Re: explanation of ESD events with coins in baggie.
Barry and Others, Good suggestions. I have always wanted to take a antistatic bag and shake coins, where only the coins were affected, and measure the response perhaps out of the top of the bag. Then put a non-ESD bag with coins inside a antistat bag, making sure in both cases that the coins hit each other in the same way. This series of experiments would isolate the effect of coins hitting coins only. I think Doug Smith talked about these isolation type experiments ar some point in time. How about it somebody who has the equipment? Richard Haynes 609-497-4584 -Original Message- From: Bailin Ma To: emc-p...@ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Tuesday, March 16, 1999 6:40 PM Subject: Re: explanation of ESD events with coins in baggie. >We might have to correct a misconception of triboeletrification that we >learnt from all demonstrations in schools. The myth is triboeletrification >only happens to insulators. >Can we try to say: Triboeletrification would cause transfer of electrons >between different materials. Insulators would hold electrostatic charges >due to the triboeletrification. On the other hand, transient flow of >electrons between different metals would produce broadband EMI. > >Please correct me. >Thank you. >Barry Ma > > >- >Original Text >From: , on 3/16/99 12:16 PM: >I remember a similar effect. Many years ago, when I was a student, in my >room I had a TV set with a simple loop antenna. 2 meters away from the >antenna was the radiator of the central heating of that house. On seams of >the elements of that radiator the paint had come off. Below the paint the >metal was slightly oxidized with a black colour. > >When I took a scewdriver and rubbed the metal blade along that seam the TV >picture would become distorted with some black lines. >I always wondered why, and in fact still do. > >Rene Charton > > > >- >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). > > > >- >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). > > - 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).
RE: explanation of ESD events with coins in baggie.
I just connected a wire of approx 30 cm (10") at the end of a 50 ohm coax between core and shield) and plugged into my Lecroy scope (1M) . I put a 10 dollar equivalent of Dutch money in a A4 PVC baggie and shaked the coins up and down. The most amplitude i got was when i dropped the bag in the middle of the wire . It showed up to 3 Volts tt. I did not get any apparatus upset . Relative humidity in Holland was 44 % at 21 degrees Celsius. (office temp). I repeated with a TEFLON folded baggie and got slightly more amplitude. Is it the money or is it the bag or the humidity, i did not found any interference at all on equipment under test in my test lab. The Dutch guilder is made on nickel. Regards, Gert Gremmen Ing. == Ce-test, Qualified testing == Consultants in EMC, Electrical safety and Telecommunication Compliance tests for European standards and ce-marking Member of NEC/IEC voting committee for EMC. Our Web presence: http://www.cetest.nl List of current harmonized standards http://www.cetest.nl/emc-harm.htm 15 great tips for the EMC-designer http://www.cetest.nl/features01.htm -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Tony J. O'Hara Sent: donderdag 18 maart 1999 15:58 To: INTERNET:r...@twn.tuv.com Cc: [unknown]; [unknown] Subject: Re: explanation of ESD events with coins in baggie. Ok. Not as complex as I thought-in the TV! It sounds like "simple" RF interference through the antenna. However, I have just tried shaking the "coins in a baggie" at my computer monitor - nothing! Now at a 24 year old TV on wire antennas in my basement. I got nothing at VHF frequencies (54MHz to 216MHz) but I do get some white "birdies" on UHF. There is more of them the higher I go. Highest I can get is channel 59 (746MHz). Conclusion:- the "coins in a baggie" generates high frequency RF noise, but it doesn't seem to be at a very high level. I had to be very close to the antenna, shake it real vigorously and then I didn't get many random "birdies". Maybe 20 or so over the screen!! I can get a lot more interference especially at VHF tuning, just "sparking" the wire ends coming from a 12Volt DC power supply together!! Rene, when you took a scewdriver and rubbed the metal blade along that radiator seam maybe you were slowly discharging youself of a charge generated as you walked over to it, causing sparks and hence RF. Tony O'Hara - 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). - 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).
Re: explanation of ESD events with coins in baggie.
Hi Doug, Can you give us detailed instruction for repeating your wonderful experiment? I tried jingling coins in front of some Anritsu measurement equipment. I found no effect. Thank you. Barry Ma - Original Text From: "Doug McKean" , on 3/18/99 1:40 PM: On Mon, 15 Mar 1999, Lou Gnecco wrote: > Do you get the same effect with the coins in a cloth bag or a paper bag? > Has anybody tried it? > Lou I can produce almost the same levels by jingling the same coins in my pocket. Side Note: Sorta glad my wife and I have our two boys. - 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). - 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).
Re: explanation of ESD events with coins in baggie.
On Mon, 15 Mar 1999, Lou Gnecco wrote: > Do you get the same effect with the coins in a cloth bag or a paper bag? > Has anybody tried it? > Lou I can produce almost the same levels by jingling the same coins in my pocket. Side Note: Sorta glad my wife and I have our two boys. - 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).
Re: explanation of ESD events with coins in baggie.
Ok. Not as complex as I thought-in the TV! It sounds like "simple" RF interference through the antenna. However, I have just tried shaking the "coins in a baggie" at my computer monitor - nothing! Now at a 24 year old TV on wire antennas in my basement. I got nothing at VHF frequencies (54MHz to 216MHz) but I do get some white "birdies" on UHF. There is more of them the higher I go. Highest I can get is channel 59 (746MHz). Conclusion:- the "coins in a baggie" generates high frequency RF noise, but it doesn't seem to be at a very high level. I had to be very close to the antenna, shake it real vigorously and then I didn't get many random "birdies". Maybe 20 or so over the screen!! I can get a lot more interference especially at VHF tuning, just "sparking" the wire ends coming from a 12Volt DC power supply together!! Rene, when you took a scewdriver and rubbed the metal blade along that radiator seam maybe you were slowly discharging youself of a charge generated as you walked over to it, causing sparks and hence RF. Tony O'Hara - 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).
Re: explanation of ESD events with coins in baggie.
It was 20 years ago, and now I live in a house without central heating and cable TV , so I can not reproduct that effect. But I remember for sure that the distortion similar to that which you get from spark plugs of internal combustion engines, about half a TV scan line long and repeating itself about every 3 to 5 scan lines. --- - - To: Rene Charton/TUV-Twn cc: 102630.1...@compuserve.com, emc-p...@majordomo.ieee.org Subject: Re: explanation of ESD events with coins in baggie. Rene, That is an interesting phenomenon! If you could give me a more detailed description of the TV "distortion" and "black lines" I might be able to explain at least what was happening inside the TV set (I worked many years in TV R & D). This in turn might help others to explain what ESD or EMI effect it was! For example: Are you referring to picture geometric distortion, color distortion (or was it B/W?), interference "flashes", loss of vertical or horizontal synchronization etc! Also were the "black lines" random, diagonal or what spacing etc? Also "many years ago" TV's in different countries might react differently, so where were you and about what year did you see this? Tony - 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).
Re: explanation of ESD events with coins in baggie.
Rene, That is an interesting phenomenon! If you could give me a more detailed description of the TV "distortion" and "black lines" I might be able to explain at least what was happening inside the TV set (I worked many years in TV R & D). This in turn might help others to explain what ESD or EMI effect it was! For example: Are you referring to picture geometric distortion, color distortion (or was it B/W?), interference "flashes", loss of vertical or horizontal synchronization etc! Also were the "black lines" random, diagonal or what spacing etc? Also "many years ago" TV's in different countries might react differently, so where were you and about what year did you see this? Tony - 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).
Re: explanation of ESD events with coins in baggie.
We might have to correct a misconception of triboeletrification that we learnt from all demonstrations in schools. The myth is triboeletrification only happens to insulators. Can we try to say: Triboeletrification would cause transfer of electrons between different materials. Insulators would hold electrostatic charges due to the triboeletrification. On the other hand, transient flow of electrons between different metals would produce broadband EMI. Please correct me. Thank you. Barry Ma - Original Text From: , on 3/16/99 12:16 PM: I remember a similar effect. Many years ago, when I was a student, in my room I had a TV set with a simple loop antenna. 2 meters away from the antenna was the radiator of the central heating of that house. On seams of the elements of that radiator the paint had come off. Below the paint the metal was slightly oxidized with a black colour. When I took a scewdriver and rubbed the metal blade along that seam the TV picture would become distorted with some black lines. I always wondered why, and in fact still do. Rene Charton - 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). - 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).
Re: explanation of ESD events with coins in baggie.
I remember a similar effect. Many years ago, when I was a student, in my room I had a TV set with a simple loop antenna. 2 meters away from the antenna was the radiator of the central heating of that house. On seams of the elements of that radiator the paint had come off. Below the paint the metal was slightly oxidized with a black colour. When I took a scewdriver and rubbed the metal blade along that seam the TV picture would become distorted with some black lines. I always wondered why, and in fact still do. Rene Charton - 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).
Re: explanation of ESD events with coins in baggie.
---Lou Gnecco wrote: > > Do you get the same effect with the coins in a cloth bag or a paper bag? > Has anybody tried it? > Lou > > To answer that, there are two parts; 1) Look at the triboelectric series chart. This chart, shows, what materials when rubbed with what other materials, will generate either a positive or negative charge and the relative magnitude of the charge. The materials at the top of the chart will generate a positive charge and the materials at the bottom of the chart will generate a negative charge. The farther apart the materials, the greater the charge build up. 2) Determine the conductivity of both materials. If one of the materials is a conductor, then assume that dishcharge can occur from any location. If it is an insulator, then a dicharge can only occur from the localized charged area. If one of the materials is a conductor and the second material is poor conductor such as paper or cloth, then the charge will begin decaying as soon as it is built up with a time constant based on the conductivity of the poor conductor. So, to answer your question, paper or cloth bags will have a lesser effect than a polymer bag. In certain conditions, the charge may not even built up enough to create any effects. Hans Mellberg _ DO YOU YAHOO!? Get your free @yahoo.com address at http://mail.yahoo.com - 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).
Re: explanation of ESD events with coins in baggie.
Barry, Your question is very much justified. I use the word "ESD" because in my mind, I play the image of the striking screw driver in slow motion. If you imagine the nickel surface robs the screw driver of its electrons to charge up the screw driver, then the electric field builds up as the screw driver moves away from the nickel surface to the point to cause air break down and screw driver discharge. In slow motion, this is exactly the ESD process. But in real-time, this is RF. Different perspective makes worlds of differences. :) Thanks, George Tang (Bailin Ma) wrote: > George, > > I think your reasoning is convincing to me. Thanks. > But please allow me to pose a silly question: Are we really sure those > kinds of "shaking coins" interferences can be categorized as ESD > (Electrostatic Discharge) problem? > In your experience, for instance, the screw driver did not carry any > electrostatic charge before striking the nickel surface. Right? We don't > know if coins, keys, and metal door got electrostatic charged before > jangling or slamming in Doug Mckean's experiences, either. > ASSUMING friction and striking between different materials would cause fast > electron transition between materials, back and forth, and then produce > strong RF EM waves, there is no Electrostatics involved. > If we are not sure whether or not those objects were electrostatic charged > before friction, can we try to see if it makes difference? > > Best Regards, > Barry Ma > > > - > Original Text > From: "George Tang" , on 3/15/99 4:25 PM: > Barry, > > No, I did not measure the 15kv on the scope, but I suspect that was the > case. > Here is my reasoning: The system was well shielded with aperture size > smaller > than 1/2 inch with few apertures. The system passed FCC B emi limits with > 8 dB > margin. It seemed very unlikely for a power plane in such a system to pick > up > 8 volts of radiated noise, since large power planes are not efficient > antennas. And to charge the power and ground planes with many caps up to 8 > volts at 100 MHz fundamental and GHz harmonics would seem to require very > high > power of radiated energy, assuming the lumped circuit model is used for the > caps and planes at 100 MHz. But on the other hand, the boards are grounded > to > the chassis, so if the chassis had ESD noise of many kv conducted to it, > it > could generate 8 volts on the power to ground plane. The chassis is low > impedance, so high current noise is likely. With radiated noise, even at > near > field, the propagation impedance would still be higher than conducted, so > high > current noise seemed more unlikely. The system had already passed 15kv ESD > air > (and accidental contact discharge) on most all parts on the chassis, then > the > screw driver noise maybe higher than 15 kv conducted ESD. You can see > there > are many assumptions used. But trying to measure the screw driver to > chassis > ESD voltages directly with differential probes is difficult because a large > current loop formed by the probes is required due to the moving parts and > the > probes may be damaged by the ESD. I did not measure the screw driver > voltage, > but I guessed that it was high voltage/current conducted ESD that caused > the > system error. > > Hope that helps. > > George Tang > > (Bailin Ma) wrote: > > > George, > > > > You mentioned: "the ESD generated by the metal surface was much higher > than > > 15kv." at the end of your note. > > Does that mean you measured the noise between power and ground planes > using > > digital scope, and got the higher than 15 KV reading on the scope when > > striking a screw driver against the nickel plated surface? > > > > Thank you. > > Barry Ma > > Anritsu Company > > Morgan Hill, CA 95037 > > > > - > > Original Text > > From: "George Tang" , on 3/15/99 1:23 PM: > > Douglas, > > > > I have seen similar events in a different way. Years ago, I helped > design > > an electronic system using plastic chassis with nickel surface plating. > > The > > system passed 15kv ESD air discharge and 8kv contact. But in the > hardware > > lab, the system gets data error everytime a piece of metal (like a screw > > driver) is striked against the nickel plated surface on chassis. A > digital > > scope is used to measure the noise generated on power and ground planes > on > > the PCB inside the chassis and the scope captured a noise voltage as high > > as > > 8 volts peak to peak on the PCB from a few hundred MHz to beyond GHz. > The > > PCB was very well decoupled with power next to ground planes and many on > > board capacitors. This puzzled me at first. But I remembered a very > > knowledgeable mechanical engineer once told me to never use nickel > material > > in an application where friction takes place. Nickel has a very hard and > > rough surface, so in a frictional application, it always damages the > mating > > surface. Maybe this explains the events that you saw,
Re: explanation of ESD events with coins in baggie.
George, I think your reasoning is convincing to me. Thanks. But please allow me to pose a silly question: Are we really sure those kinds of "shaking coins" interferences can be categorized as ESD (Electrostatic Discharge) problem? In your experience, for instance, the screw driver did not carry any electrostatic charge before striking the nickel surface. Right? We don't know if coins, keys, and metal door got electrostatic charged before jangling or slamming in Doug Mckean's experiences, either. ASSUMING friction and striking between different materials would cause fast electron transition between materials, back and forth, and then produce strong RF EM waves, there is no Electrostatics involved. If we are not sure whether or not those objects were electrostatic charged before friction, can we try to see if it makes difference? Best Regards, Barry Ma - Original Text From: "George Tang" , on 3/15/99 4:25 PM: Barry, No, I did not measure the 15kv on the scope, but I suspect that was the case. Here is my reasoning: The system was well shielded with aperture size smaller than 1/2 inch with few apertures. The system passed FCC B emi limits with 8 dB margin. It seemed very unlikely for a power plane in such a system to pick up 8 volts of radiated noise, since large power planes are not efficient antennas. And to charge the power and ground planes with many caps up to 8 volts at 100 MHz fundamental and GHz harmonics would seem to require very high power of radiated energy, assuming the lumped circuit model is used for the caps and planes at 100 MHz. But on the other hand, the boards are grounded to the chassis, so if the chassis had ESD noise of many kv conducted to it, it could generate 8 volts on the power to ground plane. The chassis is low impedance, so high current noise is likely. With radiated noise, even at near field, the propagation impedance would still be higher than conducted, so high current noise seemed more unlikely. The system had already passed 15kv ESD air (and accidental contact discharge) on most all parts on the chassis, then the screw driver noise maybe higher than 15 kv conducted ESD. You can see there are many assumptions used. But trying to measure the screw driver to chassis ESD voltages directly with differential probes is difficult because a large current loop formed by the probes is required due to the moving parts and the probes may be damaged by the ESD. I did not measure the screw driver voltage, but I guessed that it was high voltage/current conducted ESD that caused the system error. Hope that helps. George Tang (Bailin Ma) wrote: > George, > > You mentioned: "the ESD generated by the metal surface was much higher than > 15kv." at the end of your note. > Does that mean you measured the noise between power and ground planes using > digital scope, and got the higher than 15 KV reading on the scope when > striking a screw driver against the nickel plated surface? > > Thank you. > Barry Ma > Anritsu Company > Morgan Hill, CA 95037 > > - > Original Text > From: "George Tang" , on 3/15/99 1:23 PM: > Douglas, > > I have seen similar events in a different way. Years ago, I helped design > an electronic system using plastic chassis with nickel surface plating. > The > system passed 15kv ESD air discharge and 8kv contact. But in the hardware > lab, the system gets data error everytime a piece of metal (like a screw > driver) is striked against the nickel plated surface on chassis. A digital > scope is used to measure the noise generated on power and ground planes on > the PCB inside the chassis and the scope captured a noise voltage as high > as > 8 volts peak to peak on the PCB from a few hundred MHz to beyond GHz. The > PCB was very well decoupled with power next to ground planes and many on > board capacitors. This puzzled me at first. But I remembered a very > knowledgeable mechanical engineer once told me to never use nickel material > in an application where friction takes place. Nickel has a very hard and > rough surface, so in a frictional application, it always damages the mating > surface. Maybe this explains the events that you saw, and the ESD > generated > by the metal surface was much higher than 15kv. > > Regards, > > George Tang > > Douglas McKean wrote: > > > Hans, > > > > That's certainly an interesting explanation, but does > > not correlate to at least three different scenarios. > > > > 1) A calibrated ESD simulator in self discharge > >mode at 15KV. When the results of the ESD > >simulator are compared to the results of the > >coins, the coins have a fairly wideband constant > >level from 0 - 2 GHz. Both start off at roughly > >the same level with the only the coins remaining > >constant throughout. The ESD simulator has approx > >a -20dB per octave drop off. > > > >A side interest is that on the display of the SA has > >an IF overload ind
Re: explanation of ESD events with coins in baggie.
Do you get the same effect with the coins in a cloth bag or a paper bag? Has anybody tried it? Lou At 10:57 AM 3/15/99 -0600, you wrote: >Douglas, > >I have seen similar events in a different way. Years ago, I helped design >an electronic system using plastic chassis with nickel surface plating. The >system passed 15kv ESD air discharge and 8kv contact. But in the hardware >lab, the system gets data error everytime a piece of metal (like a screw >driver) is striked against the nickel plated surface on chassis. A digital >scope is used to measure the noise generated on power and ground planes on >the PCB inside the chassis and the scope captured a noise voltage as high as >8 volts peak to peak on the PCB from a few hundred MHz to beyond GHz. The >PCB was very well decoupled with power next to ground planes and many on >board capacitors. This puzzled me at first. But I remembered a very >knowledgeable mechanical engineer once told me to never use nickel material >in an application where friction takes place. Nickel has a very hard and >rough surface, so in a frictional application, it always damages the mating >surface. Maybe this explains the events that you saw, and the ESD generated >by the metal surface was much higher than 15kv. > > >Regards, > >George Tang > > > >Douglas McKean wrote: > >> Hans, >> >> That's certainly an interesting explanation, but does >> not correlate to at least three different scenarios. >> >> 1) A calibrated ESD simulator in self discharge >>mode at 15KV. When the results of the ESD >>simulator are compared to the results of the >>coins, the coins have a fairly wideband constant >>level from 0 - 2 GHz. Both start off at roughly >>the same level with the only the coins remaining >>constant throughout. The ESD simulator has approx >>a -20dB per octave drop off. >> >>A side interest is that on the display of the SA has >>an IF overload indication. This tells me that the >>transients from the coins are quite possibly a lot >>higher and much quicker than what the SA can handle >>within the sampling window. >> >> 2) The level from the coins is proportional to the >>dissimilarity of the metals of the coins. A bag of >>quarters has a lower profile than a bag of quarters >>and pennies. Thus, there is some function due to >>electronegativity differentials. Actually, a >>significant amount of difference. >> >> 3) I can cause the same effect by sliding the coins >>back and forth as a group within the bag. Thus, >>the coins are in at least incidental contact with >>each other so that differing potentials amongst >>the coins is minor. >> >> I'm not sure if anyone knows the reason. >> >> Regards, Doug McKean >> >> At 11:11 AM 3/11/99 -0800, Hans Mellberg wrote: >> > >> > >> >There is an expanation for this seemingly unlikely event. >> > >> >Having coins in a baggie and jingeling them causes the following >> >events to occur: >> > >> >The rubbing of a coin against the polymer causes triboelectric >> >charging of both the coin and localized areas of the bag. Since there >> >are multiple coins, each coin will charge at some voltage level but >> >not necessarily the same as another coin. When two coins of different >> >charged voltages come within dielectric breakdown distances, a >> >discharge will occur from one coin to the other in order to equalize >> >the charge distribution (q1=C1V1 and q2=C2V2. When they touch, the new >> >q1 will be C1V3 and q2= C2V3 where V3=(q1+q2)/(C1+C2)). Since coins >> >are electrically small with very small capacitances, the expected >> >discharge waveform has a very fast risetime hence the radiation at the >> >GHz region. There will also be discharges from the localized charged >> >areas of the polymer to coins of different voltages. While separating >> >two charged surfaces from each other, the voltage rises significantly >> >since the capacitance is being reduced and the conservation of charge >> >must be preserved which is the basis for tribolectric voltage >> >generation. >> >Hope that helps >> >Hans Mellberg >> > >> > >> >---b...@namg.us.anritsu.com wrote: >> >> >> >> Hi Douglas, >> >> >> >> What you described is very interesting! But I cannot understand >> >"Jingling >> >> change in a ziplock bag produces very high levels of super fast >> >transients >> >> up into the GHz range." It seems to me that jingling coins, jangling >> >keys, >> >> and slamming metal door would certainly produce acoustic waves. How >> >come >> >> they also produced electromagnetic waves? If do, under what >> >conditions? >> >> What is the mechanism to produce "very high level" of transient EM >> >waves? >> >> Did that company incorporate those kinds of "Jingling change in a >> >ziplock >> >> bag" tests into regular ESD tests for their thereafter products? >> >What is >> >> the lessen we all should learn from this particular example? >> >> >> >> Hopefully you don't think it's offens
re: explanation of ESD events with coins in baggie
Thank Doug Smith and Doug McKean of Auspex for telling us the interesting story! What we are sure from their experiences is that shaking coins in a plastic bag would produce RF waves which are strong enough to affect normal functions of variety of electronic equipment. What we are expecting is the mechanism behind the phenomenon. The explanation provided by Hans Mellberg and Doug Smith involves rubbing between coins and plastic. Can we extend it to friction between different metals? Because Doug McKean also mentioned jangling a set of keys and slamming metal door. Should we incorporate those ESD-like EM interference into EMC standards? Barry Ma - Original Text From: , on 3/15/99 9:34 AM: Posted for Doug Smith : From: "Douglas C. Smith" 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). - 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).
Re: explanation of ESD events with coins in baggie.
Douglas, I have seen similar events in a different way. Years ago, I helped design an electronic system using plastic chassis with nickel surface plating. The system passed 15kv ESD air discharge and 8kv contact. But in the hardware lab, the system gets data error everytime a piece of metal (like a screw driver) is striked against the nickel plated surface on chassis. A digital scope is used to measure the noise generated on power and ground planes on the PCB inside the chassis and the scope captured a noise voltage as high as 8 volts peak to peak on the PCB from a few hundred MHz to beyond GHz. The PCB was very well decoupled with power next to ground planes and many on board capacitors. This puzzled me at first. But I remembered a very knowledgeable mechanical engineer once told me to never use nickel material in an application where friction takes place. Nickel has a very hard and rough surface, so in a frictional application, it always damages the mating surface. Maybe this explains the events that you saw, and the ESD generated by the metal surface was much higher than 15kv. Regards, George Tang Douglas McKean wrote: > Hans, > > That's certainly an interesting explanation, but does > not correlate to at least three different scenarios. > > 1) A calibrated ESD simulator in self discharge >mode at 15KV. When the results of the ESD >simulator are compared to the results of the >coins, the coins have a fairly wideband constant >level from 0 - 2 GHz. Both start off at roughly >the same level with the only the coins remaining >constant throughout. The ESD simulator has approx >a -20dB per octave drop off. > >A side interest is that on the display of the SA has >an IF overload indication. This tells me that the >transients from the coins are quite possibly a lot >higher and much quicker than what the SA can handle >within the sampling window. > > 2) The level from the coins is proportional to the >dissimilarity of the metals of the coins. A bag of >quarters has a lower profile than a bag of quarters >and pennies. Thus, there is some function due to >electronegativity differentials. Actually, a >significant amount of difference. > > 3) I can cause the same effect by sliding the coins >back and forth as a group within the bag. Thus, >the coins are in at least incidental contact with >each other so that differing potentials amongst >the coins is minor. > > I'm not sure if anyone knows the reason. > > Regards, Doug McKean > > At 11:11 AM 3/11/99 -0800, Hans Mellberg wrote: > > > > > >There is an expanation for this seemingly unlikely event. > > > >Having coins in a baggie and jingeling them causes the following > >events to occur: > > > >The rubbing of a coin against the polymer causes triboelectric > >charging of both the coin and localized areas of the bag. Since there > >are multiple coins, each coin will charge at some voltage level but > >not necessarily the same as another coin. When two coins of different > >charged voltages come within dielectric breakdown distances, a > >discharge will occur from one coin to the other in order to equalize > >the charge distribution (q1=C1V1 and q2=C2V2. When they touch, the new > >q1 will be C1V3 and q2= C2V3 where V3=(q1+q2)/(C1+C2)). Since coins > >are electrically small with very small capacitances, the expected > >discharge waveform has a very fast risetime hence the radiation at the > >GHz region. There will also be discharges from the localized charged > >areas of the polymer to coins of different voltages. While separating > >two charged surfaces from each other, the voltage rises significantly > >since the capacitance is being reduced and the conservation of charge > >must be preserved which is the basis for tribolectric voltage > >generation. > >Hope that helps > >Hans Mellberg > > > > > >---b...@namg.us.anritsu.com wrote: > >> > >> Hi Douglas, > >> > >> What you described is very interesting! But I cannot understand > >"Jingling > >> change in a ziplock bag produces very high levels of super fast > >transients > >> up into the GHz range." It seems to me that jingling coins, jangling > >keys, > >> and slamming metal door would certainly produce acoustic waves. How > >come > >> they also produced electromagnetic waves? If do, under what > >conditions? > >> What is the mechanism to produce "very high level" of transient EM > >waves? > >> Did that company incorporate those kinds of "Jingling change in a > >ziplock > >> bag" tests into regular ESD tests for their thereafter products? > >What is > >> the lessen we all should learn from this particular example? > >> > >> Hopefully you don't think it's offensive to ask above questions. I > >am just > >> very curious. > >> > >> Thank you. > >> Best Regards, > >> Barry Ma > >> (408)778-2000 x 4465 > >> > >> - > >> Original Text > >> From: "Douglas McKean" , on 3/10/99 2:55 PM: > >> At 08:03 AM 3/8/9
Fw: Re: explanation of ESD events with coins in baggie.
Posted for Doug Smith : From: "Douglas C. Smith" 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).
Re: explanation of ESD events with coins in baggie.
Lou, It is impressive and my boss Doug Smith uses it during some of his seminars. I have tried hitting the coins in the bag with a hammer several times very near the antenna - nothing. I even smacked two big screwdrivers together on the metal near the antenna for several minutes - nothing. The piezoelectric effect is an interesting note, and I'll have to do more digging around about it. But for now, I not sure it is the mechanism. Whatever the mechanism, it is an elusive little bugger. And thanks about the info on the front end of an SA. Doug McKean At 09:03 AM 3/12/99 -0500, Lou Gnecco wrote: >Doug, >Despite the sampling window, the spectrum analyzer has a wide open >front end. It is easily saturated by broadband signals, even though you >think you are only looking at say, 100 to 200 MHz, the front end amplifiers >see everything. > >A lot of things have a piezoelectric effect, including bone and ice. >Maybe you are seeing that? Whatever it is, it's broad band. You are seeing >some extremely narrow impulses which have a wide range of frequency components. > >I have GOT to try this! > >Lou - 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).
Re: explanation of ESD events with coins in baggie.
Doug, Despite the sampling window, the spectrum analyzer has a wide open front end. It is easily saturated by broadband signals, even though you think you are only looking at say, 100 to 200 MHz, the front end amplifiers see everything. A lot of things have a piezoelectric effect, including bone and ice. Maybe you are seeing that? Whatever it is, it's broad band. You are seeing some extremely narrow impulses which have a wide range of frequency components. I have GOT to try this! Lou >Hans, > >That's certainly an interesting explanation, but does >not correlate to at least three different scenarios. > >1) A calibrated ESD simulator in self discharge > mode at 15KV. When the results of the ESD > simulator are compared to the results of the > coins, the coins have a fairly wideband constant > level from 0 - 2 GHz. Both start off at roughly > the same level with the only the coins remaining > constant throughout. The ESD simulator has approx > a -20dB per octave drop off. > > A side interest is that on the display of the SA has > an IF overload indication. This tells me that the > transients from the coins are quite possibly a lot > higher and much quicker than what the SA can handle > within the sampling window. > >2) The level from the coins is proportional to the > dissimilarity of the metals of the coins. A bag of > quarters has a lower profile than a bag of quarters > and pennies. Thus, there is some function due to > electronegativity differentials. Actually, a > significant amount of difference. > >3) I can cause the same effect by sliding the coins > back and forth as a group within the bag. Thus, > the coins are in at least incidental contact with > each other so that differing potentials amongst > the coins is minor. > >I'm not sure if anyone knows the reason. > >Regards, Doug McKean > > >At 11:11 AM 3/11/99 -0800, Hans Mellberg wrote: >> >> >>There is an expanation for this seemingly unlikely event. >> >>Having coins in a baggie and jingeling them causes the following >>events to occur: >> >>The rubbing of a coin against the polymer causes triboelectric >>charging of both the coin and localized areas of the bag. Since there >>are multiple coins, each coin will charge at some voltage level but >>not necessarily the same as another coin. When two coins of different >>charged voltages come within dielectric breakdown distances, a >>discharge will occur from one coin to the other in order to equalize >>the charge distribution (q1=C1V1 and q2=C2V2. When they touch, the new >>q1 will be C1V3 and q2= C2V3 where V3=(q1+q2)/(C1+C2)). Since coins >>are electrically small with very small capacitances, the expected >>discharge waveform has a very fast risetime hence the radiation at the >>GHz region. There will also be discharges from the localized charged >>areas of the polymer to coins of different voltages. While separating >>two charged surfaces from each other, the voltage rises significantly >>since the capacitance is being reduced and the conservation of charge >>must be preserved which is the basis for tribolectric voltage >>generation. >>Hope that helps >>Hans Mellberg >> >> >>---b...@namg.us.anritsu.com wrote: >>> >>> Hi Douglas, >>> >>> What you described is very interesting! But I cannot understand >>"Jingling >>> change in a ziplock bag produces very high levels of super fast >>transients >>> up into the GHz range." It seems to me that jingling coins, jangling >>keys, >>> and slamming metal door would certainly produce acoustic waves. How >>come >>> they also produced electromagnetic waves? If do, under what >>conditions? >>> What is the mechanism to produce "very high level" of transient EM >>waves? >>> Did that company incorporate those kinds of "Jingling change in a >>ziplock >>> bag" tests into regular ESD tests for their thereafter products? >>What is >>> the lessen we all should learn from this particular example? >>> >>> Hopefully you don't think it's offensive to ask above questions. I >>am just >>> very curious. >>> >>> Thank you. >>> Best Regards, >>> Barry Ma >>> (408)778-2000 x 4465 >>> >>> - >>> Original Text >>> From: "Douglas McKean" , on 3/10/99 2:55 PM: >>> At 08:03 AM 3/8/99 PST, Bailin Ma wrote: >>> >Hi Group, >>> > >>> >We have already seen awards for the most misleading ads, worst >>attire, >>> >worst films, . >>> >Why not awards for worst EMC and PS qualities? >>> > >>> >Barry Ma >>> >Morgan Hill, CA 95037 >>> >>> >>> Long ago in another company, I was completing the testing >>> for a large rack mounted device, i.e. emissions, immunity, >>> safety, some parts of Bellcore. We got a call from one >>> of our customers complaining about how sensitive our equipment >>> was and how susceptible it was to ESD events during their own >>> testing of our equipment. This was deemed unacceptable by them. >>> This decision of theirs jeop
Re: explanation of ESD events with coins in baggie.
Hans, That's certainly an interesting explanation, but does not correlate to at least three different scenarios. 1) A calibrated ESD simulator in self discharge mode at 15KV. When the results of the ESD simulator are compared to the results of the coins, the coins have a fairly wideband constant level from 0 - 2 GHz. Both start off at roughly the same level with the only the coins remaining constant throughout. The ESD simulator has approx a -20dB per octave drop off. A side interest is that on the display of the SA has an IF overload indication. This tells me that the transients from the coins are quite possibly a lot higher and much quicker than what the SA can handle within the sampling window. 2) The level from the coins is proportional to the dissimilarity of the metals of the coins. A bag of quarters has a lower profile than a bag of quarters and pennies. Thus, there is some function due to electronegativity differentials. Actually, a significant amount of difference. 3) I can cause the same effect by sliding the coins back and forth as a group within the bag. Thus, the coins are in at least incidental contact with each other so that differing potentials amongst the coins is minor. I'm not sure if anyone knows the reason. Regards, Doug McKean At 11:11 AM 3/11/99 -0800, Hans Mellberg wrote: > > >There is an expanation for this seemingly unlikely event. > >Having coins in a baggie and jingeling them causes the following >events to occur: > >The rubbing of a coin against the polymer causes triboelectric >charging of both the coin and localized areas of the bag. Since there >are multiple coins, each coin will charge at some voltage level but >not necessarily the same as another coin. When two coins of different >charged voltages come within dielectric breakdown distances, a >discharge will occur from one coin to the other in order to equalize >the charge distribution (q1=C1V1 and q2=C2V2. When they touch, the new >q1 will be C1V3 and q2= C2V3 where V3=(q1+q2)/(C1+C2)). Since coins >are electrically small with very small capacitances, the expected >discharge waveform has a very fast risetime hence the radiation at the >GHz region. There will also be discharges from the localized charged >areas of the polymer to coins of different voltages. While separating >two charged surfaces from each other, the voltage rises significantly >since the capacitance is being reduced and the conservation of charge >must be preserved which is the basis for tribolectric voltage >generation. >Hope that helps >Hans Mellberg > > >---b...@namg.us.anritsu.com wrote: >> >> Hi Douglas, >> >> What you described is very interesting! But I cannot understand >"Jingling >> change in a ziplock bag produces very high levels of super fast >transients >> up into the GHz range." It seems to me that jingling coins, jangling >keys, >> and slamming metal door would certainly produce acoustic waves. How >come >> they also produced electromagnetic waves? If do, under what >conditions? >> What is the mechanism to produce "very high level" of transient EM >waves? >> Did that company incorporate those kinds of "Jingling change in a >ziplock >> bag" tests into regular ESD tests for their thereafter products? >What is >> the lessen we all should learn from this particular example? >> >> Hopefully you don't think it's offensive to ask above questions. I >am just >> very curious. >> >> Thank you. >> Best Regards, >> Barry Ma >> (408)778-2000 x 4465 >> >> - >> Original Text >> From: "Douglas McKean" , on 3/10/99 2:55 PM: >> At 08:03 AM 3/8/99 PST, Bailin Ma wrote: >> >Hi Group, >> > >> >We have already seen awards for the most misleading ads, worst >attire, >> >worst films, . >> >Why not awards for worst EMC and PS qualities? >> > >> >Barry Ma >> >Morgan Hill, CA 95037 >> >> >> Long ago in another company, I was completing the testing >> for a large rack mounted device, i.e. emissions, immunity, >> safety, some parts of Bellcore. We got a call from one >> of our customers complaining about how sensitive our equipment >> was and how susceptible it was to ESD events during their own >> testing of our equipment. This was deemed unacceptable by them. >> This decision of theirs jeopardized a sale of several million >> dollars. The finger was duly pointed by everyone right to yours >> truly. My head was literally in no uncertain terms put on the block. >> >> I contested producing repeatable and acceptable ESD test results >> that were BELOW the BER levels specified by Bellcore with ESD test >> levels ABOVE that specified by the test standard. I wanted as much >> margin as possible for our product. >> >> Well, it ended up that if you stood three to four feet in front of >> the rack and jingled change in your pocket or jangled a set of keys >> in front of it, the product would RESET. Jingling c
RE: explanation of ESD events with coins in baggie.
I would recommend that Doug Smith of Auspex Systems answer this one as he has presented this at an ANSI C63 ESD meeting and to the FAA.(He managed to crash their computers)!! Thank you Charles Grasso Advisory Engineer StorageTek 2270Sth 88th Street Louisville CO 80027 M/S 4247. Tel:303-673-2908 Fax:303-661-7115 email:gra...@louisville.stortek.com Web Site: http://www.ewh.ieee.org/r5/denver/rockymountainemc/ -Original Message- From: Hans Mellberg [mailto:emcconsult...@yahoo.com] Sent: Thursday, March 11, 1999 12:11 PM To: emc-p...@ieee.org Subject: Re: explanation of ESD events with coins in baggie. There is an expanation for this seemingly unlikely event. Having coins in a baggie and jingeling them causes the following events to occur: The rubbing of a coin against the polymer causes triboelectric charging of both the coin and localized areas of the bag. Since there are multiple coins, each coin will charge at some voltage level but not necessarily the same as another coin. When two coins of different charged voltages come within dielectric breakdown distances, a discharge will occur from one coin to the other in order to equalize the charge distribution (q1=C1V1 and q2=C2V2. When they touch, the new q1 will be C1V3 and q2= C2V3 where V3=(q1+q2)/(C1+C2)). Since coins are electrically small with very small capacitances, the expected discharge waveform has a very fast risetime hence the radiation at the GHz region. There will also be discharges from the localized charged areas of the polymer to coins of different voltages. While separating two charged surfaces from each other, the voltage rises significantly since the capacitance is being reduced and the conservation of charge must be preserved which is the basis for tribolectric voltage generation. Hope that helps Hans Mellberg ---b...@namg.us.anritsu.com wrote: > > Hi Douglas, > > What you described is very interesting! But I cannot understand "Jingling > change in a ziplock bag produces very high levels of super fast transients > up into the GHz range." It seems to me that jingling coins, jangling keys, > and slamming metal door would certainly produce acoustic waves. How come > they also produced electromagnetic waves? If do, under what conditions? > What is the mechanism to produce "very high level" of transient EM waves? > Did that company incorporate those kinds of "Jingling change in a ziplock > bag" tests into regular ESD tests for their thereafter products? What is > the lessen we all should learn from this particular example? > > Hopefully you don't think it's offensive to ask above questions. I am just > very curious. > > Thank you. > Best Regards, > Barry Ma > (408)778-2000 x 4465 > > - > Original Text > From: "Douglas McKean" , on 3/10/99 2:55 PM: > At 08:03 AM 3/8/99 PST, Bailin Ma wrote: > >Hi Group, > > > >We have already seen awards for the most misleading ads, worst attire, > >worst films, . > >Why not awards for worst EMC and PS qualities? > > > >Barry Ma > >Morgan Hill, CA 95037 > > > Long ago in another company, I was completing the testing > for a large rack mounted device, i.e. emissions, immunity, > safety, some parts of Bellcore. We got a call from one > of our customers complaining about how sensitive our equipment > was and how susceptible it was to ESD events during their own > testing of our equipment. This was deemed unacceptable by them. > This decision of theirs jeopardized a sale of several million > dollars. The finger was duly pointed by everyone right to yours > truly. My head was literally in no uncertain terms put on the block. > > I contested producing repeatable and acceptable ESD test results > that were BELOW the BER levels specified by Bellcore with ESD test > levels ABOVE that specified by the test standard. I wanted as much > margin as possible for our product. > > Well, it ended up that if you stood three to four feet in front of > the rack and jingled change in your pocket or jangled a set of keys > in front of it, the product would RESET. Jingling change in a ziplock > bag produces very high levels of super fast transients up into the GHz > range. Worse, slamming the metal door to the lab in which the equipment > was setup would also reset the product. The lab door was say 20 or so > feet from our equipment under test. It took six months of a redesign > cycle to straighten out that one, but it was finally done. > > I always wanted to find out who in God's name could have come > up with such an insidious ESD test by simply putting some change > in a zip lock bag and jingling it in front of equipment. > But, I figured "he", whoever he w
Re: explanation of ESD events with coins in baggie.
There is an expanation for this seemingly unlikely event. Having coins in a baggie and jingeling them causes the following events to occur: The rubbing of a coin against the polymer causes triboelectric charging of both the coin and localized areas of the bag. Since there are multiple coins, each coin will charge at some voltage level but not necessarily the same as another coin. When two coins of different charged voltages come within dielectric breakdown distances, a discharge will occur from one coin to the other in order to equalize the charge distribution (q1=C1V1 and q2=C2V2. When they touch, the new q1 will be C1V3 and q2= C2V3 where V3=(q1+q2)/(C1+C2)). Since coins are electrically small with very small capacitances, the expected discharge waveform has a very fast risetime hence the radiation at the GHz region. There will also be discharges from the localized charged areas of the polymer to coins of different voltages. While separating two charged surfaces from each other, the voltage rises significantly since the capacitance is being reduced and the conservation of charge must be preserved which is the basis for tribolectric voltage generation. Hope that helps Hans Mellberg ---b...@namg.us.anritsu.com wrote: > > Hi Douglas, > > What you described is very interesting! But I cannot understand "Jingling > change in a ziplock bag produces very high levels of super fast transients > up into the GHz range." It seems to me that jingling coins, jangling keys, > and slamming metal door would certainly produce acoustic waves. How come > they also produced electromagnetic waves? If do, under what conditions? > What is the mechanism to produce "very high level" of transient EM waves? > Did that company incorporate those kinds of "Jingling change in a ziplock > bag" tests into regular ESD tests for their thereafter products? What is > the lessen we all should learn from this particular example? > > Hopefully you don't think it's offensive to ask above questions. I am just > very curious. > > Thank you. > Best Regards, > Barry Ma > (408)778-2000 x 4465 > > - > Original Text > From: "Douglas McKean" , on 3/10/99 2:55 PM: > At 08:03 AM 3/8/99 PST, Bailin Ma wrote: > >Hi Group, > > > >We have already seen awards for the most misleading ads, worst attire, > >worst films, . > >Why not awards for worst EMC and PS qualities? > > > >Barry Ma > >Morgan Hill, CA 95037 > > > Long ago in another company, I was completing the testing > for a large rack mounted device, i.e. emissions, immunity, > safety, some parts of Bellcore. We got a call from one > of our customers complaining about how sensitive our equipment > was and how susceptible it was to ESD events during their own > testing of our equipment. This was deemed unacceptable by them. > This decision of theirs jeopardized a sale of several million > dollars. The finger was duly pointed by everyone right to yours > truly. My head was literally in no uncertain terms put on the block. > > I contested producing repeatable and acceptable ESD test results > that were BELOW the BER levels specified by Bellcore with ESD test > levels ABOVE that specified by the test standard. I wanted as much > margin as possible for our product. > > Well, it ended up that if you stood three to four feet in front of > the rack and jingled change in your pocket or jangled a set of keys > in front of it, the product would RESET. Jingling change in a ziplock > bag produces very high levels of super fast transients up into the GHz > range. Worse, slamming the metal door to the lab in which the equipment > was setup would also reset the product. The lab door was say 20 or so > feet from our equipment under test. It took six months of a redesign > cycle to straighten out that one, but it was finally done. > > I always wanted to find out who in God's name could have come > up with such an insidious ESD test by simply putting some change > in a zip lock bag and jingling it in front of equipment. > But, I figured "he", whoever he was, was lost in time. > > And wouldn't you know it? ... > > I now work for that man. > > > - > 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). > > > > - > 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). > > _ DO YOU YAHOO!? Get your fre
