Wind generator for a bicycle from a computer fan

I travel by bicycle very often. And I often have problems charging my cell phone, since it’s difficult to find sockets when traveling. I once saw that they were selling small wind generators for bicycles that generate energy from the air flow while riding. This device costs more than $100, which is not particularly cheap. Then I decided to make my own generator from an old mobile phone and a computer fan.
A computer cooler can be used as a generator with some modification.

Will need

Cooler, better 120 mm.
Battery from an old Nokia mobile phone (or another).
5 diodes, better than Schottky, but regular ones will do.
Transistor BC547.
Ferrite ring.
A piece of circuit board.
Switch.
Boost converter with USB output - .

Making a wind generator from a cooler

Let's disassemble the fan. Peel off the label from the back side and remove the retaining ring with tweezers. We take out the impeller.

In the cooler there are 3 outputs from the windings. Let's solder the wires to them. Let's install the impeller in its place.

Then, using multimeterLet's test which two wires produce the most electricity. Then we cut off the extra third wire with wire cutters.

We assemble a rectifier bridge from 4 diodes to rectify the alternating voltage coming from the cooler to direct voltage.

And we connect it to the output of our wind generator.

At average wind speed, the generator produces about 4 Volts at a load current of 60 mA. This may already be enough to charge the battery. But in order to make the most of even the smallest voltage, I decided to assemble a converter that starts working even at 0.7 V.

How to assemble it and what the meaning of the windings is, see here - https://home.washerhouse.com/en/357-vyzhimaem_poslednie_soki_iz_batarejki.html
We assemble everything on a small piece of the board.

According to the diagram, instead of a battery we connect the cooler through a rectifier, and instead LED We connect through a diode to the battery from an old mobile phone.

Next, to charge your cell phone from a 3.7 V battery, you need to connect a boost converter with a USB output to it. The connection must be made through a switch so that the converter does not consume excess energy.

The final assembly looks like this.

How does it all work?

If anyone does not understand how this device works, then I will explain. The wind generator generates alternating voltage and supplies it through a rectifier to a boost converter, which is assembled on a ferrite ring. The voltage from the converter is supplied to the cell phone battery, which begins to charge while cycling. The charging and protection controller is installed inside the battery and there is no need to install an additional one.
Once you've ridden the bike, plug in your cell phone via USB and click a button that connects the 5V converter to the battery from your old cell phone.And all the charge will flow from one battery to the other battery of your phone.
I hope everything is clear now.