wireless power.pdf

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Wireless Power

Quarterof 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!

Tunable Diode Laser

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About This Instructable

Posted:

May 6, 2009

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robotkid249

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2/13

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/

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 o f 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.

Related

See MoreSee More

GroupGroup GuideGuide

Wi-Tricity (Wireless

Electricity)

by howtowithmanish

I need your help. IPT

(Inductive Power Transfer)

by puffin_juice

Wirele ss Power

by halo456456

Low-Power Wireless

Charging

by gripen40k

Wireless L E D

by neelandan

Step 1Step 1


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The primary coil creates a magnetic field, when another coil is placed near it, energy wi ll be

induced into it.

Be in mind that i could not ge t a hold of a 0.02uF capacitor so i used two 0.01uF

capacitors connected together.

Creating the Primary Coil

The pr imary coil uses magnet wire, which is easy to get at RadioShack.

http://www.radioshack.com/product/index.jsp?productId=2036277

We will use magnet wire as the material for our coils.

Step 2Step 2


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Next we need something to create the 147.7 square wave AC signal. I saw videos on youtube like

this one. http://www.youtube.com/watch?v=SSgo_N-5JOg Which uses a function generator. Sadly,

these cost a lot of money, so i wanted to get a low cost one, that still did the same thing, just not as

high of a frequency. This http://www.sparkfun.com/commerce/product_info.php?products_id=9002

is great for what i needed. Cheap and simple.

This will be the main board to create the signal.

By using a pencil or nails on a 2 x4 and your magnet wire, you can make a pretty good coil. I did

about 30-40 turns, depending on the thickness of your magnet wire. Magnet wire has a very thin

coating on the top of it. To get this off you can light a match and put the magnet wire in the flame

for a few seconds. Take the two ends of you coil and put it into the function generator on the top

two screw terminals, one in each terminal. Polarity is not a problem right now because the signal

will be AC. Now place your 0.02 uF film capacitor in parallel wi th the terminals you put the wiremagnet ends into. Turn the function generator on and use your multimetter to get it to somewhere

near 147-149 kHz by turning the potentiometers. Make sure the switch on the left of the board is

set to square, and your good to go. The top to terminals will allow for an AC signal.

The Secondary Coil

This circuit is one of the simplest you can ever create. It is composed of magnet wire coil but

smaller like the primary, a 0.02uF

capacitor also like the primary, and some leads you can attach things to. For LED's the circuit

looks like that. Yet, for powering your iPod and other devices that use DC power you need a diode

bridge, or rectifier which can turn AC into DC to power your portable device. Take a look for

yourself that the secondary coil has an AC output which will only power LED's.

Step 3Step 3


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Testing Wireless Power Through Different Materials

Yes, I decided to go a little further because of the response that I received.

You were always told as a kid, water and electricity DO NOT MIX, and that may be true, but not with

wireless power. I tested this in water. No, I did not get shocked, but you may. NO! You will not I

promise. This Step shows that this type of wireless power can pass through almost anything,

except metal, I know, I was sad when i found that out. I mean, for a practical use, many people

have desks made of metal where the coil is. This is not good, but I digress, we must move on.

Water! I mean who would think that this kind of technology has this kind of potential! It works that

same exact way as if it was not in water. It is in a plastic bag as you can see. Only to protect the

electronics. Unlike WiFi which is can be weakend by walls and other things, Wireless Power is not!

Step 4Step 4

Step 5Step 5


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Circuits

These three pictures I have posted are of the circuits that I used. I have also posted a third picture

of a theoretical circuit (has not been tested so i am not sure if it works) which turns the

received energy into DC so you can hook it up to your favorite electronic device, iPod, cell

phone...

Primary Coil-The function generator is the Main circuit of the primary, but you can easily buy it

from the link posted earlier. Alon with the magnet coil.

In the Secondary Coil Diagram, the only capacitor is a 0.02 uF as I explained why.

Data

The power coming directly from the function generator to the coil: 110.5 mW.

Maximum power efficiency achieved is 42.2%. This is a very respectable power efficiency

considering a limited budget and short experimentation time period.

The following chart is a visual representation of the above data points.

The following graph represents how the power output of the secondary coil was effected by

efficiency at certain distances from the primary. At three inches, the current technology outputs a

value that is very minute and is not efficient enough to power much of anything. However, at zero

inches, the power output is very capable of achieving the goal in the engineering objectives.

Step 6Step 6

Step 7Step 7


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Extra Hardware

I have now added a AC to DC diode bridge which converts AC to DC. Then i added a Joule Theif

to the diode bridge, which is a very simple circuit that can amplify input power (the Dc voltage from

the diode bridge). http://www.youtube.com/watch?v=gTAqGKt64WM

This allows the LED to be lit when its father away from the coil, because the voltage going to the

LED is higher. It is now able to power DC devices.

Extra Information

I have shown you the basics of transmitting power wirelessly over short distance. Now it's your turn

to make your own and comment on how your made your Mat and what you used it to power.

-If you have access to a larger function generator you can use that in the same way we used here.

-Then you can also use the 555 timer, which can create the same kind of signal, but is a bit more

complicated.

-So for all of the comments, here's some more info about about how this system functions.

With my size coils as seen in these pictures, based on how well you can tune the frequency, your

looking at an efficiency range of about 70 to 85%. The led in the secondary coil, starts to fade

when it is about 2 inches away from the primary. At about five inches, it is pretty well dark, but at

four inches it is still a bit lit. If the coil is turned vertical, the led is dark. Please comment if you know

why it is not bright when the receiving coil is vertical.

Step 8Step 8


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Rich EditorRich Editor Add ImagesAdd Images PreviewPreview PostPost

Oct 22, 2012. 8:22 PM ReplyReply

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Oct 19, 2012. 11:24 PM ReplyReply

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Sep 28, 2012. 5:02 PM ReplyReply

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-Here's some variables that may change the outcome:

Wire gauge - 22

Amount of Wire - 40 feet

Capacitor value in primary and secondary - 0.02 uF

input voltage - around six volts; hint; i used a irf520 mosfet to amplify the power input

from the function generator, which increase the secondary voltage tremendously. I'l

post some pics soon.

usage of secondary coil - a voltage meter should be used first to see if there is any

voltage; then you can attach an LED. I've gotten 5v from the secondary with my circuit

from a 6.3 input voltage to the primary

Step 9: List of Components

Plastic Project Box

http://www.radioshack.com/search/index.jsp?

kwCatId=&kw=project%20box&origkw=project+box&sr=1

Function Generator

http://www.nuxie1.com/guides/fungen-v2-kit.html

Breadboard

IRF510 or IRF520 MOSFET0.02F capacitor x2

Magnet Wire (Gold for Primary, Red for Secondary)

http://www.radioshack.com/product/index.jsp?productId=2036277

L.E.D.

Wall Power Converter 9-18VDC

This helps us reduce spam.

1-40 of 675 Next

ehabcharek says:

is it possible to connect the primary coil directly to the power source and the secondary coil directly

to the (for example) LED?

also, is it possible to use metals other than copper?

agis68 says:

whata you did there was also well descibe it by Tesla itself. But well you did it to remin us this cheap

and safe energy transfer. Now my question.How did you make it to give this squire with smooth

corners form of your coils. How many turns is the primary and how many the secondary.

thank you for sharing

alinnekersays:

What's the calculation that can be used in the experiment?

We have a "be nice" comment policy. Please be positive and constructive with your comments

Type the two w ords:


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Jun 3, 2012. 11:10 AM ReplyReply

alinnekersays:

Calculations of electromagnetic waves.

jose1522 says:

Hi guys! I was looking for an alternative for the Frequency Generator Kit since its not available and I

found that a astable circuit with a 555 timer can do the trick; however, i'm not sure about the

Capacitor and resistor configurators... I used an online calculator to obtain a configuration close to the

147.7 Khz frequency and it turns out I can get 146Khz with a 470 ohm R1, 47 ohm R2 and 0.01 micro

farad C . Can someone double check the math for me? Thanks!

jose1522 says:

Sorry, another correction. R1: 33ohms, R2: 470 ohms.

jose1522 says:

I just reallized that with a 33 ohm resistor instead of the 47 ohm one I get 148Khz frequency.

Still, can someone double check it?

freakqnc says:

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 automotiv e 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

are_pit says:

hello guys...

i'am want to know...

how the secondary receive volt from primary...

can u explain to me....

thanks you..

DonEMitchell says:

Hi are_pit,

There is a common mis-conception that the power is transfered by induction.

This is not true. The power transfers by coupled magnetic resonance --the magnetic

equivalent of Tesla's high-voltage resonance.

Check my time-line I'm still working on...

http://portal.groupkos.com/index.php?title=Near_Field_Resonance_Time-line

The coupling phenomena is more akin to nuclear magnetic resonance than common

induction.

One company is already making a power-pad wireless power charger for electric vehicles.

Google the quoted term "wireless power transfer" for starts. There's lots of background, more

almost every day.

Another company already announced a cell-phone wireless power antenna. See my wik i

above... main page, top of the top-fifty list... Electromagnetic Coils.

Have fun... run the background... there's are hardly any experts out here yet!

DonEMitchell

Schobersays:

There are a couple of things you should know before I begin to explain how this works.

Firstly, when electricity runs though anything (not just wires) it creates a very very very small

electromagnetic field.

Secondly, this electromagnetic field has a spin around the conductor relative to the direction

of flow ofelectricity.*


10/13

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Jun 21, 2012. 9:35 PM ReplyReply

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Thirdly, this spin is amplified by proximity to other conductors.

Fourthly, flow creates spin and spin creates flow.

Now that you know those four things I can begin to explain.

The primary coil is a coil and not just a solitary wire because the voltage being put through it

does not create enough ofan electromagnetic field to transmit power. So when the wire is

looped around next to itselfit acts like one big wire and creates a larger field than that of a

single wire.

Once the field has been increased from a few micrometers to a few inches in this manner

you can start to receive power. Due to the spin created by the field any circuit (electricity

has to have a place to flow) placed within it will "resonate" this spin and begin to carry

electricity on its own almost as if by magic.**

But this only goes so far. This field, while stronger than before and able to generate

electricity, does not have quite enough power to be able to run a device receiving power

through a single wire. And so it must be passively amplified (through another coil) before it

can be sent to the components you are trying to use.

Once amplified in this manner there is enough voltage flowing through the receiving coil to

power the device or components it is attached to.

PS This is a relatively basic and general explanation of how this works. A more detailed

description ofit can be found almost anywhere.

Wireless Energy Transfer

Electromagnetic Induction

Make Presents: The Inductor(Watch the whole series of Make Presents videos they explain

almost all of the basic electronics components)

*Use the Right Hand Grip rule to determine direction of spin. Hold your right hand up in a fist

with your thumb up. Your thumb represents the flow of electricity down the wire. Your fingersrepresent the direction of spin around the wire.

** This is the principle behind an Electro-Magnetic Pulse (EMP) the pulse creates so much

voltage within the target's circuitry that it overloads all ofthe components, and destroys any

form of magnetic storage.

The Maker Now says:

Hello,

I tried the links you've provided for the Function Generator but the links say that they are not

manufacturing the products.

Is there a way to get the project done without the generator?

And how to make the secondary coil?

ausam says:

Hi, I have a simple question. Do I need the function generator to produce AC square waves of

approx.147 frequency? Can I just simply connect the primary coil to a power outlet or any other

source of AC current? thanks.

PS. (pleeeaase do answer. i'm doing this for my school science fair)

akipfersays:

hi, listen to me, i recently bought a mouse, wireless mouse, but i paid 6bucks tops

(dealXtreme) this mouse, more precisly 'http://www.dealextreme.com/p/wireless-optical-mouse-9?

item=2' no quotes

I want to make it fully wirelesswith no need of batteries, this mouse can't hold up so much, 2 fresh AAA baterias, 2, maybe 5 days

top, and the baterryes are dead...

can i do that?

won't harm my PC? i would put the large coil 'maybe under the table, wooden table, or make a case

for it, tiny , so i put the mouse on it, 24\7 on wireless'

can i do that?

mouse uses 2 AAA bateries, 3V...

sujithZissays:

Hey guys .....im making making the instruct-able

http://www.instructables.com/id/Wireless-Ipod-Charger/?ALLSTEPS#

and i am having small doubts ... .......... .. .... ........

desperately needing experts advice's

MadScientist101 says:


11/13

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could you use a 555ic to replace the function genorater?

robotkid249 (author) says:

Yes, but it wouldn't be efficient...

1710 says:where i get the circuit?

help me

MadScientist101 says:

why, surely it would do the same job but less options

Goodhart says:

LM555's are power hogs...really !

The nerdling says:

dang i have heaps

Goodhart 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 ofthem too,

as I use then for simple timing projects....

The nerdling says:

ok

Goodhart says:

Sorry, I just didn't want to discourage your using them...., they can be very useful for the

right projects.

The nerdling says:

you didn't disgourage me for using them

Goodhart says:

Ok, just making sure :-)

The nerdling says:

ok

The nerdling says:

how can i do it?

dmcintosh3 says:


12/13


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I've been working on developing a simple DIY induct ive 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

brenticus23 says:

A few years ago MIT created a system for transferring power wirelessly???? im pretty sure Nikola

Tesla created wireless energy in 1891

minu.1407 says:

is there any formula to find out the number of turns ofthe transmitting and receiving coils used for

wireless power transmission?

noaddict says:

The MOSFET (IRF520N) heat's up very quick at 12V. Is this normal?

I didn't get it working yet.

ls1244678 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.

thebfs 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

wmiddleton 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?

are_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...

nzemke 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.

TNThieding 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!


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Feb 6, 2012. 6:22 PM ReplyReply

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xenobrik22 says:

hi sir can u give me the exact number of turns of your transmitter coil and receiver coil??

also with the dimension

robotkid249 (author) says:

Great!

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