Re: [CAD_CAM_EDM_DRO] Re: Brushless motors from models and such

Hi Dave,

The standard RC signal is a variable width 4.5-6V (depending on battery
voltage) pulse. The pulses are repeated at 20ms intervals. For servos a
pulse width of 1.5ms = centre, 1ms is fully one way and 2ms is fully the
other way. No pulses means a loss of signal.

For motor control it gets slightly more complicated. Most controllers
have reverse and/or braking. In most cases stationary will be about
1.3ms. 1ms will be full reverse/full braking and 2ms full forwards. All
brushless controllers are programmable so you can set the exact centre
and full reverse/full forward pulse widths. Mach2 can already output a
PWM signal. Maybe if you talk nicely to Art he will add the option to
output RC compatible PWM signals.

Les

turbulatordude wrote:

>Thanks Hugh,
>
>It application would be for a high speed spindle.
>
>seems the current unit of choice is a dremel or similar.
>
>there is a desire to get away from brushed motors for the maintenance
>problem, even if the brushless is less powerful.
>
>I am still not sure about the ESC (electronic speed control) it seems
>that there is a radio receiver in the model and that will output
>something to the (throttle) motor.
>
>For servo's like flaps or alerions or even steering, the servo is a
>motor with gear box that moves about 90 degrees. it receives a steady
>1,500 hz signal to remain at center, or 1,000 hz to move fully one
>way, or 2,000 hz to move fully the other way, or anything inbetween.
>
>What I have not been able to find is what siganl would be needed for
>the throttle.
>
>I do understand the motor needs 7 to 12 volts for POWER, but the
>SIGNAL is something different.
>
>the 15-20mS instruction time makes sense, with a 1-2mS command,
>possibly 20mS for full speed ? I would expect a 'not zero' signal to
>indicate zero speed.
>
>industrially, we use 4-20mA and have 4 to show we are connected, but
>have a zero value. a real zero means the wire is cut or there is no
>power.
>
>>From the looks of things, the motor run in the $80 range and a 20 amp
>or more ESC runs close to $100.00
>
>It sounds a little pricey for a 35,000 RPM motor, but it appears there
>are not a lot of options for high speed motors.
>
>Dave
>
>
>
>Dave
>
>
>