3 ms·

Plates vs. Coils – An alternative approach to wireless power transmission

15 points by luu 11y ago

kwhitefoot 11y ago
>Note that we only need one LED for the inductive coil since there is a loop though the coils, so the electrons can keep going around and around in the same direction and never get trapped. Nonsense. The current in the secondary coil is caused the changing the magnetic field. This cannot keep changing indefinitely in the same direction so the current in the primary that generates the magnetic field must be alternating and then so will the current in the secondary.
- ksrm 11y ago
  The second LED is required for the capacitive example because without it all of the charge would eventually accumulate on one plate. This isn't a problem with the coil as there is a complete circuit for the charge to move around. He is not saying the magnetic field is not alternating (he even says the coil is being driven by a 1 MHz sine wave). The current in the coil is not alternating, because of the LED.
  - kwhitefoot 11y ago
    I see your point, and I was a bit hasty, very embarrassing. That'll teach me to just skim an article quickly.
weland 11y ago
> Q: What is the relative efficiency of the two systems? > A: I don’t really care for this proof of concept. Looks like he'll have a ton of fun after this proof of concept...
somberi 11y ago
From the last issue of The Economist (Edited by me): "..a company called Wibotic that plans to recharge drones (and also earthbound robots) without them having to establish an awkward physical connection with a plug.... LaserMotive, another Seattle-based company, .. is developing a system designed to replenish the batteries of drones that are still aloft, using lasers and photovoltaic cells.. Wibotic’s answer is to use tuned electrical circuits in place of simple transmitting and receiving coils. When such circuits are tuned to the same resonan"t frequency, they exchange energy more efficiently. That permits power to be transferred over distances up to the diameter of the coils, or even slightly farther." Reference : http://www.economist.com/news/science-and-technology/21656134-electronics-has-already-cut-data-cord-can-it-now-cut-power-cord http://www.economist.com/news/science-and-technology/2165613...

15 points by luu 11y ago

>Note that we only need one LED for the inductive coil since there is a loop though the coils, so the electrons can keep going around and around in the same direction and never get trapped. Nonsense. The current in the secondary coil is caused the changing the magnetic field. This cannot keep changing indefinitely in the same direction so the current in the primary that generates the magnetic field must be alternating and then so will the current in the secondary.

ksrm 11y ago
The second LED is required for the capacitive example because without it all of the charge would eventually accumulate on one plate. This isn't a problem with the coil as there is a complete circuit for the charge to move around. He is not saying the magnetic field is not alternating (he even says the coil is being driven by a 1 MHz sine wave). The current in the coil is not alternating, because of the LED.
- kwhitefoot 11y ago
  I see your point, and I was a bit hasty, very embarrassing. That'll teach me to just skim an article quickly.

weland 11y ago

> Q: What is the relative efficiency of the two systems? > A: I don’t really care for this proof of concept. Looks like he'll have a ton of fun after this proof of concept...

somberi 11y ago

From the last issue of The Economist (Edited by me): "..a company called Wibotic that plans to recharge drones (and also earthbound robots) without them having to establish an awkward physical connection with a plug.... LaserMotive, another Seattle-based company, .. is developing a system designed to replenish the batteries of drones that are still aloft, using lasers and photovoltaic cells.. Wibotic’s answer is to use tuned electrical circuits in place of simple transmitting and receiving coils. When such circuits are tuned to the same resonan"t frequency, they exchange energy more efficiently. That permits power to be transferred over distances up to the diameter of the coils, or even slightly farther." Reference : http://www.economist.com/news/science-and-technology/21656134-electronics-has-already-cut-data-cord-can-it-now-cut-power-cord http://www.economist.com/news/science-and-technology/2165613...