On this subject, in instrumentation for example - is it best to connect 0V to MAINS EARTH or not?
If you have an instrument & sensor, where the sensor is on a long screened cable and has a metallic body - is it best to connect the screen to 0V at the instrument end AND the sensor body, or just the instrument end. If connected at both ends, the sensor body may be mains earthed - what effect does this have on the screen? Any good resources on the web explaining good screening techniques? Best Regards Darren Logan BSc(Hons) Development Engineer ------------------------------------------------------------------------------- Michell Instruments Ltd +44 (0)1223 434 854 Nuffield Close +44 (0)1223 434 895 Cambridge mailto:[EMAIL PROTECTED] CB4 1SS www.michell-instruments.com/ UKAS accredited: 0179 . ISO9002 accredited: Q6284 . Member BCAS . Investor in People ------------------------ Dew point specialists --------------------------- This communication contains information which is confidential and mayalso be privileged. It is for the exclusive use of the intended recipient(s). If you are not the intended recipient(s),please note that any distribution, copying or use of this communication or the information in it is strictly prohibited. If you have received this communication in error, please notify the sender immediately and then destroy any copies of it. -----Original Message----- Sent: 17 February 2004 10:04 To: Multiple recipients of list CHIPDIR-L On Mon, Feb 16, 2004 at 01:09:19PM -0800, Richard Purdie enlightened us thusly > > I have a CPU board with numerous IO connectors and I can't decide if I > should be worried about ground loops or not when putting it into a > metal case. > > The case will be grounded with incoming (low voltage) power. My main > concerns are the audio line in (3.5mm jack), audio out (phono/RCA) and > USB. Each comes from the CPU board with a ground line (or a screen > with USB). Should the grounds/screen on each of the connectors > electrically connect with the case or not? > > It would certainly make my life *much* easier if they could all > connect to the case. I've tried researching this but what I read > seems to conflict. Does anyone have any advice/experience? > I would keep analogue and digital grounds separate throughout, unite them at one point, and earth that point to the case. If possible, I would isolate the plugs from the case and run a ground wire. Take great care with your mountings; they are a favourite weak point, seem to attract damp, and don't rely on any techie to tidy them up the way you want. In a worst case analysis take continuous spikes being generated from a fault coming through the smoothing to ground as current pulses. You don't want that on your analogue! -- With best Regards, Declan Moriarty. -- Author: Declan Moriarty INET: [EMAIL PROTECTED] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Author: Darren Logan INET: [EMAIL PROTECTED] Fat City Hosting, San Diego, California -- http://www.fatcity.com --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
