# Making Self resonating coils for wireless electricity transfer How to do

• mnnittronix
In summary, the conversation discusses making self-resonating coils for wireless electricity transfer, specifically for a project to glow a 60W bulb at a distance of 2 meters with over 40% efficiency. The conversation mentions using a variable tuned circuit and adjusting it for maximum output, as well as using a small capacitor to fine-tune the resonance point. There is also a suggestion to look into yagi antenna design for directional control. However, the feasibility and safety of transmitting 60 watts of power through the air is also brought up.
mnnittronix
Making Self resonating coils for wireless electricity transfer ! How to do @@

Dear Friends ,
I would like to make the wireless electricity project as done by MIT team.i am bit confused about how to make the two different coils resonate at the same frequency ??

Usually, you make one of the tuned circuits variable and adjust it for maximum output.

Do you have a circuit diagram of what the MIT team were using?

Here is an instructable i found for a slightly more simple approach:

http://www.instructables.com/id/Wireless-Power-Transmission-Over-Short-Distances-U/"

Also, this website has some information on resonant coupling:

http://www.wirelesspowerconsortium.com/technology/resonant-coupling.html"

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If you have two coils that are supposed to be identical, it is difficult to wind them to be exactly the same because you might miscount the number of turns.

So, you wind one of the coils with slightly too many turns and start removing turns until you get maximum output.

One refinement to this is to have a small capacitor and put it across the coil each time you test it. If the capacitor makes the received signal worse, you can remove another turn. If it makes the signal better, you have already passed the resonance point.

thanks for the replies... i need to make a system to glow a 60W bulb with a distance of 2meters and have more than 40 percent efficiency for this project..

can u please specify me what will be the dimension of coils and other circuit parameter... a rough idea if not exact...

thanks a lot...

I don't think you could do this.

A solenoid makes a very poor antenna and little of the power in it is radiated.

Of what is radiated, a small portion of this is intercepted by anything placed 2 M away.

I don't have any figures on this, but if I had to guess, I'd say you might get 1 % efficiency if you were lucky.

Tesla coils use such techniques, but at much closer spacing so they are magnetically coupled.

If you had two microwave dishes at that spacing and facing each other, you just might get a lamp to glow at the focal point of the receiving dish.

any more help ?

mnnittronix said:
thanks for the replies... i need to make a system to glow a 60W bulb with a distance of 2meters and have more than 40 percent efficiency for this project..

can u please specify me what will be the dimension of coils and other circuit parameter... a rough idea if not exact...

thanks a lot...

40% @ 2 meters! yikes! You would deffinately need some kind of directional control over where your em field would be propagated, try maybe looking at yagi antenna design? What you are trying to do is a pretty tall order, sorry I couldn't help more.

I'd be scared to have anything remotely close to transmitting 60 watts of power though the air..