Have you ever heard of charging your phone just by walking?

Yes!! is is possible by an short experiment. Here's a little secret on making insoles that can charge USB devices...!!!

## Step 1: Concept Behind the Project

The secret behind this experiment is "Piezoelectric Disk". The piezoelectric disk generate a voltage when deformed (change in shape exaggerated)

## Step 2: Parts/Materials

• Piezoelectric Disk(6*)
• 1N4007 Rectifier Diodes(4*)
• Wires Aluminium
• Old Pare Of Shoes
• 3.7v mobile battery
• Switch
• USB Port
• Voltage Regulator 5v
• USB DC-DC Mini PFM control (0.9-5v) (step up convertor)
• Lithium Battery Charger Board USB 1A 18650
• Electric Tape

## Step 3: Measuring&Cutting PVC Board

Trace your shape of sole on your PVC material and cut it carefully.That cut PVC sheet will act as a base plate where you had earlier made your circuit.
NOTE-choose your base material carefully. i have tried every thing wood, rubber, hardboard etc but according to me plastic is best, but also choose your PVC material very carefully it should not be too thick nor too thin, it should be 2-3mm

## Step 4: Measuring and Cutting Board

Make a triangle in between the base plate such that three piezoelectric disc can be fitted inside,then Make three holes on your base plate in your triangle , of size of inner circle of piezoelectric disc.

## Step 5: Pasting Piezoelectric Disc

Why i have called This whole arrangement "sandwich"?

It is best suitable word i can think for this arrangement. piezoelectric disc will act as a bread and base PVC cutted material act as a binding agent.

## Step 6: Connecting All Disk Together

Solder all disc in parallel to each other .don't connect these in series because we need more current then voltage.And repeat the same thing in other side and connect both positive and negative wires together, so in end we will get only two wires (+)&(-) containing whole current
But here we have a problem....

By our whole arrangement we will get AC(Alternating current) but to charge ant USB devise we need DC(Direct current). So we will attach a Diode bridge to convert AC to DC.

## Step 7: Connecting Diaode Bridge

Diode bridge or full wave rectifier device to convert AC to DC current without changing the amount of current.So solder both wire to diagonal corners of bridge and by other two corner will get our DC current
NOTE- solder wires and make your bridge carefully because we have to be careful about 'forward Biassing'
and 'reverse biasing'

## Step 8: Adding Foam Pusher

We have to add form pusher on our discs, because of our comfort and main reason- because of surface area "Lesser the surface area More the Pressure"

## Step 9: Testing on Voltmeter

Now we have to test our whole arrangement On voltmeter
It should produce

• 10-15v pressing by hand
• 20-25v while walking and
• 25-30v while running

## Step 10:

Pin No Function Name

1 Ground (0V) Ground

2 Ground Input voltage (5V-18V) Input

3 Regulated output; 5V (4.8V-5.2V) Output

The two wires from diode bridge containing DC voltage ,will now be connected to voltage regulator

The first wire should be connected to input pin where as , the another would be connected to ground pin

## Step 11: Making of Power Bank

For making a power bank , firstly connect the positive output point of lithium charger to the positive terminal of battery and further connect that wire to the input (positive) point of step up convertor(5v)

And now vice versa with the negative point.

Note- As you can see i have used mobile battery instead of cylindrical battery (both are same thing of 3.7v)

and I have used double sided board in place of to boards (it is better, it occupies lesser space)

## Step 12: Connecting Power Bank to D.C Generator

The output and ground points of D.C generator would be now connected to the input points of lithium charger.

And taped it well....

## Step 13: Final Setup

Connect the positive points of U.S.B port to the (+) output end of step up convertor and negative end of U.S.B port

would be firstly connected to switch,then further connect the same with the output (-) point of step up convertor......

If you have any queries then send me mail on "grandmaster.rp@gmail.com" write it in comments
<p>Nice application and simple, thanks for sharing. I can see other charging applications.</p>
what's the current output from the piezos??<br>
It's already mentioned in step 9..
<p>thats just voltage u mentioned.</p><p>I wanna know if it will work if we start with a dead battery.(I assume ur battery was already charged)</p>
I'm sorry but your assumption is wrong.. I have used the dead battery only..
No, I have used the dead battery only .. It was not charged earlier .. For dead battery to be charged you have to walk more than a hour..