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Wireless Power

Wireless Power
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.

200,000 views and more than 500 comments. Thanks for all your awesome feedback!


 
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Step 1What is it? How does it work?

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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660 comments
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May 5, 2011. 1:19 PMMadScientist101 says:
could you use a 555ic to replace the function genorater?
May 27, 2012. 4:20 AM1710 says:
where i get the circuit?
help me
May 15, 2011. 10:28 AMMadScientist101 says:
why, surely it would do the same job but less options
May 26, 2011. 2:10 PMGoodhart says:
LM555's are power hogs...really !
Jun 12, 2011. 7:14 PMThe nerdling says:
dang i have heaps
Jun 15, 2011. 2:05 PMGoodhart says:
Well, compared to their low powered cousins they are....still they are quite useful.....just not if you need to keep a battery fresh without recharge for awhile. I have a bunch of them too, as I use then for simple timing projects....
Jun 15, 2011. 4:37 PMThe nerdling says:
ok
Jun 15, 2011. 4:59 PMGoodhart says:
Sorry, I just didn't want to discourage your using them...., they can be very useful for the right projects.
Jun 15, 2011. 5:11 PMThe nerdling says:
you didn't disgourage me for using them
Jun 15, 2011. 5:31 PMGoodhart says:
Ok, just making sure :-)
Jun 15, 2011. 5:37 PMThe nerdling says:
ok
May 13, 2012. 2:53 PMdmcintosh3 says:
I've been working on developing a simple DIY inductive charger. I have schematic and low level details in there.

I used a PCB patterned coil for the transmitter/receiver.

https://sites.google.com/site/ddmcintosh2projects/inductive-charger
Apr 23, 2012. 12:37 PMbrenticus23 says:
A few years ago MIT created a system for transferring power wirelessly???? im pretty sure Nikola Tesla created wireless energy in 1891
Apr 20, 2012. 3:29 AMminu.1407 says:
is there any formula to find out the number of turns of the transmitting and receiving coils used for wireless power transmission?
Apr 9, 2012. 4:51 AMnoaddict says:
The MOSFET (IRF520N) heat's up very quick at 12V. Is this normal?
I didn't get it working yet.
Mar 15, 2012. 1:47 PMls1244678 says:
May be someone already noticed. From looking at the picture. The way you connected the capacitor the value will be 0.005uF not 0.02uF. Looks like the value is not that critical.
Mar 6, 2012. 7:52 AMthebfs says:
it doesnt light when u turn it vertical because they recieve power best when they are on the same plane. the primary coil creates a magnetic field. but fields are not even they have gaps and fluctuations. the coils are more sympathetic? efficient parrellel to eachother (the secondary coil accepst the field of the primary better that way
Aug 23, 2011. 4:30 PMwmiddleton says:
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?
Feb 19, 2012. 4:12 AMare_pit says:
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...
Feb 19, 2012. 4:09 AMare_pit says:
hello guys...
i'am want to know...
how the secondary receive volt from primary...
can u explain to me....
thanks you..
Feb 8, 2012. 3:22 PMnzemke says:
Ok so I get everything your trying to do but I'm confused as to what model of rectifier to use? Or if that is even what your using? I picked up a full wave brdge rectifier (GBL005) from Radioshack...is that the correct thing to be using? Thanks ahead of time for taking the time to answer.
Jul 25, 2011. 6:20 AMTNThieding says:
I was very surprised I got this to work! Through the process of building, I was scared of power spreading all over and ruining electronic devices. In the end I was in awe!
Feb 6, 2012. 6:22 PMxenobrik22 says:
hi sir can u give me the exact number of turns of your transmitter coil and receiver coil?? also with the dimension
Jan 3, 2012. 4:13 PMhrishikeshp says:
anyone know a function generator kit like the one mentioned above that is cheap, because the one oin his post is retired, and someone posted a newone, but it is also retired Please help!!!!
Jan 3, 2012. 2:56 PMHamayal says:
Hi Robotkid249, I had just finised reading your article on, Wireless Electricity, and it was very well written, and the eagar to see it for my self, I tried building the model explained, seeing the success before me. It's great to see some one who takes pleasure in expiressing their knowledge with others, such as yourself. I wasnted to implement this concept, into another situation, in which I would like to power a 9V motor DC motor. What guage of wire would I require in the primary and secondary coils to do make this work smoothly, and how would I, in the future, be able to determine this on my own? Thanks, Hamayal.
Jun 20, 2011. 4:41 AMNeMewSys says:
Hi, great article!!
Your 147.7 square wave AC signal generator just retired from the market, are there any alternatives?

How do you know wich capacitor to use to get that frequency? Could you show us the math?

Thanks ;)
Jun 20, 2011. 6:23 PMdanielkim802 says:
there's a newer version of the kit that can still produce the same output: http://www.sparkfun.com/products/10015
Jan 3, 2012. 6:26 AMbvd says:
I am also very interested in this.

Can someone point me in the direction of a kit I could use to generate the 149KHz signal?
Dec 23, 2011. 8:54 AMhrishikeshp says:
hey i checked that link and that one was retired too anybody have suggestions?
Jan 5, 2012. 9:07 PMShogunD says:
http://electronics-diy.com/store.php?sel=kits&sub=function_generator
Theres a possibility.
I haven't tried it yet but I plan on it.
Dec 20, 2011. 12:03 PMmirtunio says:
Hey I have a question, what are the cons if I use a 18 - 20Hz signal and what capacitance should I use on the receiver end?
Dec 27, 2011. 4:26 AMadilvij9 says:
Hi, we want do this project but the problem is we don't know

which type of copper wires to be used, ( i.e thickness of wire)

what are the dimensions to be used please tel the length and breath

1) primary coil dimensions

2) secondary dimensions

and last thing is "how/ can we glow the led about 10 inches from primary coil ".

please help .we really want to do this . please answer ...
Dec 5, 2011. 3:50 PMblob800 says:
Very nice instructable!

I'm interested in learning more about inductors, LC circuits, etc. Did you find any good books on these subjects? (where did you learn that you need a 147.7 kHz square wave AC signal)?
Aug 22, 2011. 9:57 AMM-Taimoor says:
I wanna know that which copper coils these are, are they insulated or wiring copper coils
Nov 16, 2011. 3:22 AMadas11 says:
i interested in this topic.i am an electrical engineering student. plzz any one send me perfect list of equipments my mail id is anjaliswann@gmail.com
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Author:robotkid249
"I am always doing that which I cannot do, in order that I may learn how to do it." -Pablo Picasso "Everyone can be smart. Everyone is given a box of crayons in Kindergarden." There are only two mis...
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