Instructables
Picture of Wireless Power
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Quarter of a million views, thanks everyone!

The power cord, I know you hate it. Sometimes, you just want to cut it apart! Well say goodbye to your power cords, because with the power of inductive coupling your device will not need to be connected metal to metal. Seemlessly your device can be charged!

This instructable will show you the basics of creating your own cheap and easy wireless power mat, which you can use to power your device through the air!

New Update: complete list of components.

Check out my new project on sending a balloon into space!! 
http://www.instructables.com/id/My-Space-Balloon-Project-Stratohab-Success-High/


 
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Step 1: What is it? How does it work?

Picture of What is it? How does it work?
A few years ago MIT created a system for transferring power wirelessly. They transmitted power over a two-meter distance, from the coil on the left to the coil on the right, where it powers a 60W light bulb. Back in 2006, this was a pretty cool thing. You can only imagine what the implications of something like this would be. Well, unlike most of us, we do not have the time or material goods like MIT has. So i have made this simple and easy to follow Instructable, so all of you good people can experience the joy of wireless power.

Inductive Coupling uses magnetic fields to transfer power. There is a primary coil, which generates a magnetic field. Then there is another secondary coil which is composed of a capacitor and a coil, the capacitor creates a resonant circuit with the primary and secondary coils. Seem easy? Well, before publishing this instructable I found many useful and a lot of non-useful info on the subject.

In my research I found, that to transfer power in very complicated. Once i did it I found that you do not need to go to MIT do do this sort of stuff. With a little electrical know how, this is easy.

It all starts with the transmitter. This transmitter needs to create 147.7 kHz square wave AC signal. Let me take a minute to explain this all. Level one on the frequency scale is Hertzs, then there is kHz, then MHz. MIT used a 10 mHz wave to drive there coils, but for this we will be using a 147.7 kHz signal so it does not get too complicated.

The secondary coil has a 0.02 uF capacitor. This will allow the two circuits to be coupled therefore, transferring power efficiently. The 0.02 uF capacitor is used only for this frequency, and the value of this capcitor will change depending on the frequency.

The primary coil creates a magnetic field, when another coil is placed near it, energy will be induced into it.

Be in mind that i could not get a hold of a 0.02uF capacitor so i used two 0.01uF capacitors connected together.

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I see a heck of a lot of wire for something supposedly 'wireless' .

could you tell us the formulas required to calculate the values to prepare the primary and secondary coils and also the ratings of the components used to construct the required circuit to achieve the specific output(i.e voltage and amperes).

railgunfuzz5 years ago
Couldnt you use a crystal resonator on the secondary coil?

Over doing it! Quartz resonators are in the kilohertz range.

06-04894 years ago
can the range be increased?....how?...is it posible to increase it to about 1meter or longer?.
yes the higher the frequency the longer the range

Also, the thinner the effective cross section of the wire, do not go overboard or your skin effect will fry your wire.

Websteria4 years ago
Is there a way to do this with a smaller amount of coil?

Yes, it can be accomplished in the same manner by using the same ratio of wraps of wire (internal coil/external coil) (make sure it is insulated wire and away from anything flammable as sparks may still ensue (and DO NOT plug a circuit like this into a wall or anything above a 1.5v battery))

wmiddleton3 years ago
hi, i'm liking this small DIY project :)
umm, what do i need to put in my mobile phone, mp3 etc. to charge it from the coils?

You should be able to find the information by removing the back panel of your cell phone and observing the sticker on the battery, it should say something like "6.5v 600mWh" the second number is how much your battery stores, the first is the voltage it stores at. Though, you shouldn't really try to charge your phone in that manner, you will end up frying your circuit board and possibly over charging your battery (not fun, lithium burns require hospital treatment.)

hello wmiddleton!!!
are you found the solution in your case???
my case like your case...
i hope u can share u solution to me...
thank you...
MasoodZ1 month ago

Great,

wonder if I could make one too

MayankD1 month ago

Hello admin,

Your blog about this wireless power transfer is quite good for basic model but it has limitations of 3cm of induction area.

Research of Mit that you told is not complete ,Mit used a resonating coil prepared of large capacitors at both ends of inductive coil that produced a resonating frequency for large inductive coupling.

So,if you know further about it let me know .

vick952 months ago

hey admin can you contact to me in gmail, i wanna know something..my gmail is - vickybisht1995@gmail.com

sbammigatti2 months ago

Hello there. Awesome project.

It would be really helpful if you post the circuit schematic.

Thank you.

evictor25 months ago

Aren't the exposed wires dangerous because AC is passing through them? How can this be insulated safely without affecting the resonant properties of transmitting and receiving coils?

The power is so low that it won't hurt you.

Thanks for the reply. Would that still be the case if I were to build a unit capable of powering a 40W 120V light bulb wirelessly? Would the conductive socket of the bulb and other exposed wires need to be insulated then?
asrivastava105 months ago

Well you can use OP-Amp to create a square wave of desired frequency, just google it, its very easy to make as it looks from the diagram cz I have never made it myself just studied it as a part of my electronics course.

You can do the same using 555 timer though its a bit less easy as compared to opamp one.

js126 months ago

Hi! It's possible to make a transmitter in AC signal? not continue. I'm so interesting in this.

Thanks a lot.

fbianzon6 months ago

That is awesome good idea only need loop of coil divert into electrical energy. Thanks for the share.

shrawan988 months ago
where i get the circuit?
help me
shrawan988 months ago
where i get the circuit?
help me
morningshofi8 months ago

how to make the primary circuit?

Ajith19958 months ago

how much distance will this take place....i want to increase the distance.. what is the method

dkimbril9 months ago
Does anyone know what the device is that is connected to the ground on the MOSFET?
freakqnc2 years ago
Quick question for anyone willing to pitch in. I am trying to use induction coupling to transfer power from a coil to another because I only need a contactless connection. I am using this in automotive to transfer 12v from standard light wires.
I can't find any simple schematics or info on how to accomplish that though looking at info I did find I should be able to use just 2 coils and perhaps just a couple condensers and resistors... I'd appreciate if anyone could be so kind to point me in the right direction! Thanks in advance! :D

I'm looking to do something similar, I'm needing a 14+V, 2-5A power transfer, using induction like this. I do in a way understand how this works, however I have no idea how to get a fairly large power transference. Everything I read is 3-5V, >500ma, not even close to what I could use =(

<500ma ***

ThatCatMan10 months ago

Also, if you think about it, this wireless power system is very similar to the way a simple transformer. Power goes into one coil, creates a magnetic field, and it passes to the other coil, but to a higher output.

ThatCatMan10 months ago
Hey robotkid! I like the Instructable and I had an idea for you. I don't know if you know about Electrostatic levitation, but I have seen work done where you can move a metal ball through a small space with magnets making it seem to "levitate." If you could do one of those, you could combine that with this wireless power in a larger scale to make something in a small sphere, as long as the magnetic field doesn't interfere with the wireless power, to make a free floating, free powered, circuit to move around in an open space. A nice challenge for you, I hope?
Like, if you could have a micro-camera inside a "globe" with a rotating center bar, all controlled with infrared signals, you could control the zoom and direction with an IR-Remote, while controlling the position with the above electromagnet control. A free floating camera. But then, I think the electromagnets to "levitate" might cause problems with the servos that turn the camera. Just a little idea I know wont work.

Oh I made a mistake. It is not electrostatic levitation, but instead Magnetic levitation.
The same concept that holds a levitating globe in mid-air. An electromagnet controlled by a circuit that keeps the object floating.
claudiopolis10 months ago
I see nobody here worrying about EMI. Electromagnetic interference will affect audio/video/PCs a lot. Shielding can not be used, it would hamper the power output. So we're left with a "dirty" (in EMI terms) power supply with less than 50% efficiency, for getting rid of a 3 inches long cable. I'd say wireless charging still has a lot to evolve.
gospina1 year ago
Hey guys! I'm planning on trying something like on a new project, but I'll need someones help who knows this area of study. What degree is related to this or what field of study is this related to? Also for anything wireless and electrical I guess.
zseys1 year ago
can i charge my phone with this? it has the backing to accept the charge.
how may i create 147.7 kHz for Tx without using signal generator.have any efficient circuit diagram of ur project.i need it.
gnimrezt881 year ago
Hi, may I know what component is used in the design for the primary coil? (The one connected with function generator and dc jack, voltage regulator?)
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