RE: [CAD_CAM_EDM_DRO] Re: Pixie error connection

A hexfet is probably a bit of overkill really Brian, a simple logic level
fet would do all he needs, and I suppose fets are easier than transitors,
but most people know a little about transitors, and Fets are black magic to
new comers.



I do use a lot of the VNP series fets, these are logic level triggered but
short circuit proof. I put dozens of these in my marine steering sytems onto
a heatsink. They only get hot when they are short circuit on the output.
It's amazing how many Indian and Chinese docks phone up to say the heatsink
is hot, well me thinks that's more smoke saved.



Regs Mark





Dr. Mark Vaughan Ph'D. B.Eng. M0VAU

Managing Director

Vaughan Industries Ltd, reg in UK no 2561068

Water Care Technology Ltd, reg in UK no 4129351

Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
Phone/Fax 44 1872 561288

RSGB DRM111(Cornwall)

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of BRIAN FOLEY
Sent: 15 July 2007 20:03
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Re: Pixie error connection



Hi, sounds like a job for a hexfet to boost the level. cul brian f.

----- Original Message -----
From: "Tom Hubin" <thubin@earthlink. <mailto:thubin%40earthlink.net> net>
To: <CAD_CAM_EDM_ <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>
DRO@yahoogroups.com>
Sent: Sunday, July 15, 2007 1:59 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Pixie error connection

> Hello Mark,
>
> Open collector outputs will sometimes drive a relay. One end of the
> relay coil goes to the open collector output and the other end of the
> coil goes to +5v...not to ground. The open collector can sink current
> but sources nothing. The pullup resistor, if it is there, is the source
> for +5v and that is rarely enough to drive a relay coil, although may be
> enough to drive a solid state relay.
>
> Try to find out what the open collector device is and the max current
> that it can sink when the output is low. Then use a relay coil or solid
> state relay that requires less than that. Just be sure that the relay
> input that is not tied to the open collector is tied to +5v.
>
> Sometimes you can tie it to +12v instead of +5v but that requires more
> info to decide.
>
> Tom Hubin
> thubin@earthlink. <mailto:thubin%40earthlink.net> net
>
> **************************
>
> toolspindoctor wrote:
> >
> > Mark,
> >
> > I appreciate your input! I had envisioned the Pixie error circuit as
> > you described. I still don't understand why the error output would not
> > be sufficient to drive a DC solid state relay. When I connect the
> > error to the relay is just goes into an error state. There must be
> > something different about the open collector, which I don't
> > understand. Jim Cullins, who designed my breakout board has suggested
> > interfacing with an IC with Darlington arrays.
> >
> > I have all the safeguards with limit switches etc. The system shuts
> > down everything during an estop coming from my servo amps or from
> > Mach3, the estop switch etc. However, the final protection is to get
> > the servo amps to shut off (signal the Mach3-Campbell estop)when the
> > Pixies fail. Now of course, the Pixies go into an error condition
> > without triggering an estop.
> >
> > Thanks again,
> > Keith
> >
> > --- In CAD_CAM_EDM_ <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>
DRO@yahoogroups.com, "Mark Vaughan" <mark@...>
> > wrote:
> > >
> > > The pixie error output is am open collector output, and an input
> > with pull
> > > up resistors. What this means is each pixie card has a little
> > transistor
> > > switch that switches the line to 0V when there is an error. When
> > there isn't
> > > an error the pull up resistor keeps the output at 5V, but being a
> > resistor
> > > it is low current. The idea is that you can wire all the pixie card
> > error
> > > wires together so which ever one faults pulls the line of all the
> > others to
> > > 0V which the others see as an input and stop themselves so when it
> > goes
> > > wrong all pixie cards will stop so there will be no axis movement.
> > >
> > > As to interfacing to other systems, the output can only drive 5V
> > logic,
> >
> >
>
>
>
> Addresses:
> FAQ: http://www.ktmarket <http://www.ktmarketing.com/faq.html>
ing.com/faq.html
> FILES: http://groups.
<http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/>
yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_ <mailto:CAD_CAM_EDM_DRO%40yahoogroups.com>
DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_
<mailto:CAD_CAM_EDM_DRO-subscribe%40yahoogroups.com>
DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_
<mailto:CAD_CAM_EDM_DRO-unsubscribe%40yahoogroups.com>
DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_ <mailto:CAD_CAM_EDM_DRO-owner%40yahoogroups.com>
DRO-owner@yahoogroups.com, wanliker@aol. <mailto:wanliker%40aol.com> com,
timg@ktmarketing. <mailto:timg%40ktmarketing.com> com
> Moderator: pentam@cncKITS. <mailto:pentam%40cncKITS.com> com
indigo_red@qwest. <mailto:indigo_red%40qwest.net> net davemucha@juno.
<mailto:davemucha%40juno.com> com
[Moderators]
> URL to this group: http://groups.
<http://groups.yahoo.com/group/CAD_CAM_EDM_DRO>
yahoo.com/group/CAD_CAM_EDM_DRO
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/ <aol://5863:126/rec.crafts.metalworking>
rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalwor <http://www.metalworking.com/news_servers.html>
king.com/news_servers.html
>
> http://groups. <http://groups.yahoo.com/group/jobshophomeshop>
yahoo.com/group/jobshophomeshop I consider this to be 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........
> bill
> List Mom
> List Owner
>
>
> Yahoo! Groups Links
>
>
>
>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.476 / Virus Database: 269.10.6/902 - Release Date: 7/15/07
2:21 PM
>
>





[Non-text portions of this message have been removed]