Self accelerating reed switch magnet spinner.

[Magluvin]

I had to take it apart to reglue a magnet, so here's the underside view of the rotor, showing the assortment of magnets. It's all I had available when I made the original Bedini SMG that I am recycling!

Hey T

What are the black parts with the silverish magnets in the lid? 

Mags

[TinselKoala]

@TK,


      This circuit looks like it may spring to life by lightning strike. Watch it now! Maybe your dog can help lick clean what's left of the peanut butter from inside the lid.

The white-out is getting so thick on the page I am afraid to try to close the notebook!

[TinselKoala]

Hey T

What are the black parts with the silverish magnets in the lid? 

Mags

There are four black ceramic magnets: two round ones and two "bars" polled on the long faces. Then I stuck a little NdBFe on top of each ceramic magnet.

This was the only way I could get the old Bedini SGM to work, with the magnets I had on hand when I built it. I do have another set of matching magnets now that I could put in there... and someone gave me a set of Steorn superstrong concentric ring magnets for bearings .... but the pivot bearing is already better than a ball bearing would be.... so work continues.

[Magluvin]

There are four black ceramic magnets: two round ones and two "bars" polled on the long faces. Then I stuck a little NdBFe on top of each ceramic magnet.

This was the only way I could get the old Bedini SGM to work, with the magnets I had on hand when I built it. I do have another set of matching magnets now that I could put in there... and someone gave me a set of Steorn superstrong concentric ring magnets for bearings .... but the pivot bearing is already better than a ball bearing would be.... so work continues.

Seems to work fine mismatched. Just wondered.  All of this could be done much the same with an arduino. Have you thought about it?  on/off timing, timing adjustment, led strobing, etc. Im working on an arduino setup using a joystick for manual fine and course tuning. Makes adjustments on the fly while watching meters n scopes. The duino will beep high n low for course and fine digit changes so without looking I know it made the change. Fun stuff.

Mags

[TinselKoala]

Well, this is exciting! I've had my first component failure! Any guesses as to which one?

As I switched the "PTO Mode" switch the thing died. The motor stopped running, the coil was constantly energized, mosfet Drain signal at zero. Blown mosfet?

Nope... the 10 nF poly film cap between Drain and Source failed shorted. I used a Sprague 80 volt unit.... surprised it lasted this long. Replaced with a 400 V unit from an old TV chassis.... all is once again copacetic, motor runs great once again! Mosfet is fine.


@Mags:
Yep, I think the hot setup would be to use the Arduino to provide the reference voltage for the comparator driver! The rest of the Arduino could monitor stuff, and you could even put in a feedback loop to do the small changes in duty cycle and timing required for acceleration/load rather than just free running max RPM.

But seriously... this driver, including the power mosfet, has less than ten dollars worth of parts!
TL082,    0.71 (DigiKey)
4017,      0.52      ''
555,        0.43      ''
IRFP360, 3.79      ''
NE-2E      0.32 (Mouser)
10-turn trimpot 2.49 (Mouser)
some scavenged parts from old TVs (cap, relay coil)  free