Re: [CAD_CAM_EDM_DRO] Differences between AC & DC brushless

On Thursday 25 March 2004 12:44 pm, Jon Elson wrote:

> To be strictly correct, the only motor that can be called DC brushless are
> the ones on computer fans and the like, where the commutation function is
> built INTO the motor, and it has only two wires coming out.

I've not taken one of these that far apart, but am wondering if they werk the
same way as the direct-drive stuff that started showing up on floppy drives
after the belt-driven stuff went away...

> The other general types are (1) permanent magnet brushless motors, where the
> rotor poles are always in the exact same spot on the rotor, hence the
> encoder provides commutation info to the drive.

Speaking of fans they sure seem to have permanent magnets in there someplace
as on the CPU fan of the test board that's sitting here. I'm not sure I see
the distinction you're trying to make here.