Voltage from rotation

[Arouse1973]

I don't know quite enough details to determine if and how the cross section area of the coil will affect the output...
Of course, you could try making a couple of sample coils to find out:
Take the plastic casing from a Pen and wrap the wire around that as an example, then try the same thing with the casing from a marker or highlighter.
Cheap components. Will cost you wire, and maybe a few cents for the pen/marker.
Here's where it gets tricky though... the same number of turns in a smaller coil will have a different inductance and length of wire than the larger diameter... again, I'm not quite familiar enough to determine exactly how this will affect performance. I know about enough to know that more turns will provide a higher voltage output, and that the coils should be wired in parallel if you were to use the arrangement in the second image on post #27.

Perhaps someone has a formula or some example math to help determine the characteristics of the coils and how they will generate electricity.

Its all about number of turns and surface area.
Adam

 

[Arouse1973]

Do you say that this arrangement:

would work better than this one ?
[img=http://s11.postimg.org/vdb4dq5lr/image.jpg]

Looking at your drawing again. You need to make sure the coil passes through the magnetic flux of the magnet. It difficult to explain. I may have to do a drawing.
Adam

 

[wdariusw]

Today's project - coil winder

Now i can wind all coils with identical number of turns, coils are nicer, and sine wave on oscilloscope is with less noise. Coil winded with new winding method is in the right:


There are 600 rotations using 0.2mm cooper wire. New coil gives about 30mV bigger voltage at same magnet rotation speed.

 

[Arouse1973]

Have you turned the coils and magnets yet?
Adam

 

[wdariusw]

Have you turned the coils and magnets yet?
Adam

No. I have problem's with my knee..doctor will operate my in these days, very difficult to work, even sit... :/ please make simple drawing how you suggest me to turn magnets and coils, thanks !

 

[Arouse1973]

Here is what I mean. The brown rectangles are the coils and the grey ones are the magnets behind the coils.
Adam

 

[wdariusw]

Will try it this week. Now I can't work with it day or two... If it needed to detect rotation direction, what sensor fits here? Hall sensor i think here can't help..

 

[wdariusw]

But if i need that the signal would transmitted when there are proper direction? If cyclist pedals backwards , then no signal should be transmitted.

 

[Arouse1973]

You could add some circuitry to do this like a diode.
Adam

 

[wdariusw]

What king of diode? I think i need something attach on the magnetic circle, and with something watch it.

 

[Arouse1973]

Can you show me the electrical circuit you think will be the final design?
Adam

 

[wdariusw]

Will draw it maybe tommorow. Now i'm in hospital..:-/

 

[wdariusw]

Here is what I mean. The brown rectangles are the coils and the grey ones are the magnets behind the coils.
Adam

View attachment 18324

Hi. Tried this today,but the voltage is much lower...So it is not right positioning for my design. Today got bigger bigger magnets for another form (post #21 left picture). Winded 2 more coils with 0.2mm wire and 600 rotations. Did full wave bridge rectifier, and got little more than 400mV DC, I think it is not bad ! Will wind more 2-3 coils and will see what I got then .

 

[Arouse1973]

Ok worth a try. Good luck
Adam

 

[wdariusw]

Today all day I spent with research and experimentation. I got this energy harvesting kit http://www.ti.com/lit/ug/sluu654a/sluu654a.pdf . There are written boost converter starts when >=300mV is in the input. When i connected my rectified voltage (400mV) , it drops under 300mV and the board do not work at all. Then i wound it one more coil (now there are 4 coils). Then I found voltage multiplier schematic and did simulations :
After that i soldered everything and got 1.5V on oscilloscope screen. Connected to bq25504 board with supercpacitor insteed battery, and after lot rotations of my test system there was enought energy for LED blink for 1s. It is something! Do not know how to increase power generation at that moment..

 

[Gryd3]

Today all day I spent with research and experimentation. I got this energy harvesting kit http://www.ti.com/lit/ug/sluu654a/sluu654a.pdf . There are written boost converter starts when >=300mV is in the input. When i connected my rectified voltage (400mV) , it drops under 300mV and the board do not work at all. Then i wound it one more coil (now there are 4 coils). Then I found voltage multiplier schematic and did simulations :
After that i soldered everything and got 1.5V on oscilloscope screen. Connected to bq25504 board with supercpacitor insteed battery, and after lot rotations of my test system there was enought energy for LED blink for 1s. It is something! Do not know how to increase power generation at that moment..

Only thought at the moment is much thinner wire, and more turns for your coils.
Glad you are making progress!

 

[wdariusw]

I can buy 0.063mm cooper wire, but my thought here - voltage increases, but current decreases ? Or not ?

 

[Arouse1973]

You need to remember that small magnetics will never produce that much power transfer. Work it out its easy. You need to remember you are on the outside of the coil.
Adam

 

[wdariusw]

But here thinner wire than 0.2mm would help or not?

 

[Arouse1973]

I dont see how thinner wire can help only the fact you can wind more on the bobbin but this reduces the Q. You need to do the math and see what magnets and coils you need. Trial annd error will take a while.
Adam