Anyone use a stepper motor?

[No_6]

I was thinking of using a couple of these for the bussard fans on my next E build, but I've never used them before. Can you regulate the current so that it will rotate slower than 50 RPMs?

[macfrank]

I was thinking of using a couple of these for the bussard fans on my next E build, but I've never used them before. Can you regulate the current so that it will rotate slower than 50 RPMs?

A stepper is probably not a good motor for this application. You'll have some difficulty finding one small enough to fit in a nacelle. The drive circuit (depending on the stepper windings) will need at least 4 high current drivers, plus extra circuitry to generate the phases required for the motor to step.

You would be better off with a small DC motor (like the ones from a pager vibrator) and a 555 timer. If you play with the pulse width and frequency, you can get a smooth and relatively low power motion.

Another option would be a servo motor modified to rotate 360 degrees. Getting one small enough to fit in a nacelle may be expensive. You would still have to drive it with a 555 or some other pulse generator.

[Umi_Ryuzuki]

Most servo motors are going to be blocky, and difficult to fit in a nacell.
It will also be noisy,... grindey... They are really not quiet at all.

This is the rotaton you can expect on about 3.4 volts...
http://video.google.com/videoplay?docid ... adar&hl=en

It is almost annoyingly noisy...

I later switched out to use a gear motor from Gizmozone.
Much smaller, but not any less quiet...

Rpm down as low as 25 - 50...
http://www.gizmoszone.com/shopping/stor ... r;ppinc=1a