Re: [CAD_CAM_EDM_DRO] Re: stepper vs. servo - H Bridge question

Albee you're missing a very significant point - a Gecko or a Rutex or
any well engineered drive for a servo is not just an H bridge.
Simplistically, there's a feedback loop which tracks encoder counts and
direction, there's PID gain/damping settings to optimise drive
performance and minimise tracking errors under different load conditions
etc etc. Look at the white papers on the Gecko website and read the
FAQ's. (Your question is "frequently asked"...) Look at some of the
block diagrams at vendor's sites you start to see the added complexity
to make the thing work reliably. If you want to learn about motor
drives then there are definitely low power roll your own options
available from various sources but if you want to play with CNC and get
reliable performance and accuracy, then spend the bucks and buy that
(and a few other critical) components.

If your National motor has one red and one black wire coming out of it,
you're half way there. Try connecting a 12V battery to it and see what
happens. If you can measure the RPM's at 12V, you will have a good idea
what voltage you will need to achieve your max rpm's for your system,
taking belt reductions and leadscrew pitch into account. You also need
an encoder on the back, which will have a number of wires (or a
connector) coming out of it. Read the Gecko white papers to better
understand how the encoder works and feeds into the drive. The Rutex
website also has very useful info on setup. "Generally", if the motor
is less than or equal to 4" in diameter and less than 6" in length, it
will most likely be very happy with a Gecko or a Rutex drive.

Cheers Peter

Albee Tang wrote:

>Hi guys,
>
>Talking about Gecko G320 servo driver. Are they fit for any type of DC Servo
>motor? I have a National Servo motor but I could not find the Electrical
>specification.
>
>By the way, instead of buying Gecko G320, can we just build one using some
>Power MOSFET construct it in H-Bridge? Wouldn't that be cheaper than buying
>a Gecko driver?
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