Re: servo driver on a chip ?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@...> wrote:

>
> Hi all,
>
> A friend is just getting into CNC and wanted me to look for a
> home-brew way to use servo motors.
>
> There are servo drivers on a chip, but the one found is for

postioning

> servo's

This is called an RC-servo. They are generally plastic boxes with an
actuator arm that is driven by a geared DC motor. They are open
loop and do not include position feedback within the control loop.
The units were initially used in RC-remote controlled aircraft, cars
and other models, and are now finding many uses in robotics.

>not step and direction use.
>
> Is there a name for the two different technologies ?
>
> both being servos is confusing.

The step and direction servos are closed loop and use an optical
encoder to control position.

Inexpensive assembled, closed loop S&D servo drivers include:

DeskCNC SV-500 ($65) http://www.imsrv.com/deskcnc
Gecko G320 ($114) http://www.geckodrive.com
Rutex R2010 ($148) http://www.rutex.com
CNCTeknix Tekdrive ($225 approx) http://www.cncteknix.com

Another similar device that may be of interest is the Pixie. It is
a step and direction closed loop servo with analog output that can
be used with many of the analog servos that are used on commercial
CNC machines. Pixie P-100 ($69) http://www.skyko.com

Fred smith - IMService
http://www.cadcamcadcam.com/hobby