Re: Gecko 320 VS. 340

Bill,

DUH! My mistake, I seem to have G420 on the brain lately.

The G340 is a G320 with a pulse multiplier board (G901) added.

The G340 is marginally more usefull than an open sun-deck on a 747.
Its main purpose is for those who are stuck with a high resolution
encoder and a wimpy step pulse source. It will turn a fine 1,000 line
encoder into a 100 line one, so why not start with a 100 line encoder
to begin with and use the less expensive G320?

A secondary purpose is to minimize "dithering" when high resolution
is not needed. For example, say you have a 1,000 line encoder and a 5
TPI leadscrew. This would give 20,000 counts per inch (0.00005").
Let's also say you need only 2,000 counts per inch (0.0005")
resolution. Using the G340 with the multiplier set to "10" would give
you that while keeping the dithering to 1/20,000 of an inch.

Mariss



--- In CAD_CAM_EDM_DRO@y..., "William Scalione" <wscalione@n...>
wrote:

>
> Mariss
>
> Reread the subject line, I think he was asking the difference
> between the 320 and 340 not the 420
>
> Bill
>
> Subject: [CAD_CAM_EDM_DRO] Re: Gecko 320 VS. 340
>
>
> > Hi,
> >
> > The G420 is a 3-phase brushless DC servodrive. In all other specs

it

> > is the same as a G320.
> >
> > I have got a few dozen hours of running time in on the prototype.
> > Right now it functions just like the G320 except there is a

noticable

> > discontinuity or "tick" on every Hall sensor edge (every 60

degrees).

> > This is something I would like to attenuate or eliminate

altogether.

> >
> > One promising idea that has ocurred to me is to phase lock a ramp
> > function off of the hall sensor edges. This ramp then would be

used

> > as an attenuation function for the "off" winding. Rather than
> > abruptly switching a winding "off" or "on", the current would be
> > gradually applied or removed, eliminating the discontinuity. The
> > behavior should then approach what one would expect from a
> > sinusoidally commutated motor.
> >
> > I have a breadboard started.
> >
> > Mariss
> >