On 12/1/2013 10:42 PM, Carl Ijames wrote:

I wanted to try one of these as a cheap alternative to a conventional
brushless dc motor in a mechanism we were prototyping at work, so I grabbed
a couple with controllers off ebay to explore. Then I learned that the
control input needed to be a variable duty cycle digital signal, something
like (from old memory so I'm sure it's a little off) 10 or 15 ms period and
0-5 msec on time for 0-100% of motor speed, sigh. I used a signal generator
to fake it for the initial tests but it would have been a pain to drive it
with our controller if it had worked out (we were set up to output 0-5V for
0-100% motor speed). After getting the parts it was clear that the ESC and
the motor winding could handle some pretty hefty currents to make the hp
they claimed, but there was no way they could dissipate even 10% of the
resultant heat steady state. These were airplane motors and ESC's so they
were engineered to run for 1-2 minutes max, and then have many, many minutes
of cool down time while the battery pack was recharged or swapped out. The
motor bearings were pretty wimpy, too, so I was afraid that putting a pulley
on the motor shaft and having the lateral load from a belt would kill things
pretty quickly, but I never got that far since it was obvious that the
package wasn't what we needed. Hey, it was a fun experiment, anyway :-).
I'll dig one out Monday or Tuesday and see what rpm it's rated for, maybe
you could play with one.

-----
Regards,
Carl Ijames



I don't know anything about your controller, Carl, but pulse width
modulation is really fairly trivial (these days!).

http://www.instructables.com/id/QuickStart-one-transistor-DC-motor-controller/