Simple generator

[broli]

kEhYo77, that's really cool are you planning on building one too?

gyulasun, thanks for the suggestions. Currenlty I have settled with a silicon steel transformer, to be more precise this one:

http://www.conrad.be/ce/nl/product/514276/Universele-nettransformator----15-V----15-A----225-VA----elma-TT/SHOP_AREA_17430?

The holes make it easier to mount and allign in some sort of fixture. When I have the time I'll try to design a stator to hold 8-10 of these transformers and 3d print it . The real challenge is building the rotor to be sturdy to avoid having the magnets bend the whole rotor and stick to the transformer when the airgap is small. Any collaboration is welcome .

[kEhYo77]

I have got enough transformers and a prime mover DC motor with the shaft extending from both ends so maybe I'll build one
Two rotors might be made from small weight lifting iron discs, They would serve as a flywheel and as magnetic flux linkage for those not used sides of the magnets.
I don't know when it is going to happen but the urge is there 

[gyulasun]

Hi Broli,

I had a look at the transformer you linked to at Conrad, it seems also okay to me (like the ferrite current transformers I proposed), the difference being in size and price.  Regarding the coils on the trafos, the only requirement may be to have as small copper DC resistance as possible, this calls for having coils of thick wire. 

I agree that there is a mechanical challenge in building robust rotor discs which are able to withstand any bending force coming from attraction. What kEhYo77 suggested (weight lifting iron discs) sounds good to me because those types of discs can be rigid enough indeed. When making such discs, radial ribs on their outside could enhance their rigidness. Perhaps making the discs with a bit higher OD than the stator would have with the transformers, you could place a few supports (distance keepers) between the discs at symmetrically opposite places.
First I thought that eddy currents in the iron discs could cause an unwanted loss but then I figured that the actual flux change via the iron discs must be small by default because the transformer cores insure a continuous quasi-closed magnetic circuit between the discs and their magnets all the way within the full circle. So the magnetic properties of iron material for the discs are not demanding, it seems.   

Gyula

[broli]

The transformers arrived today. They have very flat sides which is a good thing when wanting the airgap to be as small as possible. They are rated at primary:230V, secondary:15V. This has the advantage to quickly swap between winding ratio and study the difference. In the pictures below you can see the orientation variants I'm thinking of.

Now for the more difficult job, designing the bracket to hold these in place. My new DLP 3d printer will arrive soon, so that will also help.

[gotoluc]

Thanks for your update broli

I'm very interested in your idea and still trying to understand why Lenz won't come into play in your generator design.

Looking forward to your tests and wishing you success.

Luc