Posted for Doug Smith <dsm...@corp.auspex.com>:
------------------------ From: "Douglas C. Smith" <dou...@concentric.net> Subject: Re: explanation of ESD events with coins in baggie. Date: Sun, 14 Mar 1999 23:42:52 -0500 (EST) To: emc-p...@ieee.org > > Well, at the risk of opening a pandora's box, I thought I > would respond to the jinjling change thread. I have not > included all the discussion to this point as it is getting > sort of long. > > I first ran into this effect in my old days at Bell Labs > where it caused interesting effects on a variety of > equipment that I tested in on. I used a common Zip-Loc bag > (quart size) with a handful of pocket change thrown in. > > I tried using a TEK SCD-5000 scope to measure the rise time > of the fields emitted as the bag was shaked. The rise time > of the wavelform was limited by the bandwidth of the scope > and small magnetic field probe, somewhat less than 100 ps > although I don't remember the exact number. > > I suppose that the mechanism is that the pieces of change > pick up different charges while rubbing the plastic bag. I > have not tried to measure the differential voltage generated > between pieces of change, but I expect it is relatively low, > maybe hundreds of volts. That would explain the fast > risetime. > > I have used a cheap AM radio ($7 variety) to demonstrate the > noise. When the bag is shaked near the radio, one hears > hundreds of discharges. And that is part of the problem, > hundreds of events, lots of possibilities to hit a > susceptibility "window" in equipment. Sort of like a whole > day's radiated ESD testing in a few tens of seconds! -:) > > I have seen all kinds of equipment affected. Most of it was > high bandwidth, but I was able to corrupt the LCD display on > a piece of consumer equipment that had only slow logic in > it. I have seen hundreds of red LEDs light up on racks of > equipment when the bag was shaken once 3 or 4 feet away. You > should have seen the face of the designer I was working with > at the time. > > Since then (~5 years ago) I have heard of many people > jingling bags of change, especially in the > telecommunications industry. > > Any more interesting stories on this phenomena out there? > > Doug Smith > Manager of EMC Development and Test > Auspex Systems (manufactures of high end servers) > work email: dsm...@auspex.com > work phone: 408-566-2157 > > --------------------------------------------------------------------- > ___ _ Doug Smith > \ / ) P.O. Box 1457 > ========= Los Gatos, CA 95031-1457 > _ / \ / \ _ Tel/Fax: 408-356-4186/408-358-3799 > / /\ \ ] / /\ \ Email 1: d...@dsmith.org > | q-----( ) | o | Email 2: d.sm...@usa.net > \ _ / ] \ _ / Email 3: d.c.sm...@ieee.org > --------------------------------------------------------------------- > > > ---------------End of Original Message----------------- -------------------------- Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA. USA 619-505-2780 List-Post: emc-pstc@listserv.ieee.org Date: 03/15/1999 Time: 07:04:12 -------------------------- --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
