Wireless Power

Step 8 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.

-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

Comments

[wmiddleton]

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?

[lee_y_l]

Can anyone give some advise on how the IRF520 mosfet should be connected to the circuit? Thank you.

[robotkid249]

New circuit diagram, yay!

[lee_y_l]

I've tried with the new circuit diagram but seems like not much difference on the o/p power of the receiving side. Can i know how much voltage (DC?) are you feeding the MOSFET?

[robotkid249]

12 VDC from a wall plug. Make sure everything is hooked up, because you should see a major jump into primary coil current.

[Websteria]

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

[redbloomer]

if you will notice..the two 0.01 uf caps are in series.. and it reads us 0.005 uf not 0.02uf.. i think he have done it as "trial and error " on his experiment.. and the description of the number of turns for the primary and secondary is not properly discussed..and i think on step 6 , he includes a joule theif because he wants to have a larger voltage output that can be up to 5 volts.. actually it only reads 5 volts when it doesnt have a load. on his experiment he only have a led that only works for just a couple of miliiamps..eheheh... sir if you actually wound the primary and secondary coils a couple of hundreds of turns of wire . you will desirably achieve the voltage and current output you want..

[tanvisarin]

m wrking on a similar circuit for a mobile battery charger ...in dat i neeed 2W power...which m nt getting...my result so far is 5v with 100 ohm resistance 1.e only 250 mW....please help me ....itz very urgent could you please mail me [e-mail]

[diametal]

I have  a Q....

How can i figure out the number of coils?

I guess there is an interrelation of this...

But I couldn`t find it. 

I am going to use a 24AWG wire for my lab.

But I don`t know how to calculate the inductance value of the wire

please..!! somebody helps me out.... 

[06-0489]

can the range be increased?....how?...is it posible to increase it to about 1meter or longer?.

[gato667a]

yes the higher the frequency the longer the range

[gato667a]

i dont know what to use for a generator so am going to use my ps2 generator,it should work and i think probably why it doesnt work verticle is because the way u put the wire together their on top of each other not next to each other,well i think so cuz in all my classes i always see the wires of coils next to each other and not on top of each other.

[pipponum1]

the led doesn't light because the two coils don't have the same polarization. moreover the maximum magnetic field is in the middle of the coil (if you try to take the secondary coil next to the border of the primary coil you will see that the range is decreased).
One question: you said that you needed a 0.02uF capacitor so you put together two 0.01uF capacitors. But in the picture it seems that the capacitors are put in series, so the total capacitance is 0.005uF, not 0.02uF. Is that true? are they in parallel?
Moreover do you have an oscilloscope? it would be nice if you post the shape of the received wave.
Thank you

[marzban123]

what is the power output on the secondary coil? could one use a 5v regulator to charge an ipod or is there not enough power. how does one adjust the power output of the function generator?

[kikiclint]

The power depends on how efficient your circuits are at transmitting the power.   The volts will be a function of the ratio of turns in your primary coil and your secondary, as well as how close to resonance the primary is ringing.  which direction the  coils are facing and how far apart they are will also factor in on the power. 

[SalemSnaKe]

Nice project, I have a computer mouse that works on this technology thus beeing wireless but having no bateries, I bought it like 5 years ago, it`s good to know how it works

[samr37l]

Sorry to ask again but I'm having some some trouble with the 555 timer circuit. I'm using the astable 555 timer circuit but when I plug it into the coil the 555 timer gets really hot and the frequency goes way off (like it changes from 150 khz to 110 than back to 170 and then to 150 again). If anyone has any ideas please help me, and if anyone has any better ideas on how to make the 555 circuit can you please send it to [e-mail]. Thanks a lot, SAm

[brokengun]

The primary coil probably is drawing too much current for what the 555 can stably provide. It is a good idea to use a power transistor or something for the coil that way your don't draw your power from the 555 it's self. Also, because of the heat the current is making the 555 will mess up. It does it with temperature drift.... that is why it's probably better to get a function generator that is more resistant to this. It is a common problem, does the same thing with cold too.

[samr37l]

do you have a good circuit to do this? like how could a put in the power transistor cuz I already tried that and I blew a 555 timer. Thanks, Sam

[wolfkeeper]

It's probably a voltage thing. The point of this system is that the sender coil has to ring strongly- you're probably overloading the 555 timer, because the volts on the ringing coil are tens of volts, in both directions, even though you're only feeding in a few volts from the oscillator. I doubt the 555 timer can take that. At the very least you need a transistor or two to decouple the timer from the coil.

[brokengun]

I don't really have a circuit, but you just use it like any old transistor. A power transistor is rated for more current. Basically just hook up the output of the 555 to the base of your transistor, then have the coil power hooked up to the other two ends of the transistor. In this way the transistor acts like a switch and will pulse the coil on an off but the power transistor will take allow for more current to be drawn.

[railgunfuzz]

Couldnt you use a crystal resonator on the secondary coil?

[gabe94]

I am completely confused at what you mean about making either of the coils. Can you go into more details? I am kind've short on budget and can't afford to make several and test them.

[toby5150]

Magnet wire is used in many types of transformers so can be stripped from old equipment and i beleive that old microwave ovens are cheap sources of magnet wire (coated in insulating material so that when 'coils' are made they don't just short circuit)

[gabe94]

I am not sure how to make the coils, it wasn't very descriptive. Also i am not sure how to set up the function generator kit

[tanmanknex]

you stick four nails in a board and wrap it around, over and over until it's the right size. then you pull some out and lift the coil off. wrap a bit of tape around each side and you're good to go!

[drchoc]

Hey your LED is in parallel to your circuit, in fact if you set it up that way you don't really even need the capacitors. I am beginning to question whether you are using a resonant coil; you said you used .02 uF but your capacitors are in series making the capacitance .005 uF. What I see here is either a simple air core transformer, or an extremely lucky resonant coil. I suggest you try and measure your inductance and then calculate and see if you are making a resonant circuit. Could you post some dimensions for your coils? and what gauge you used? Thanks, and nice job! Dr. Choc

[kurzundknapp]

Nice little project! Really simple...
To the reason why it doesn't shine when the receiving coil is vertical to the other: As you already said the principal concept behind this is the magnetic coupling. So there's a so called Lorentz' Force involved, which acts only on vertical directions. In detail: The moving electrons in the outer coil are inducing a magnetic field vertical to the way they travel. This field works mostly inside the coil and stands vertical to the plane of the coil. Then the magnetic field itself begins to move the electrons in the wire of the inside coil, which results in another current. So if one of the coils stands vertical to the other the Lorentz' Force can no longer move the electrons and so there isn't an electrical flow anymore.
Visit http://en.wikipedia.org/wiki/Lorentz_force for more information on this and don't forget the three-finger-rule if you're using this concept ;)
Greez

[rajsekhar291]

How to connect the LED's and the capacitors to the secondary coil.