Self accelerating reed switch magnet spinner.

[conradelektro]

Same circuit as in my last post above, but I am now using identical coils for driving and triggering, no cores. This has the advantage that the magnet is not attracted to the coil unless there is current in the coil.

The power draw ist about the same, round 10 mW (6 Volt at 1.7 mA) at about 3000 rpm. At around 4000 rpm ( 7 Volt, 2 mA, 14 mW) the axis jumps out of the magnet bearings because it is not compeltely true.

The coils have 1600 Ohm DC resistance. It looks like the main power consumption is by the LM311 itself.

Will try the littel core less coils with the vertical model. These coils are taken out of 24V relays.

Greetings, Conrad

[TinselKoala]

Looking good!

Maybe larger diameter ring magnets on the shaft would aid stability at high speeds. My maglev HV esmotor gets to over 5000 rpm and is still stable, and probably isn't as well-balanced as your setup is; it has larger diameter ring magnets on the shaft. But it is also driven by the electrostatic field from the charge deposited on the rotor, which is essentially a constant DC value, not a pulsation like your drive coil produces. That might also have something to do with the stability.

I think the vertical hanging design could be made to be a "full-floater" with the use of an op-amp based electromagnet levitation system at the top. You could use either a ratiometric Hall sensor or an LED-phototransistor or LED-photoresistor pair to sense the vertical position and have the op-amp drive the levitation coil's power mosfet. Or an Arduino can provide even more control, as in my vertical levitation system. Unfortunately I don't have any suitable magnets to make a driven rotation system with my vertical levitator.

[conradelektro]

The biggest hurdl is the interaction of the spinning diametrically magnetised ring mangnet (in the middle of the axis) with the base magnets on both ends of the axis. This causes a slow down of the spin and a wobble of the axis. In addition, the middle magnet is distorting the magnetic field of the magnets on the ends of the axis. This is a more static event (because the three magnets on the axis do not move relative to each other), but still, it has a negative influence on the stabilty of the spin (like a rattle).

I also built a bigger model with a 5 mm axis and bigger magnets, and even a 250 mm Long axis does not solve the problem. One probably needs a 500 mm long axis.

Over all, every thing on an axis suspended on both ends with magnets should be non magnetic (to avoid slow down and wobble) which is a contradiction to a "ring magnet spinner".

The model turns, but not as frictionless as one would hope. Most of the 10 mW (which I need for a 3000 rpm spin) are lost on that.

May be the vertical model, which is almost finished (holders for the 1600 Ohm coils are in the making), behaves better.

Greetings, Conrad

[synchro1]

@Conradelektro,

                       Here's an "Electromagnetically levitated pulse motor rotor" from Lidmotor:

http://www.youtube.com/watch?v=jJtzxST5f8A


                       Here's a link to the "Quick and dirty" circuit of Adambus 77:


https://www.youtube.com/watch?v=xKx7Wr9fCfc

[conradelektro]

@Conradelektro,

                       Here's an "Electromagnetically levitated pulse motor rotor" from Lidmotor:

http://www.youtube.com/watch?v=jJtzxST5f8A

Thank you for pointing me to this video of Lidmotor. It probably is exactly what TinselKoala meant with his levitation suggestion.

Greetings, Conrad