I've often wondered... Most people who have an ESD gun have a spectrum analyzer.
Most ESD guns have a multiple discharge setting. What if you made a "coupling strip", such as a 12 inch long x 1 inch wide piece of copper tape mounted on a board; then used two 970 Ohm resistors to bond the strip to the ground reference plane (probably would want to make this connection with some kind of clip so you could connect/disconnect easily); then set up a jig which would hold a coax near field probe (the homemade kind with the end cut and the center conductor protruding a little bit) a fixed distance from this coupling strip. It seems that you could take your freshly calibrated ESD gun and discharge to the strip with your spectrum analyzer set on peak hold and a span covering 100 to 1000Mhz. You could make a number of discharges, say 10 or 20. Then you would have a "spectral signature" of your freshly calibrated ESD gun. Couldn't you then repeat the process daily and compare the signature to the original? Sorry that I haven't done this myself. I just thought of this idea this morning. Can any of the group's gurus see a hole in this idea? Chris Maxwell Design Engineer Nettest From: [email protected] [mailto:[email protected]] On Behalf Of Brian Epstein Sent: Thursday, April 22, 2004 4:16 PM To: [email protected]; [email protected]; [email protected] Cc: [email protected] Subject: RE: ESD Gun Verification between calibrations That actually works. Just zap the inside of your arm and measure the welt. -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: Thu 4/22/2004 11:18 AM To: [email protected]; [email protected] Cc: [email protected] Subject: RE: ESD Gun Verification between calibrations I often test 9 volt batteries with my tongue. A similar technique can be used to test the ESD gun. Just discharge it to your arm and gage the performance by how it feels. Just kidding, sort of. Dave Cuthbert -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Gordon,Ian Sent: Thursday, April 22, 2004 1:46 AM To: Kevin Harris Cc: EMC-PSTC ([email protected]) Subject: RE: ESD Gun Verification between calibrations Kevin You are only verifying that the equipment is working so there is no need to check absolute levels or waveforms etc, that is the function of the calibration. Our EMC lab has been assessed to ISO 17025 by TUV International and they are satisfied with the following procedure which is extracted from our EMC lab Quality Manual. In our in-house EMC reports (which TUV are prepared to endorse) we record the latest date of calibration. Following the next calibration we assess whether there is a requirement to repeat any work based on the outcome of that calibration i.e. if the device is outside the manufacturers specification we repeat the work performed in the intervening period. 1. EQUIPMENT USED FOR BS EN 61000-4-2 a) Electro-static discharge gun S/N: 2494 In house equipment No. 9853-22-998 METHOD: 1. Configure item a as per section 6.5 of EMC lab instruction manual. (Details configuration as per manufacturers instructions) 2. Set the ESD gun to 8kV air discharge, single shot. 3. Attempt to discharge the gun to the insulating block (a block of wood 100 x 150 x 700mm) on the earth plane. 4. Check that a discharge did not occur by observing no audible signal from the gun and the display of the gun indicates 0.0kV. 5. Attempt to discharge the gun to the earth plane. 6. Check that a discharge did occur by observing an audible signal from the gun and the display of the gun indicates over 6kV. 7. Update the Equipment checklist spreadsheet to show that these pieces of equipment are functioning correctly. Ian Gordon -----Original Message----- From: Ken Javor [mailto:[email protected]] Sent: 21 April 2004 20:51 To: Kevin Harris; EMC-PSTC ([email protected]) Subject: Re: ESD Gun Verification between calibrations Never done this before, so this is shooting from the hip. If you have a receiver, as opposed to an analyzer, you could, using sufficient attenuation, drive the input directly or using some transducer to measure the spectral signature from dc to daylight right after calibration, and run checks against that for intermediate checks. If you have an analyzer with even rudimentary preselection, you can do the same. Obviously you would have to use the max hold function and run multiple shots. I don't know how fast those things recharge - if it takes a long time that would make this technique impractical. From: Kevin Harris <[email protected]> Reply-To: Kevin Harris <[email protected]> Date: Wed, 21 Apr 2004 11:51:04 -0400 To: "EMC-PSTC ([email protected])" <[email protected]> Subject: ESD Gun Verification between calibrations Dear Colleagues, We are in the process of moving some of the ESD testing we currently do (as pre-compliance to formal testing at an agency or test house) to formal testing under a laboratory accreditation program. In that regard, the issue of verification of the ESD gun's performance has come up between calibration cycles. Short of spending a lot of coin on a scope with a very fast one shot capture and running the formal calibration test as a method of periodic verification, does anyone have some suggestions for alternative methods that aren't so expensive but would still satisfy an accreditor as being a reasonable approach. Thanks Kind Regards, Kevin Harris Manager, Approvals Group Digital Security Controls 3301 Langstaff Road Concord, Ontario CANADA L4K 4L2 Tel: +1 905 760 3000 Ext. 2378 Fax +1 905 760 3020 Email: [email protected] _____________________________________________________________________ This e-mail has been scanned for viruses by MCI's Internet Managed Scanning Services - powered by MessageLabs. For further information visit http://www.mci.com *********************************************************************** This email is confidential and intended solely for the use of the individual to whom it is addressed. Any views or opinions presented are solely those of the author and do not necessarily represent those of the BOC Group plc or any of its affiliates. If you are not the intended recipient, be advised that you have received this email in error and that any use, dissemination, forwarding, printing, or copying of this email is strictly prohibited. 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