DIY Wireless Charger

47,630

35

33

About: Electronics hobbyist

In this Instructable, you will be going to know how to build your own wireless charger for any device.

HOW ?

Wireless power techniques mainly fall into two categories, non-radiative and radiative. In near field or non-radiative techniques, power is transferred by magnetic fields using inductive coupling between coils of wire, or by electric fields using capacitive coupling between metal electrodes. Inductive coupling is the most widely used wireless technology; its applications include charging handheld devices like phones and electric toothbrushes, RFID tags, and chargers for implantable medical devices like artificial cardiac pacemakers, or electric vehicles.

What is Inductive Coupling :

In inductive coupling (electromagnetic inductionor inductive power transfer, IPT), power is transferred between coils of wire by a magnetic field. The transmitter and receiver coils together form a transformer(see diagram). An alternating current (AC) through the transmitter coil (L1) creates an oscillating magnetic field(B) by Ampere's law. The magnetic field passes through the receiving coil (L2), where it induces an alternating EMF (voltage) by Faraday's law of induction, which creates an alternating current in the receiver.The induced alternating current may either drive the load directly, or be rectified to direct current (DC) by a rectifier in the receiver, which drives the load.

Resonant inductive coupling

According to the coupled mode theory proposed by Marin Soljačić at MIT, resonant inductive coupling(electrodynamic coupling,[12] strongly coupled magnetic resonance) is a form of inductive coupling in which power is transferred by magnetic fields (B, green) between two resonant circuits (tuned circuits), one in the transmitter and one in the receiver (see diagram, right). Each resonant circuit consists of a coil of wire connected to a capacitor, or a self-resonant coil or other resonator with internal capacitance. The two are tuned to resonate at the same resonant frequency. The resonance between the coils can greatly increase coupling and power transfer.

IF you want to know more about the topic follow this link :

https://en.wikipedia.org/wiki/Wireless_power_trans...

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: WHAT YOU WILL NEED!!!!!!

You will need following components to begin with :

Dot PCB Board (x1)

wire 1 mm thick (7 m)

IC 7805(x1)

IRFZ44N MOSFET (x4)

IR2110 MOSFET driver IC (x2)

555 timer IC (x1)

CD4049 IC (X1)

10K trim pot [103] (x1)

10k resistor (x4)

10 OHM resistor (x4)

0.1uF capacitor [104] (x5)

10nf capacitor [103] (x1)

2.2nF capacitor [222] (x1)

10uF capacitor [electrolytic] (x3)

47uF capacitor [electrolytic] (x1)

47nF capacitor [polyester] (x2)

Screw Terminals

IN5819 schotky diode (x6)

Mini USB connector [male] (x1)

DC - DC 5v Buck converter

So lets start with the build.

Step 2: Winding the COILS!!?

winding a perfect spiral coil is a bit tricky.

Here is my way of winding the coil. First of all cut a small circle of diameter 1 cm with a cardboard, glue it to a piece of cardboard and make a hole in the center.

NOW, take the wire of 1 mm thickness and pass it through the hole made in the center (this is extra bit of wire for electrical connections).

Apply a lot of glue on the surface and start winding by going around the circle (glue helps in holding the winding in place). Keep on winding until number of turns becomes 30. Make 2 such types of identical coils.

Step 3: Make a Measure:

If you have a LCR meter you can skip this step. If you don't have a LCR meter , the build an inductance meter from an Arduino Uno and an op-amp (LM339). I have taken this circuit from the following website, you can find more information about this inductance meter in the website itself.( the code is also available in the website itself)

http://www.electronoobs.com/eng_arduino_tut10_3.ph...


Now, measure the inductance of the coils with this meter and if you have all the conditions same as mine that is

1.0 mm thick wire, inner diameter of the coil = 1.0 cm, number of turns = 30.

you should get the inductance of the coil around 21.56 uH 26.08 uH because of unknown error.

Now after getting the inductance, you have to calculate the Resonant frequency of the LC circuit.

Given By The Formula :

F = 1 / (2*pi*sq-rt(LC))

you can use this online calculator calculate the frequency of resonance.

http://www.deephaven.co.uk/lc.html

In my case,

L = 26.08 uH and C = 47 nF

which gives the resonant frequency of F = 143.75 Khz.

now, we have to build the oscillator circuit, whose oscillation is of the frequency 143.75 Khz.

Step 4: The Oscillator Circuit...

There are lots of way of making an oscillator circuit . In this circuit we will use a 555 timer IC to produce a signal of 143.75 Khz but its not enough to drive the LC circuit(transmitter coil with capacitor in series). so we have to build a H bridge mosfet driver circuit to drive the LC circuit.

http://microcontrollerslab.com/how-to-make-h-bridg...


With reference to the circuit on the above website and some minor changes I have made a circuit to drive the LC circuit.

Just follow the circuit that I have attached here.

WORKING:

The 555 timer IC in Astable Multivibrator with 50% duty cycle produces the required oscillating signal which is fed to the IR2110 IC.

The full H bridge Mosfet driver circuit to will output square wave when the inputs A=D and B=C and B(C) is Inverted state of A(D). So an Inverter IC (4049) is used to achieve this.

This oscillating Voltage creates a sinusoidal current through the transmitter coil which induces magnetic field around it.

when the receiver coil in parallel with a capacitor, whose resonant frequency as same as that of the transmitter coil is placed in its magnetic field current is induced.

This induced current is converted to dc using bridge rectifier and regulated to 5 V DC to charge the mobile using a buck converter.

Those who want to make the printed version of this project, I have attached the Eagle board files also, check it out.

Step 5: #Final Measure:

Now, after building all the circuits according to the schematic check everything and also measure everything.

again if you have any device to measure frequency then its okay, if not just upload the following codeto Arduino Uno.

web address : https://forum.arduino.cc/index.php?topic=324796.0...


Measure the frequency at 3rd pin of the 555 timer IC.

while measuring the frequency adjust the 10K trim pot to get the required frequency (i.e, 143.75 Khz).

now take a multi meter measure the following parameters:

Input Voltage[ Vin ](i.e, check whether it is exactly 12 V or not).

Input Current[ Iin](i.e, current to the circuit from 12 v power supply).

Output Voltage[ Vout ](i.e, check whether it is exactly 5 V or not).

Output Current[ Iout ] (i.e, current to the mobile from buck converter).

Calculations :

Pin = Vin * Iin

Pout = Vout * Iout

Efficiency(n) = Pout / Pin

My readings : Vin = 11.8 V ; Iin = 310 mA ; Vout = 5.1 V ; Vin = 290 mA

which gives efficiency of 40.4%

Step 6: #The Enclosure.

I have recycled an old mobile box as the enclosure as you can see in the image.

once you have done, you can charge mobile or any device that requires 5 volts, the charging current is 300 mA.

(which is bit slow for mobiles). The output power can be increase further but the efficiency will decrease.

As you can see I have connected a mini USB connector at the output of the buck converter. This can be connected to any device and can be charged wirelessly.

Step 7: Moment of Truth!!!!

WHY SO INEFFICIENT :

As you can notice the efficiency of this is very low, but why? It is due to poor air coupling, skin effect and error in inductance of the hand winded coil and the frequency of the oscillator circuit itself is not stable.

so how do we overcome these problems??? well we can utilize special type of wire called LITZ WIRE to over come skin effect. The effect by which the current passes only through a certain depth of the conductor at high frequency is known as skin effect. We can also use Ferrite base to increase inductance and increase the coupling of two coils effectively. Of course there are many coils in online shops with the above requirements which can be used to increase the efficiency of the wireless charger.

If you want to build this for demonstration purposes the above coils are enough. But, If you want to use this for any daily purposes I suggest you to buy one online.

If you like this project and found it some what informative and helpfull, the please vote for my project.

Thank you.

Wireless Contest

Participated in the
Wireless Contest

Share

    Recommendations

    • Indoor Lighting Contest

      Indoor Lighting Contest
    • Make It Fly Challenge

      Make It Fly Challenge
    • Growing Beyond Earth Maker Contest

      Growing Beyond Earth Maker Contest

    33 Discussions

    0
    None
    zoky

    8 weeks ago

    I have in my area so call smart desk. With USB connectors but I cannot use it because most time is inacapacity by vandalism. But smart desk have both wireless crarging standard so actually I just need wireless receiver. Any way I found many information, so if I made them work , charge on wireless spot on smart desk I will be send information how

    0
    None
    Xx Robin_the_

    Question 6 months ago

    Whats LSP 1 and 2, and is it possible to make the circuit without it?

    3 answers
    0
    None
    Xx Robin_the_Maker BR

    Reply 3 months ago

    thanks, and i have one more question, if i put a phone with wireless charging on the pad of this wireless charger will it charge the phone ?

    0
    None
    Maker BRXx Robin_the_

    Reply 3 months ago

    I don't think so, because ur phone's wireless charger will have different resonant frequency and also it needs some kind of information from the charger to pair it.

    0
    None
    NiAdS

    4 months ago on Step 7

    please i need some information

    0
    None
    CarolinaA39

    5 months ago

    Hi! I am trying to build this circuit but I am having trouble with the output signal from my transmitter. From my two drivers I am getting the correct square waves but when I connect it all in series with the capcitor and the coil, the receiver coil is getting a critically damped sine wave. Do you know what I am doing wrong?

    8 replies
    0
    None
    Maker BRCarolinaA39

    Reply 5 months ago

    From what type of source are you powering this circuit

    0
    None
    NiAdSMaker BR

    Reply 4 months ago

    hello i have question to ask

    0
    None
    CarolinaA39CarolinaA39

    Reply 4 months ago

    I am using a the DC powersupply with 12V, 1 A output, trying to simulate the 12V-1A adaptor that I am planning to use in the circuit later on.

    0
    None
    Maker BRCarolinaA39

    Reply 4 months ago

    Can you try increasing the current limit upto 2A and see if the problem still exists.

    0
    None
    CarolinaA39Maker BR

    Reply 4 months ago

    Will do. What adapter did you use to connect the transmitter to the wall?was it a 12V-1A?

    0
    None
    Maker BRCarolinaA39

    Reply 5 months ago

    Could you be more specific. Are you sure that it can provide enough current to the circuit.

    0
    None
    ChaseJ12

    5 months ago

    Hi! Excellent circuit. I've been using it for a while but out of no where the signal from my receiver coil is damping when putting it in series to the transmitter coil. I checked the output signals from both of my drivers and they look fine. Do you know why this might be happening? Thank you so much

    0
    None
    rhydianp

    Question 10 months ago on Step 1

    how much will all the components cost

    0
    None
    MadhuM35

    10 months ago on Step 1

    Where we get these all things sir can you please tell me am live in Hyderabad

    1 reply
    0
    None
    Maker BRMadhuM35

    Reply 10 months ago

    You can get all the components in local store, I got it in the local electronics components supplier store and I live in Bengaluru.

    0
    None
    julian_hiorns

    1 year ago

    I'm replying as a "new" comment because the thread Reply button is not working at the moment. I've looked at the circuit (from microcontrollerslab.com) you used as your starting point for this design and it has all gate bias resistors connected to their respective FET source pins. In my view, this is correct. I understand that your build has worked correctly: my build burnt out two transistors the first time I switched it on. After moving the bias resistors to the source side of the transistors, no further problems occurred. A possible reason is this. When the circuit is first powered, the drive pins from the IR2110 may come up in an indeterminate state. If the gates of either or both of Q1 and Q3 are connected to their respective drains, this means they may be set to "on". If Q2 or Q4 are also on, then you have an effective short across the rail. It may only be for a few tens of microseconds, but if Ciss is around 2-3nF and it's charging through 10K, then that is more than enough time for a catastrophic failure.