About Wireless Power Transfer

I talk about magnetically coupled wireless electricity technology. Lots about inductors, Q factor, AC losses and what this all means for practical implementations of wireless power transmission.

Main article is here: http://www.vk2zay.net/article/253

Circuit of demo TX/RX here: http://www.vk2zay.net/article.php/262

Category:

Science & Technology

Tags:

• vk2zay
• wireless power transfer
• electromagnetics
• induction
• inductors
• q factor
• transformer
• circuit theory
• witricity
• tesla
• chalk and talk

[iceman77706]

How do you calculate/ whats the equation for the coupling co-efficient (k)!!!!!!!!

[vk2zay]

@iceman77706 You can calculate it from EM theory, but it is dependent on basically everything, so it is usually just measured using mutual inductance.

[MrStudent1978]

In other words my question is whether the resonance has to do something with transformer design?

[vk2zay]

@MrStudent1978 Resonance and low losses allow reasonable efficiency when the coupling is very low.  Typical power transformers have excellent coupling between the windings. Without resonance you'll see very little power transfer and without high-Q the efficiency will be terrible.

You can check it yourself by doing the maths, or building the circuits - or both. :)

Either way, it is a fun experiment and I encourage you to try it for yourself, I learnt a lot about the physics involved.

[danewwittig]

I'm kind of a rookie at electronics, but how come the LED can take AC?

[vk2zay]

@danewwittig LEDs are like any diode, they won't conduct in the reverse direction when the applied voltage it below their reverse breakdown voltage. The LED is actually rectifying the RF and is glowing during less than one half of the cycle times, it is also clamping the amplitude of the voltage across the secondary coil. This isn't a typical or very efficient circuit really, but just the simplest that would work. Directly connecting the LED across the tank is actually very bad for its Q.

[eequestion]

Can i substitute antennas instead of inductive coils. If yes what do i consider in order for this circuit to work?

[Hrishikep]

cool it helped with my school project, thx

[ghesil]

very good and informative, thanks for sharing

i was wondering what will happen if i have let's say a sheet of steel parallel to the primary, wouldn't that create a current in the sheet of metal that is basically a short (similar to inductance cookers let's say :) ). and if not why not.

[clodester]

other than electric toothbrushes, are there other examples of cheap wiresless power/inductors around the home which can be cannibalized?

[bridgetroll9]

Everything is wireless in nature. No cord exists between the sun and a solar panel. Gravity is not powered by energy from a cable. You really believe the heat on your skin actually traveled from the sun to your face? It comes from the same space in which it appears.

The wireless process we use today does not exist in nature. Which makes it a perversion of nature.

[luarkas]

Wireless is great! but always think about biological effect on humans, living organisms and Earth electromagnetic equilibrium.

[MrHeffernan11]

Hey Mate Im Very Interested in what you got to say But i Find it Hard to Follow at times because of the Lingo you use to Explaine and the drawn symbolism you use to Show diagram about the Power flow So if ,If you get the time Mate can you Plz Make a tut Explaining the Words you use to Explain things and what the Symbolism you use

[SHIMMY956]

Can power transfer be harmful to living tissue?

[coldfusion12]

Great instructional video, really enjoyed it, thought provoking!

[MrGangeticus]

I pray that this is not a stupid question. :) According to Faraday, the magnetic field is created around the wire, perpendicular to the direction of flow of current, right? So, what happens if the wire is coiled unto itself? Does the field follow the first winding or does it follow the general flow of the current? I hope I make sense. Thank you for your answer. BTW, the video is amazing!