Making a Wireless Charger (4)

7/25/2019 Making a Wireless Charger (4)

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Making a Wireless Charger

I recently made a boost converter (for those unfamiliar with them, they effectively boost the

voltage up to a useable amount) to make a USB Ipod charger using 2 batteries!

"ow that that was done and over, tested tried and true, I decided I wanted to make something

a little more sna##y$

%ideo&http://www.youtube.com/watch?v=MDSYJowwFWM

Uses all '2 volts of (2 in parallel for each cell) lithium batteries$raws under * amps all the time$

I+ve searched around on this website, and noticed that almost all of the instructables on here

with wireless power seem to lack a proper eplanation about how to build one- .r, when they

did build one, they used an inefficient method of doing so!!!

/his transmitter works fantastic, and can run on pretty much any voltage above '2 volts, and

below 20$ It+s also etremely efficient (little power lost) and, it generates almost no

interference! (one wireless power instructable used a s1uare wave in the primary- S1uare

waves have a lot of harmonics, and can cause havoc on computer systems, radios, and other

sensitive electronics)

I+ve come to solve all of these problems$

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Step 1: So you want to make it, right?

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Step 2: The Schematic

/o build it, ust follow the schematic as shown! (If you need help, please, do not hesitate to

message me$

If you+re having trouble identifying the 3.S45/+s pins, look up the part number of the

3.S45/ you+re using, and follow what it says on there!

4or those following it to the book, the I647289+s pin out goes like this, from left to

right-Gate, Drain, an then Source!

3ake sure when you+re making this, the diodes are put in the correct way! on+t mi up your

#eners with your regular ones$

If you mess this up, your 3.S45/s will almost certainly go boom$

:ou could use a S37S laptop cord to power it, which puts out around '; volts! (if you do

decide to go this route, make sure your power supply can handle a good amount of current

draw! 3ine is rated at *!8 amps, and occasionally the .< (overcurrent) detection will trip$)

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I will add a word of warning- If you plan on ust using a =;98, you must "./ eceed '8

volts input, on the transmitter! ue to resonant rise, the capacitor will charge over what the

=;98 is capable of handling! Be careful please$

If you want to put more uice in your transmitter, you must use a buck converter, otherwisethings will be very unhappy on your receiving end!

4or the diodes, the black band on it, or the white band on the U4099=+s indicates the cathode!

/he other end is the anode! (for simpler terms, the cathode is the pointy end of the diode

symbol, where the line goes across it! /he anode is the flat base of the triangle)

3ind you, this is ust for the transmitter$


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Step ": Making the coils

Mathematics of the coil:

D? #!$ infor the 7ft wire

D % &!'()infor the 9ft wire

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Summary equation:

D = 2x*@ (>ength of wire) A ( of turns) Cx@1/(2D) C +

Deriation o- Diameter D e.uation a/oe:

If you know the total length of the wire L= whatever length you want

length of wire in ft 12 = length of wire in in!he" I will !allL

L

! =

num#er of turn"

$lug ! into:

!

r =

2D

plug r into&

? 2r

Conceptua expanation:

"otice that the length of the wire should be from 7 to 9 feet!

/his image& 46EF7SGUE0H6E!35IU3!pg

6eveals that coil is wound threetimes completely and a -ourthtime including the open

ends!

4or sake of convenience let+s turnfeetto in!he"& $ft('2in for every'ft) ?&)in

or if you want Jft instead& (ft('2in for every'ft) ? 10&in

Since the coil is wound three times completely and a fourth time with open ends we canapproimate that the coil is wound 0 times completely!

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http://cdn.instructables.com/F6R/QHPS/GUQ4JRDQ/F6RQHPSGUQ4JRDQ.MEDIUM.jpghttp://cdn.instructables.com/F6R/QHPS/GUQ4JRDQ/F6RQHPSGUQ4JRDQ.MEDIUM.jpg


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"ow you want to take the length o- the wireandiie it /y the num/er o- turns it will

give you the circumference of the single circle about which all 0 turns are wound!

4or =ft having been converted to ;0inwe take ;0inA0 turns? 2'in

circumference (which I will call c) of the circle with the =ft long wire is ? 2'in

c? 2'inan% if you !hoo"e to go with the 9ft long wire in"tea%:

Jft converted to ;0in take '9;inA0 turns? 2=in

c? 2=in

"ow that we have the circumference, we can ac1uire the diameter!

:ou may recall from one of your classes that the circumference of the circle is K2DrK if you

didn+tL now you do! lso recall that I have said above that the letter c is set e1ual to the

circumference ( c? 2'in or c? 2=in ), knowing this we can use the identity of circumference

to find the radius&

>et+s start with using c? 2'in&

'e know thatc? 2'inbut also c? 2Dr! "ow pretty much anyone can see that ' ? ' or 2 ? 2!

>ikewise c? c thu":

2'in% 2Dr

I am hoping you know that the diameter is twice the radius because that+s where I got this

relation&

D ?2r whereD is the diameter of a circle and ris the radius!

ivide 2' by 2D to ac1uire r!

4or the =ft (or ;0in long) wire the radius of the coil is&

r ?2'in? *!*0228*;90J*inrounding r M *!*02

2D

"ow multiply by two to derive the diameter&

D ?2r % D ? 2(*!*02)% D?!;0 M !=in for the 7ft wire&

/herefore the diameter is given by&

4or the Jft (or '9;in long) wire the radius of the coil is&

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r? 2= in? 0!2J=';*0*0;in rounding r M 0!2J=

2D

/herefore the diameter is given by&

D ?2r ?N D ? 2(0!2J=) ?N D? ;!8J0 M ;!8J0in for the 9ft wire

Step ): Making the receier

/he receiving end is less comple! 3ake sure you use the same capacitor value, as well as

following the USB pinout as I have written in the schematic!

:ou can try and eperiment with different turns ratio+s of the coils and see what kind of

performances you get$ /his has to do with resonance, and stepLup A stepLdown ratios!

/ry adding more voltage, and see if you get more distance- another way of possibly

increasing distance is to increase the resonant fre1uency a bit! Increasing the fre1uencyshould give you more distance, with additional current draw!

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/o increase the fre1uency, ust lower the capacitor values! 7ersonally, the lowest I+d go would

be around ' u4! 3ake sure when you lower the cap value, you do it for both the receiving,

and the transmitting ends$

lso, remember, the idea does not have to apply only to USB! I+ve noticed that due to

resonant rise, the filter capacitor charges to the peak of the output sine wave!!!!

t '2 volts into the transmitter, I was getting around 20 volts at the receiver end$ (this isn+t

the effective voltage however- once you put a load on it, it drops a bit) t '8 volts in, I was

getting *8 volts on the receiver$ (wow, that+s 1uite a bit of a ump, huhO)

/his means that you should be able to power other things as well! Use whatever your mind

comes to$

Step ': Thoughts, an 3planation

/he P%S driver is used for a lot of things due to it+s simplicity! :our laptop might be using

the same oscillator format to run its backlights$

Fowever, in this case, the reason it works is because the P%S driver begins by oscillating at

around 89 L 9 kh#! Qe can+t hear it since it+s above our hearing range!

6esonance can be thought of like a 7endulum! 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, ust

instead of speed and height, it+s voltage and current$ :ou can observe it pretty easily with acup of water! If you shake it ust the right way back and forth the water will spill right out of

the cup, due to resonance!

ue to this magic called resonance, the voltage swings in the tank (between the * R * coil and

the 2 u4 capacitor) are much higher than what the input voltage is! 6esonance helps with

transmission distance, and also, as a result of how the 3.S45/S turn on, they+re in what+s

called Pero %oltage Switching, where they turn on and off when the voltage across them is

#ero! (meaning, they generate littleAno heat due to switching losses)! Fowever, due to onLstate

resistance, they still make a little bit of heat!

":Q:, going away from the complicated bits of it, the reason it can transmit power is

caused by magnetism! s 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$) and thus, power is transmitted through air$ /he same basic concept is behind radio

waves- though, amplifiers are needed to get the audio out of the air, and the fre1uency is

much higher$

I made all of the pictures shown in, though, the transmitter picture is a modified version of

the famous 3a##illi flyback driver! (a great, versatile circuit!!! Used for so much, thanks%ladmiro 3a##illi for this$)

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nd, one more thing- In another instructable, once I get some protoboard, I+ll eplain how to

make a buck converter! It+s relatively easy, and re1uires ust a few parts!

nd as a safety note- I+m not responsible for any KoopsiesK you make if you decide to

construct this circuit! :ou "55 to make sure everything is connected properly$

If I do somehow end up winning the 5pilog contest, I would use the laser etcher to first and

foremost, make 7

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Making a Wireless Charger (4)