Step 5: Thoughts, and Explanation

The ZVS driver is used for a lot of things due to it's simplicity. Your laptop might be using the same oscillator format to run its backlights!

However, in this case, the reason it works is because the ZVS driver begins by oscillating at around 50 - 60 khz. We can't hear it since it's above our hearing range.

Resonance can be thought of like a Pendulum. If you hit a pendulum, it will move forward, and then back. If you hit the pendulum again, right as it starts to swing downwards, the pendulum will travel faster and higher than before. It's very much the same in electronics, just instead of speed and height, it's voltage and current! You can observe it pretty easily with a cup of water. If you shake it just the right way back and forth the water will spill right out of the cup, due to resonance.

Due to this magic called resonance, the voltage swings in the tank (between the 3 + 3 coil and the 2 uF capacitor) are much higher than what the input voltage is. Resonance helps with transmission distance, and also, as a result of how the MOSFETS turn on, they're in what's called Zero Voltage Switching, where they turn on and off when the voltage across them is zero. (meaning, they generate little/no heat due to switching losses). However, due to on-state resistance, they still make a little bit of heat.

ANYWAY, going away from the complicated bits of it, the reason it can transmit power is caused by magnetism. As the coil oscillates, it sends an alternating magnetic field through the air, which is picked up by the receiving coil (and again, due to resonance, the voltage rises upwards!) and thus, power is transmitted through air! The same basic concept is behind radio waves; though, amplifiers are needed to get the audio out of the air, and the frequency is much higher!

I made all of the pictures shown in, though, the transmitter picture is a modified version of the famous Mazzilli flyback driver. (a great, versatile circuit... Used for so much, thanks Vladmiro Mazzilli for this!)

And, one more thing; In another instructable, once I get some protoboard, I'll explain how to make a buck converter. It's relatively easy, and requires just a few parts.

And as a safety note; I'm not responsible for any "oopsies" you make if you decide to construct this circuit. You NEED to make sure everything is connected properly!

If I do somehow end up winning the Epilog contest, I would use the laser etcher to first and foremost, make PCB's. I don't like the traditional way of etching (with chemicals and nasty fumes) and plus, I could additionally sell the PCB's to other electronics enthusiasts for smaller amounts of money, than most etching companies make you pay. I'll try my best to bring this hobby back into the spotlight!

Thanks for reading, and please rate, and vote :)
<p>hey thanks I MADE IT and won prize also ,I am still working on improving efficiency and range. HEARTLY THANKS TO INSTRUCTABLE.</p>
<p>If you have a circuit diagram for this project send me on haroonshabbir@live.com</p><p>Please I'll be waiting.</p><p>Thanks.</p>
<p>Was the circuit diagram ever sent to you?</p><p>Thanks.</p>
<p>i want your design plzzz send me my mail raghav.chandragiri@gmail.com</p>
<p>bro, may i know how did u check whether your transmitter working??</p>
Can u please tell me which type and the gauge no of wire u have used
<p>Congrats to this success! :)</p><p>Please let us know what you changed in your optimising and what the performance-change was.</p>
Hey this is a great Ible! But I cannot read this section. BTW these are the Resistors in the sender schematic.
You gotta click on the little [i] and then the link to the original image link: <br> <br>https://www.instructables.com/files/orig/F6H/9YP2/GUKB3PNB/F6H9YP2GUKB3PNB.png <br> <br>It's 18k and 18k on the top side, and 12k and 12k on the bottom side ;-)
<p>great project and explanation... really helps!</p>
<p>Hi there,</p><p>I made this circuit and I noticed that the coils become really hot when the circuit is on.Is that normal?</p>
Hey guy. I'm very excited to do your project. But I have one question: if the ipod can recharge with 5V, that recharger can be &quot;universal&quot;?<br>Thanks man, your project is so amazing.
<p>What is this black thing on the receiving end?</p>
<p>Awesome project! In the process of trying to construct it....Can you explain what the 1000-3000 uF capacitor on the receiving end is for though? - I don't think I saw that one on the parts list... Can that be any capacitor type, or does that need to be MKP too?</p>
Hi every one. In the receiver, the diode bridge very hot. so doest it have any way to reduce that. <br><br>(im using 0.1uf capacitors)
<p>hey, would you mind sending me more detailed pictures of the build. I'm near at building with schematics and can't really follow it that well. Thanks alberteinstine2012@gmail.com</p>
<p>Hi. Could you tell me please how much energy is wasted from the batteries when transmitting power wirelessly? </p>
<p>what should be the diameter of coil </p>
<p><strong>D</strong> = <strong><u>6.7<em>in</em></u></strong> <em>for the 7ft wire</em></p><p><strong>D = <u>8.594</u></strong><em><u><strong>in</strong> </u> for the 9ft wire<br><br>Disclaimer: If you read further please note that no part of the explanation below is written with the intent to insult anyone's intelligence but rather is aimed at being complete. It does this by not assuming that the reader intuitively knows anything about mathematics whatsoever.<br><br>Summary equation:<br><br></em><em>D = 2 <strong>x</strong> </em><strong>[</strong>[ (Length of wire) / (# of turns) ]<em> <strong>x</strong> </em>[<em>1/(</em>2&Pi;) ] <strong>]<br><br>Derivation of Diameter D equation above: </strong></p><p><em>If you know the total length of the wire L= whatever length you want<br><br>length of wire in ft * 12 = length of wire in inches I will call <strong>L</strong><br></em><em><br></em></p><p><em><strong>L</strong></em></p><p><em>c = <u> </u> <br> number of turns</em></p><p><em>plug c into: </em></p><p><em> c<br>r = <u> </u></em></p><p>2&Pi;<br></p><p>plug r into: </p><p> D= 2r </p><p><em><br><br><u><strong>Conceptual explanation: </strong></u></em></p><p><br>Notice that the length of the wire should be from <em>7 to 9 feet</em>. <br><br>This image: <a href="https://cdn.instructables.com/F6R/QHPS/GUQ4JRDQ/F6RQHPSGUQ4JRDQ.MEDIUM.jpg" rel="nofollow">F6RQHPSGUQ4JRDQ.MEDIUM.jpg</a> <br>Reveals that coil is wound <strong>three</strong> times completely and a <strong>fourth</strong> time including the open ends. <br><br>For sake of convenience let's turn <em>feet</em> to <em>inches</em>: <strong>7</strong><em>ft</em> *(12<em>in for every</em> 1 <em>ft</em>) = <strong>84</strong><em>in</em><br> or if you want 9ft instead: <strong>9</strong><em>ft</em> *(12<em>in for every</em> 1 <em>ft</em>) = <strong>108</strong><em>in</em></p><p><br>Since the coil is wound three times completely and a fourth time with open ends we can approximate that the coil is wound 4 times completely. <br><br>Now you want to take the <strong>length of the wire</strong> and<strong> divide it by the number of turns </strong>it will give you the circumference of the single circle about which all <u>4 turns</u> are wound.<br><br>For 7ft having been converted to 84<em>in</em> we take 84<em>in</em>/4 turns= 21<em>in</em> <br>circumference (which I will call <strong>c</strong>) of the circle with the 7ft long wire is = 21in <br> <strong>c</strong> = 21<em>in</em><br><em>and if you choose to go with the 9ft long wire instead:</em><br>9ft converted to 84in take 108in/4 turns= 27in <br> <strong>c</strong> = 27in<br><br>Now that we have the circumference, we can acquire the diameter. <br>You may recall from one of your classes that the circumference of the circle is &quot;2&Pi;r&quot; if you didn't- now you do. Also recall that I have said above that the letter <strong>c </strong>is set equal to the circumference ( <strong>c</strong> = 21<em>in or </em><strong>c</strong> = 27in ), knowing this we can use the identity of circumference to find the radius: <br><br>Let's start with using <strong>c</strong> = 21<em>in.<br><br>We </em>know that<strong>c</strong> = 21<em>in </em>but also <strong>c</strong> = 2&Pi;r. Now pretty much anyone can see that 1 = 1 or 2 = 2. Likewise <strong>c</strong> = <strong>c </strong><em>thus</em><strong>:<br><br></strong>21<em>in</em><strong> = </strong>2&Pi;<strong>r</strong><br><br>I am hoping you know that the diameter is twice the radius because that's where I got this relation:<br><br><strong>D </strong>=<strong> </strong>2<strong>r </strong>where<strong> D </strong>is the diameter of a circle and <strong>r</strong> is the radius.</p><p></p><p>Divide 21 by 2&Pi; to acquire <strong>r</strong>. <br><br>For the 7ft (or 84in long) wire the radius of the coil is:</p><p> <strong>r </strong>=<strong> </strong><u>21<em>in</em></u> = 3.34225380493<em>in</em> rounding <strong>r </strong>&asymp; 3.342</p><p><strong> </strong>2&Pi;<strong><br><br></strong>Now multiply by two to derive the diameter:<br><br><strong>D </strong>=<strong> </strong>2<strong>r =&gt; D </strong>= 2(3.342)<strong> =&gt; </strong><strong>D</strong> =<strong> </strong>6.684 &asymp; <u>6.7</u><em><u>in </u> for the 7ft wire.</em></p><p><strong><br></strong></p><p>Therefore the diameter is given by:</p><p>For the 9ft (or 108in long) wire the radius of the coil is:</p><p> <strong>r</strong> = <u>27<em>in</em></u> = 4.29718346348in rounding <strong>r </strong>&asymp; 4.297</p><p> 2&Pi;<br>Therefore the diameter is given by:</p><p><strong>D </strong>=2r =&gt; <strong>D </strong>= 2(4.297) =&gt; <strong>D</strong> = 8.594 &asymp; <u>8.594</u><em><u>in </u> for the 9ft wire</em></p><p><strong></strong></p>
<p>Thanks a lot!!<br><br>I was looking for a long long time something like this!<br><br>Can you help me ?? .... In the ferrite toroid we have to wind with 30 turns but I dont know what kind of gauge wire use.<br>Anybody can help me?</p>
<p>Thanks so much for this AWESOME instructable, after much headache I <br>am able to say that I was finally able to get things working. And I'm <br>an absolute beginner so that goes a lot to say about the writer, thank <br>you!! <br><br>I did run into a slight issue though and was hoping I <br>could get some guidance, granted I havent built in the connection to the<br> 7805 and have the tx built as well as the receiver built (caps and <br>rectifier), when I go to measure the dc current at the rectifier I only <br>get .08 on my multimeter... I do however get a full 12 volts at the tx <br>though... Any thoughts? <br><br>Hooked up to 12v 1.8 amp power, <br>everything is identical to instructable (it works, just low low low <br>voltage at receiver end). Only think i notice may be different is that <br>my inductor is made with 26 gauge magnet wire (30 turns) when it looks <br>like in yours you are using some thicker gauge wire. </p><p>Am i just <br>jumping the gun and needing to connect all the way through the 7805 in <br>order to see the full 5 volts? I just didnt want to solder the thing <br>until all tested, figured i would at least get 5v at the rectifier.. <br>unless i'm reading my multimeter wrong (at 20v setting reads .08 max).</p><p>Thanks for any help!</p>
<p>Can I use the powermat receivers like they have at starbucks instead of building it? You can get those for free from the powermat website and saves building that part myself. Will the transmitter work for those?</p>
<p>what use is this comment section if u dnt reply...</p>
<p>why do we require such a high frequency of operation? and what is the diameter of the turns of primary and secondary transmitter?</p>
<p>how will the mosfets get triggered?and what is the operating frequency?and y do we need a high frequency of operation?</p>
<p>bro, can drop me an email ? i want to ask about the project</p>
<p>i made it and its working.....i got 9v without using the 7805...i just wish i can increase the range of transmission</p>
Hello.<br>Can you explain making coil?<br>I cannot do this.<br>Please Can you tell me Radius and Turn of coil.'?<br>Thanks you<br>juekokohtet@gmail.com
<p>Hi, can u help me to troubleshoot my circuit.</p>
<p>ok whats the issue</p>
<p>Hi, my circuit is not working, i have used 2.2uf capacitor mkp similar type. I dont have cro to troubleshoot. </p>
does not it generate emp that harmful to electronics
<p>I dont know why but i cant get it to work. the first Mosfet gets just hot and I dont even get anything to the master coils : /</p>
Hello bro..how did u overcome this problem u faced??
<p>Hello! :) I wanted to ask(I am new to coils) if the <em>3+3 turn coil</em> is like <strong>6 turns</strong> but in the middle a stripped bit, or a <strong>3 turn</strong> coil with a stripped bit in the middle<strong>? </strong>(as it is a bit unclear in the pictures.. perhaps you can even add this to the coil step :D ) <em>Thanks in advance :D</em></p>
How this project makeing for long distance working
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<p>does the transmitter have AC to DC converter and DC to AC inverter? what are the uses for MOSFET and ZENER diode? why use ZENER diode instead of ultrafast diode?</p>
<p>can i buy the kit ??? can anybody please tell me its price please</p>
<p>Hey Guys, I made it! I finally made it, thank you for your information and all the help, i used this for my college project!! </p><p>https://www.youtube.com/watch?v=rdPWNb-70tQ</p>
<p>Where is the ferrite toroid in this schematic? Also, where does the second ultra-fast diode go? It's not in the schematic. Lastly, do we need the filter cap or is it not really necessary?</p>
<p>Hello can you give me the steps of the circuit and the value of the components thanks</p>
can you please give me the steps to make this , I'm lost
Hey, whats the range you achieved? Cause my circuit works but the efficiency drops extremely fast to 0% at a distance of 4 inches or so. Do you know what I could have done wrong?
<p>One drawback to wireless chargers is that they don't achieve great distances. I'm not sure what the maximum distance is for this project, but 4 inches sounds about right.</p>
<p>Great project!Thumbs Up! :)</p>
<p>I have just made this circuit and I ran into a problem.When I connected the circuit to the power supply the wires melted. Any ideea on why that happend?</p>

About This Instructable




Bio: I'm 21, and I have a profound interest in electronics, lasers and Geology.
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