| > The problem is that the ESC `senses' the position of the motor and
| > adjusts the voltage (or, to be more precise, the polarity and the duty
| > cycle) it sends accordingly. If the motors are not in the same
| > position, then it's not going to be able to send the right voltages to
| > each pole of each motor.
| how does it do that without a "tach" feedback and only three leads?
Well, the old brushless motors have three leads for the motor power,
and a five more for the sensors.
The new brushless motors only have three leads for the motor power,
but the ESC can detect the position of the motor based on the voltages
that the motor leads are putting out.
The old setup had a lot more wires, but it did have one advantage --
it usually wasn't too difficult to adjust the timing of your motor,
just by moving the sensors forward or back. With the new sensorless
ESCs, the timing is generally fixed in the ESC (though some of the
high end ones may let you adjust it.)
(You can also use one of the new ESCs on one of the old brushless
motors -- you just don't plug the sensor wires into anything.)
http://www.ezonemag.com/pages/faq/a412.shtml goes into a little bit of
detail. http://www.rcuniverse.com/forum/m_1558046/tm.htm is a
discussion that goes into a bit more detail.
Brushless prices have come way down recently. Give it a few more
years, and the brushed motor may go the way of the dodo ...
Doug McLaren, firstname.lastname@example.org
Those who live by the sword die by the arrow.
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