Simple generator

[broli]

You reasoning is incorrect though, the coil does not cause a high reluctance path. If you study basic "magnetic equivalent circuits" you will know the coil acts like a voltage source and not a resistance (to the flux):

http://www.tutorialsarea.com/EEE/Electrical%20Machines-I/1/Analysis%20of%20Magnetic%20Circuits.html

This is also shown in FEMM, the total flux is the sum of the flux that the coil would generate as if there was no magnet PLUS the flux due to the magnet as if the coil was not energized. It's simple vector math in this case. So it doesn't matter if current is flowing or not (if stay away from saturation that is).

I ordered some capacitors today to start testing out LC tank operation of this motor/generator. However I first need to build a proper frame to achieve high RPM's. Would be glad to see others building this as well as I know there are much more clever people in the community that can do and see things I don't.

[lumen]

You reasoning is incorrect though, the coil does not cause a high reluctance path. If you study basic "magnetic equivalent circuits" you will know the coil acts like a voltage source and not a resistance (to the flux):

If it were not for the copper ring on a shaded pole motor delaying (resisting the flow of) flux, the motor would not start.
That small single loop of copper will delay the passage of flux because it induces a current in the ring and it generates a flux in the opposing direction. (Lorentz force)

In a static condition the flux will balance, but dynamically the coil with a load will oppose change.

I'm just saying it's my view of where a problem with low current will arise. Low current is not always the enemy, as little for free is better.

[gyulasun]

Hi Broli,

Okay on your ball bearing type, it has surely got good quality and I understand that it is the attract force which makes the rotor move bitty. This can be solved by say a double rotor setup where two attract forces act on the toroidal core so they may cancel each other.

I'm curious to see what will happen when the LC tank hits its frequency.

Well, if you tune out the 80mH coil inductance, say you use a series capacitor, then there remains the DC resistance of the coil to set the load current together with the load resistance you would use. To achieve power match (=maximize power transfer), you would need to use an equal value load resistance to the coil's DC resistance. This way half of the induced voltage would appear across the load resistance at the chosen rpm you tuned out the 80mH with a series capacitor.

By the way, you mention 1.5 Ohm for coil DC resistance but in your video tests the voltage and current values shown by your power supply V-I displays give about 1.2 Ohm calculated Dc resistance that includes the connecting wires to the coil too. Of course this is not a big difference vs 1.5 Ohm but may count when the induced voltage in the coil is only 200 - 300 mVpp. And in the some Amper range the crocodyle clips may introduce further losses.

Some numbers to get the series capacitor values for different rpms:
    60 rpm=    1Hz at 80mH needs  316665uF tuning capacitor
  600 rpm=  10Hz at 80mH needs     3166uF
3600 rpm=  60Hz at 80mH needs         88uF
6000 rpm=100Hz at 80mH needs        31.6uF

You have surely arrived at similar capacitor values and ordered some for some chosen rpm rotor speed.

Thanks,
Gyula

[lumen]

Broli, Thank you for sharing your experiment. I have been thinking about it for several days because it has this sense of design that seems to skirt the Lenz effect but not totally.

I would like to offer an extension to the same design that appears in concept to totally eliminate Lenz and still output large current.
The thread at this time is mainly composed of you and Gyula so if either object to me posting a modified CAD drawing of your device in your thread I will reserve it until I find some time to construct it.
If nothing else it could be food for thought.

[broli]

No problem at all, it's always nice to see ideas sparking off new ideas. That's the power of sharing your work.