Re: [CAD_CAM_EDM_DRO] AGND+DGND+EARTH=NOISE....true or false?

Jon How to use that AD620? (can I use any other OP-Amp
with high CMRR) shorting output and -ve input and
giving input at +ve input of Op-Amp????


Babar
--- Jon Elson <elson@...> wrote:

> Babar wrote:
>
> > Hi All,
> > In our Hurco Milling Servo drives are such that
> > digital and analog grounds are internally shorted
> i.e
> > DAC output of STG,tacho of motor ,limit switches
> and
> > encoder have common grounds which are then tied up
> to
> > Machine's body which is connected to earth, We are
> > facing problems of Noise I was wondering if this
> is
> > the reason ??
>
> It could be. What type of noies, ie. what are the
> symptoms?
>
> I designed a 3 to 5-axis servo drive system for my
> mill conversion, and decided to
> use common supplies for the motors and
> control/logic. I knew ground loops were
> a likely result, so i put high-quality
> instrumentation amps (Analog Devices AD620)
> on the velocity command and tachometer inputs. I
> already had used these in
> other projects, and knew they had an astounding
> capacity to reject common-mode
> noise. Even if a signal source was single ended, I
> could sense the ground potential
> at the source and remove common-mode noise that had
> coupled into the ground
> and signal wires. It has worked remarkably well.
>
> It may be good if you can break the ground at the
> milling machine, and only have
> the computer ground used for all the devices. Then,
> you can put in one heavy
> ground wire between the computer case and the Hurco
> machine base. This
> should at least simplify the ground loop situation.
>
> Jon
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES:
> http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
> aol://5863:126/rec.crafts.metalworking or go thru
> Google.com to reach it if you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I
> consider this as a sister site to the CCED group, as
> many of the same members are there, for OT subjects,
> that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC
> DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT
> ACCEPT THIS.....NO EXCEPTIONS........
>
> Post messages: CAD_CAM_EDM_DRO@yahoogroups.com
> Subscribe:
> CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe:
> CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com,
> wanliker@...
> Moderator: jmelson@...
> timg@... [Moderator]
> URL to this group:
> http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> bill,
> List Mom
> List Owner
>
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>

__________________________________________________
Do you Yahoo!?
Yahoo! News - Today's headlines
http://news.yahoo.com