barada nikto

Bye.
Jasen
 
K

krw

Jan 1, 1970
0
So, the real question is, would you use it in a real design? ;-)

I did, 35 years ago. ;-)

In college I made a widget that drew a smiley face on an
oscilloscope. I used a quadrature oscillator (two opamps solving the
diffyq for sine/cosine) to create a circle. A shift register and a
few more opamps to size and moved it around the screen for the eyes
(with brows;), nose, mouth, and outline. It worked and made the
kiddies at the engineering open house happy. ;-)
 
M

Michael A. Terrell

Jan 1, 1970
0
krw said:
I did, 35 years ago. ;-)

In college I made a widget that drew a smiley face on an
oscilloscope. I used a quadrature oscillator (two opamps solving the
diffyq for sine/cosine) to create a circle. A shift register and a
few more opamps to size and moved it around the screen for the eyes
(with brows;), nose, mouth, and outline. It worked and made the
kiddies at the engineering open house happy. ;-)


Would you do it in a commercial product, designed today?


BTW, 35 years ago I was transmitting color graphics on a B&W only TV
station. I pissed off a LOT of people! ;-)


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
K

krw

Jan 1, 1970
0
Would you do it in a commercial product, designed today?

Not likely (never did;). There are a lot of things that work, that I
wouldn't do on a commercial product.
BTW, 35 years ago I was transmitting color graphics on a B&W only TV
station. I pissed off a LOT of people! ;-)

Inclcuding the FCC, I bet.
 
M

Michael A. Terrell

Jan 1, 1970
0
krw said:
Not likely (never did;). There are a lot of things that work, that I
wouldn't do on a commercial product.


Inclcuding the FCC, I bet.


No, they didn't find out about it, and as long as a military facility
doesn't cause interference, they basically ignore them. The license was
a 'courtesy' license, with a suggested power level, and no expiration
date. It was a couple arrogant officers that I wanted to show up, for
trying to tell me what I COULDN'T do. They never did figure out HOW I
did it, either! ;-)


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
D

D from BC

Jan 1, 1970
0
Would that be buck rodger's droid-servant Twiki's 'girlfriend' ?

Klatu barada nikto

Bye.
Jasen

lol... :) Buck Roger's is right.

I'll make up a harder one:
Robots "Huey, Louie and Dewey"

Name that movie ****** *******
This goes back 35 years..
D from BC
 
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