Post by thread:[EE]:Lightning

I have in the past used an ESD gun to simulate the effects of an ESD discharge. I believe it will simulate a small quick lightning discharge. I can get more specifics on it for you if you want me to. Let me know. I do know they're not real cheap, and I don't know for sure if you can rent or lease them I suppose you probably can, but I don't know what vendor. Let me know. Regards, Jim On Mon, 31 July 2000, Shawn Yates wrote: {Quote hidden}> > I need to test some products for lightning resistance. Is there any > type of test equipment which will simulate the ESD generated by a lightning > strike? I need to simulate the effect of a lightning strike in the vicinity > of the product, not the effect of a direct hit. > > Thanks > > Shawn > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. spam_OUTjimTakeThisOuTjpes.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Sure, send me what you have please. -----Original Message----- From: James Paul [.....jimKILLspam@spam@JPES.COM] Sent: Monday, July 31, 2000 2:55 PM To: PICLISTKILLspamMITVMA.MIT.EDU Subject: Re: [EE]:Lightning I have in the past used an ESD gun to simulate the effects of an ESD discharge. I believe it will simulate a small quick lightning discharge. I can get more specifics on it for you if you want me to. Let me know. I do know they're not real cheap, and I don't know for sure if you can rent or lease them I suppose you probably can, but I don't know what vendor. Let me know. Regards, Jim On Mon, 31 July 2000, Shawn Yates wrote: > > I need to test some products for lightning resistance. Is there any > type of test equipment which will simulate the ESD generated by a lightning > strike? I need to simulate the effect of a lightning strike in the vicinity > of the product, not the effect of a direct hit. > > Thanks > > Shawn > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. .....jimKILLspam.....jpes.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Shawn Yates wrote: > I need to test some products for lightning resistance. Is there any >type of test equipment which will simulate the ESD generated by a lightning >strike? I need to simulate the effect of a lightning strike in the vicinity >of the product, not the effect of a direct hit. > Unless you want to pull a Ben Franklin [flying a kite in a thunderstorm], you might check into using an ESD gun, like James Paul said. Several years back, I did some ESD testing on some embedded controllers for a company using a Schaffner gun - the state of the art, AFAIK. Quite nice - you could dial in KV and #spikes/sec. Looked like a big 44 magnum, had a nice insulated handle, and some fixtures for holding the spark distance constant/etc. Oh boy, could you draw an arc at 20 KV or so - and really latch up a controller chip. [the cat didn't like it much, however]. The company rented the gun for short periods of time from some rental house ???????? There are various ESD standard models/etc. Might try the following: http://www.google.com - search on "ESD gun" For overview, try: http://www.ednmag.com/reg/1997/060597/12df_03.htm I also have a few links at: http://www.sni.net/~oricom/teklink2.htm best regards, - Dan Michaels Oricom Technologies =================== -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

At 11:54 AM 7/31/00 -0700, James Paul wrote: > I have in the past used an ESD gun to simulate the effects of an ESD > discharge. I believe it will simulate a small quick lightning > discharge. I can get more specifics on it for you if you want me > to. Let me know. I do know they're not real cheap, and I don't > know for sure if you can rent or lease them I suppose you probably > can, but I don't know what vendor. Let me know. I built an upset tester, which I think is what you're looking for, in an afternoon. It's an absolutely lethal device, never run in a room with the door open, or without a "watcher" who can save the operator in case of shock. Large plate of PCB material. 12V monitor flyback supply, adjustable from 10-20kV Three 0.033uF 30kV caps (hard to find) One 40 meg resistor. The flyback supply charges the cap through the resistor, There is a focus pulloff in mine, which also discharges the cap (slowly) once power is off, I added a neon and resistor to that, to indicate charge on the output cap. Everything is mounted to the PCB material, and grounded to it. Build a spark gap, variable distance, 1/4 to about 3/4 inch works well. I used #12 copper wire with a long nylon screw set to move the GROUND side of the gap closer and farther. Charge one cap (you will have to vary what I used to what you can find) till discharge through the gap. This will cause a huge surge of current, which will upset various microprocessor devices. (Wear hearing protection, the discharge is similar to small arms fire in volume, though much sharper) The way I test is to use repetitive discharges, and bring the device closer and closer till it upsets. You can add a coil of a turn or two to get more field strength, vary as needed. It's no good for absolute measurements, but works well for "is this better or worse" measurements, and only cost about $50 in materials to build. One hand rule applies, this is a dangerous device. -- http://www.SpamWhack.com A pre-emptive strike against spam Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 My transistor sings with unintended parasitic the smoke escapes By Jeff Stout -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

A super cheap ESD Gun can be made by getting one of those Grill Lighters that has a built in Piezo ignitator. Run it out of propane, remove the shield, and you have a lower power ESD gun. Not exactly calibrated but its a good for a rough idea of how something stands up to ESD. -Ben At 11:54 AM 7/31/00 -0700, you wrote: {Quote hidden}> I have in the past used an ESD gun to simulate the effects of an ESD > discharge. I believe it will simulate a small quick lightning > discharge. I can get more specifics on it for you if you want me > to. Let me know. I do know they're not real cheap, and I don't > know for sure if you can rent or lease them I suppose you probably > can, but I don't know what vendor. Let me know. > > > Regards, > > Jim > > > > >On Mon, 31 July 2000, Shawn Yates wrote: > >> >> I need to test some products for lightning resistance. Is there any >> type of test equipment which will simulate the ESD generated by a lightning >> strike? I need to simulate the effect of a lightning strike in the vicinity {Quote hidden}>> of the product, not the effect of a direct hit. >> >> Thanks >> >> Shawn >> >> -- >> http://www.piclist.com hint: The PICList is archived three different >> ways. See http://www.piclist.com/#archives for details. > >EraseMEjimspam_OUTTakeThisOuTjpes.com > >-- >http://www.piclist.com hint: The PICList is archived three different >ways. See http://www.piclist.com/#archives for details. > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

I have been reading about that approach. But does that simulate more the ESD from the static shock of a person touching a device (which does not happen to my products because they are mounted on the ceiling), or would it be similar to the charges and fields caused by a nearby lightning strike? Everything I read tends to talk about charges built up by seperating materials (ie static shock) which is not exactly what i am after. Does lightning cause an ESD, EFT or low power EMP or all of those? Thanks for all the input. I am also reading about making a tesla coil or van de graaff generator and shocking the comm wire with it. All other ideas welcome. Shawn {Original Message removed}

> >Does lightning cause an ESD, EFT or low power EMP or all of those? > >Thanks for all the input. I am also reading about making a tesla coil or >van de graaff generator and shocking the comm wire with it. All other ideas >welcome. A direct hit causes vaporisation :) Near field hits give you a magnetic pulse, which is why I built the tester that I did. This magnetic pulse induces current into your wires and tracks, and if large enough, can cause failures. You may also get some voltage in on cables and such, either magnetically induced, or leakage from the strike itself. -- http://www.SpamWhack.com A pre-emptive strike against spam Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 My transistor sings with unintended parasitic the smoke escapes By Jeff Stout -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

29/7/2000 I think that it is time to take a step back and look at what you are attempting to design and test against. ESD guns do just that, nothing else! Are you looking at conducted or induced lightning currents? Are they of the near or far type? If you have to protect against lightning, then do you also have to protect against mains? (Often this answer is yes). What is the rise time and expected power of the waveform that you have to test against? 10uS 10kV by 10 applications?. If this is so then there are many devices available off the shelf that will protect against this (some are better than others some have a tendency to explode). Take a look at UL1529? telecom stuff Find what you have to protect against first, else you have no base on which to test against. Dennis > {Original Message removed}

{Quote hidden}> -----Original Message----- > From: David VanHorn [SMTP:dvanhornspam_OUTCEDAR.NET] > Sent: Monday, July 31, 2000 10:35 PM > To: @spam@PICLISTKILLspamMITVMA.MIT.EDU > Subject: Re: [EE]:Lightning > > At 11:54 AM 7/31/00 -0700, James Paul wrote: > > I have in the past used an ESD gun to simulate the effects of an ESD > > discharge. I believe it will simulate a small quick lightning > > discharge. I can get more specifics on it for you if you want me > > to. Let me know. I do know they're not real cheap, and I don't > > know for sure if you can rent or lease them I suppose you probably > > can, but I don't know what vendor. Let me know. > > > I built an upset tester, which I think is what you're looking for, in an > afternoon. > > It's an absolutely lethal device, never run in a room with the door open, > or without a "watcher" who can save the operator in case of shock. > > Large plate of PCB material. 12V monitor flyback supply, adjustable from > 10-20kV > Three 0.033uF 30kV caps (hard to find) > One 40 meg resistor. > > The flyback supply charges the cap through the resistor, There is a focus > pulloff in mine, which also discharges the cap (slowly) once power is off, > I added a neon and resistor to that, to indicate charge on the output cap. > Everything is mounted to the PCB material, and grounded to it. > > Build a spark gap, variable distance, 1/4 to about 3/4 inch works well. I > used #12 copper wire with a long nylon screw set to move the GROUND side > of > the gap closer and farther. > > Charge one cap (you will have to vary what I used to what you can > find) till discharge through the gap. > This will cause a huge surge of current, which will upset various > microprocessor devices. > (Wear hearing protection, the discharge is similar to small arms fire in > volume, though much sharper) > > The way I test is to use repetitive discharges, and bring the device > closer > and closer till it upsets. > You can add a coil of a turn or two to get more field strength, vary as > needed. > > It's no good for absolute measurements, but works well for "is this better > or worse" measurements, and only cost about $50 in materials to build. > > One hand rule applies, this is a dangerous device. > Is it FCC compliant? <g> Mike -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu>

I was involved in some line powered lightning protection work in the past. History: Some (70?) years ago, General Electric built AC powered clocks. They failed in the field on a regular basis. This made customers unhappy. GE set out to find out how to stop the failures. They found that having the clock insulation system able to withstand an impulse of 1.2us x 50us at 5 KV peak reduced the failure rate to a level acceptable by customers. 1) The circuit using the adjustable spark gap is the way to go. We had a similar test setup in use for GFCI validation. 2) There was a hand held line voltage monitor (Wiggington Tester?) that had a coil in it that when touched to the mains supply caused much horrible transients. Be sure to have the impulse riding on top of the mains and be able to change the phase at which the gap fires. (A triggered gap would be best. Somewhere I have a schematic of the 'beast'. It really is a literal "killer". As a newbeeee. I hope I have not offended. kb They're just Jealous That the Voices Don't talk to Them. {Original Message removed}

>There was a hand held line voltage monitor (Wiggington Tester?) that >had a coil in it that when touched to the mains supply caused much horrible >transients. I have seen this done with a small fluorescent light box that had a couple of 12 or 15 inch tubes in it. At once stage this also got used a mains impulse test unit by switching it off and rapidly. I saw it used to upset a peripheral on a PDP11 machine which had a not very well shielded peripheral. The resulting error messages hung the processor up to a point where it had to be rebooted to clear the backlog of messages.... -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu>

If you don't need a regulated static source, you can use one of the portable protection devices to generate quite an arc. We used one of them (in addition to an ESD gun) to test a portable pic device. They are about the size of a calculator, with a couple of metal probes on one end. When you press a button, they generate a constant stream of arcs between the probes. This may be too much ESD, but it can give a rough idea if it is static sensitive by just holding it close to the circuit without arcing through it. We got one in a sporting goods store. Howard At 03:14 PM 7/31/00 -0600, you wrote: >Shawn Yates wrote: > > I need to test some products for lightning resistance. Is there any > >type of test equipment which will simulate the ESD generated by a lightning > >strike? I need to simulate the effect of a lightning strike in the vicinity > >of the product, not the effect of a direct hit. > > -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestspamBeGonemitvma.mit.edu>

Dave Van Horn wrote: > >I built an upset tester, which I think is what you're looking for, in an >afternoon. > >It's an absolutely lethal device, never run in a room with the door open, >or without a "watcher" who can save the operator in case of shock. > >Large plate of PCB material. 12V monitor flyback supply, adjustable from >10-20kV >Three 0.033uF 30kV caps (hard to find) >One 40 meg resistor. > ........ >One hand rule applies, this is a dangerous device. > Yeah, I did something like this a while back - used the HV ckt from an old TV set. As you say, this sorta thing is **lethal** - and what makes it especially so is the amount of current that can be transferred. One single 40M resistor is not very safe, as the spark can usually jump it, and you lose the current limiting ---> resulting in death. I used about a dozen resistors in series [forget the value, but probably about 1-5M]. The spark would typically jump across 1 or 2, but not the entire string. [this stuff is not for the faint of heart]. - danM -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestEraseMEspam_OUTmitvma.mit.edu>

Shawn Yates wrote: >I have been reading about that approach. But does that simulate more the >ESD from the static shock of a person touching a device (which does not >happen to my products because they are mounted on the ceiling), or would it >be similar to the charges and fields caused by a nearby lightning strike? >Everything I read tends to talk about charges built up by seperating >materials (ie static shock) which is not exactly what i am after. > You need to do some backgnd reading regarding difference between lightning and ESD - I did it a while back but forget the exact details. True lightning, of course, travels at something like 100,000 mph and can conduct 1000s of Amps. ESD is just a way to simulate a small scale jolt - and if you read the standards you see ESD testing models are highly controlled - so much voltage, via such and such a capacitor and resistor - etc. And as someone else mentioned, the regular surge protectors you plug computers into, mainly use MOVs, and provide a modicum of protection from lightning surges on the power grid. Nothing will protect from a direct hit. The better surge protectors also have an RFI filter, which is usually a couple of coils and capacitors - these probably wouldn't do much to protect against lightning however. To protect data lines, transzorbs are one of the best devices - basically fast-response [ie, low-inductance] zener diodes. We used the ESD gun mentioned to ascertain the susceptibility of various lines leading to an embedded controller to transients, and tried several methods of protection. The transzorbs worked best, and in fact were invented for this purpose. Another thing we found, and as someone else mentioned, spark gaps work too. DUring testing, I noted that the ESD gun sparks would jump straight across the leads of radial-leaded caps, so besides the transzorbs, we also added spark gaps, as a direct pcb layout: |> <| with about a .1" gap. Cost nothing - but maybe not quite as effective as expensive vacuum-sealed gaps. ========= >Does lightning cause an ESD, EFT or low power EMP or all of those? > To answer part of this question, just turn on an AM radio during a thunderstorm. Lots of hi-frequency stuff - lightning strikes have very fast risetimes. regards, - Dan Michaels Oricom Technologies =================== -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu>

> >Yeah, I did something like this a while back - used the HV >ckt from an old TV set. As you say, this sorta thing is >**lethal** - and what makes it especially so is the amount of >current that can be transferred. One single 40M resistor is >not very safe, as the spark can usually jump it, and you >lose the current limiting ---> resulting in death. The resistor in question is six inches long, designed for high voltage applications -- http://www.SpamWhack.com A pre-emptive strike against spam Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 My transistor sings with unintended parasitic the smoke escapes By Jeff Stout -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestEraseME.....mitvma.mit.edu>

At 11:33 AM 8/1/00 -0400, Shawn Yates wrote: >I think the guns everyone in mentioning is what I am looking for. The power >supply side is not where the issue is, its the 100 ft plus communication >wire connecting the devices thats the problem. So, the induced charge from >a lightning strike in the vicinity is what i am testing against. I don't think the gun is what you want. Guns are more for testing against static discharges, typically from people. A near lightning hit, assuming you aren't coupled in directly by wire, is going to be a more magnetic event. For voltage induced into the comms wire, look for a powerline disturbance simulator. We had one of those. <1nS risetime 0-10kV pulses IIRC. Nasty! -- http://www.SpamWhack.com A pre-emptive strike against spam Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 My transistor sings with unintended parasitic the smoke escapes By Jeff Stout -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestmitvma.mit.edu>

That sounds like a dangerous workaround to using a resister meant for high voltage applications. -Adam Dan Michaels wrote: {Quote hidden}> One single 40M resistor is > not very safe, as the spark can usually jump it, and you > lose the current limiting ---> resulting in death. > > I used about a dozen resistors in series [forget the value, > but probably about 1-5M]. The spark would typically jump across > 1 or 2, but not the entire string. [this stuff is not for the > faint of heart]. > > - danM -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestEraseMEEraseMEmitvma.mit.edu>

> >Yes, that was a teenage hack job. I guess my point was Dave originally >mentioned using a "40M resistor", didn't mention the potential spark >jumping problem --> producing instant death. He has since mentioned >using a 6" long HV resistor. I just went through a lightning storm (between those emails) A near strike, a couple blocks away, gave the anticipated magnetic hit, and caused one of my USB serial adaptors to re-initialize. No high voltages involved locally. I'm a big fan of UPSs, and gas discharge tubes on all I/O. -- http://www.SpamWhack.com A pre-emptive strike against spam Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 My transistor sings with unintended parasitic the smoke escapes By Jeff Stout -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestTakeThisOuTspammitvma.mit.edu>

In message <EraseME39870DB2.CF262F81spamspamBeGoneubasics.com>, M. Adam Davis <RemoveMEadavisKILLspamUBASICS.COM> writes >That sounds like a dangerous workaround to using a resister meant for high >voltage applications. It's been used commercially for a great many years, it's very common practice to use resistors in series in high voltage circuits in TV sets. Someone commented about how 'lethal' the EHT circuit in a TV is, this isn't really very true - they are limited to around 1mA maximum current, much too low to be lethal (apart from falling over and breaking your neck). What is seriously dangerous is the HV circuitry in microwave ovens, 3KV at high current - almost certainly fatal!. I know of many people who have had shocks off the 24KV EHT used in TV's, and never heard of anyone being killed (I've had a fair few myself over the years). However, I've only ever heard of one person getting a shock from a microwave - he was lucky, the Paramedics happened to be already on the same street, they were there in a very short time, and managed to restart his heart (although I did hear he was never quite the same afterwards!). Anyway, it's obviously better to be safe than sorry, always respect the voltages and powers you are working with, if you never get a shock by being careful that's a huge bonus :-). -- Nigel. /--------------------------------------------------------------\ | Nigel Goodwin | Internet : nigelgSTOPspamspam_OUTlpilsley.co.uk | | Lower Pilsley | Web Page : http://www.lpilsley.co.uk | | Chesterfield | Official site for Shin Ki and New Spirit | | England | Ju Jitsu | \--------------------------------------------------------------/ -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestSTOPspamEraseMEmitvma.mit.edu>

> >It's been used commercially for a great many years, it's very common >practice to use resistors in series in high voltage circuits in TV sets. >Someone commented about how 'lethal' the EHT circuit in a TV is, this >isn't really very true - they are limited to around 1mA maximum current, >much too low to be lethal (apart from falling over and breaking your >neck). It's not the power supply that gets you, it's the pulse from discharging the CRT. The CRT acts as a capacitor, and a very good one. -- http://www.SpamWhack.com A pre-emptive strike against spam Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 My transistor sings with unintended parasitic the smoke escapes By Jeff Stout -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestspamBeGonemitvma.mit.edu>

Nigel Goodwin wrote: ......... >Someone commented about how 'lethal' the EHT circuit in a TV is, this >isn't really very true - they are limited to around 1mA maximum current, >much too low to be lethal (apart from falling over and breaking your >neck). ........ > >I know of many people who have had shocks off the 24KV EHT used in TV's, >and never heard of anyone being killed (I've had a fair few myself over ........ I'm not sure about that 1 mA business. I watched my father get zapped many times by color TV sets - he was a repairman - [back before the days of throwaway]. Usually the dynamics went - touch HV, arm flies backwards crazily due to muscles going into momentary tetanus, body careens backwards, oaths emitted from mouth, faint odor of burning flesh. Looking back, I suspect the muscle-tetanus/arm-flying-backward-out -of-harm's-way phase was normally critical to the heart-not-stopping phase. I always wondered about if you ever grabbed hold of that sucker really good. - danM -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestEraseMEmitvma.mit.edu>

DAve Van Horn wrote: ....... >I just went through a lightning storm (between those emails) A near >strike, a couple blocks away, gave the anticipated magnetic hit, and caused >one of my USB serial adaptors to re-initialize. No high voltages involved >locally. > >I'm a big fan of UPSs, and gas discharge tubes on all I/O. > BTW, you didn't happen to look inside the USB box to check what kind of transient protection is being used, did you? What do you think of transzorbs? On the embedded controller I've alluded to, we ended up using them on pretty much every single line into the box [in addition to the pcb-layout spark gaps] - albeit it was mainly to de-sensitive the box to local ESD application. We also ended up adding a crowbar, which is about the only way known to modern man of automatically re-initializing a latched-up controller chip. Prior to this, it was pretty neat to watch how zapping a 6 foot high box with a little ESD would instantly shutdown a $10,000 industrial refrigeration unit. - danM -- http://www.piclist.com hint: To leave the PICList @spam@piclist-unsubscribe-request@spam@spam_OUTmitvma.mit.edu>

> >BTW, you didn't happen to look inside the USB box to check >what kind of transient protection is being used, did you? Not yet.. :) >What do you think of transzorbs? Pretty good. I like neon lamps in a lot of applications, a bit slower perhaps, but dirt cheap, and quite effective. >On the embedded controller >I've alluded to, we ended up using them on pretty much >every single line into the box [in addition to the pcb-layout >spark gaps] - I've used those too.. Had one instance where the helpful board house shorted them out, somehow thinking they were accidentally open.. @$!#%!^%^ > albeit it was mainly to de-sensitive the box to >local ESD application. We also ended up adding a crowbar, which >is about the only way known to modern man of automatically >re-initializing a latched-up controller chip. Prior to this, >it was pretty neat to watch how zapping a 6 foot high box with >a little ESD would instantly shutdown a $10,000 industrial >refrigeration unit. The POS industry has a major show in Las Vegas, static capitol of the western hemisphere. I took our products there, in their little plastic cases, and the guy across from us was with Diebold, demoing their ATM machines (big, stainless steel cases, stainless steel keypads..). He's out there wetting the carpet with a spray bottle. Meanwhile, I'm wearing my special van-de-graff shoes, and doing a high speed shuffle across the carpeting, trying to build up the biggest charge I possibly can, and I can't hurt our equipment. (including direct discharges to cables and ports.) Later, I kind of forgot about the shoes, and killed a competitor's machine just by touching a button. Oops! -- Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestKILLspammitvma.mit.edu>

Shawn Yates wrote: ....... >Does lightning cause an ESD, EFT or low power EMP or all of those? > I just thought up another partial answer to this. We've had 3 people get killed by lightning on Colorado mountaintops in the past month. Aside from getting vaporized by a direct hit, the more usual method of death is from large ground currents that spread out in all directions from the point of impact. Last year an entire herd of 50 elk in the mtns were wiped out - no doubt because of the gnd currents. [BTW, the way to survive is to duck down, put your hands over your head (saves the ears), orient your body at right angles to the point of impact (good luck), try to balance on your tippy toes, and most importantly, insulate yourself from the gnd using your backpack]. The answer is probably lightning has many effects. As Dave mentioned, and as illustrated by my AM radio example, there is certainly an electromagnetic effect. This is possibly what your 100' long datalines experience. Also, once the lightning hits gnd, then you get large spreading surge currents - this is probably what your system experiences by virtue of being power by the mains. You need to protect against both, in general. - danM -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestspam_OUTmitvma.mit.edu>

Dave Van Horn wrote: ...... > [in addition to the pcb-layout >>spark gaps] - > >I've used those too.. Had one instance where the helpful board house >shorted them out, somehow thinking they were accidentally open.. @$!#%!^%^ > It's also fun if you accidentally cover the gaps up with the solder mask. [note, *I* did not do the pcb layout]. ================ > >Later, I kind of forgot about the shoes, and killed a competitor's machine >just by touching a button. >Oops! I notice you did indicate it was a "direct" competitor. - danM -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-request.....TakeThisOuTmitvma.mit.edu>

Dave Van Horn wrote: >> ......... >It's not the power supply that gets you, it's the pulse from discharging >the CRT. >The CRT acts as a capacitor, and a very good one. Yeah, I was thinking the same thing - except about the fat-little cap in the flyback ckt. The flyback transformer itself may limit the current pretty well, but if you get across that fat-little cap, you still may have a bad result. [note - this is the one still present after you remove the HV ckt from the TV, and start using it as a cheapo ESD zapper]. Just guessing: Ic=C[dv/dt] ~ .01uF [40,000/10usec] = 40 amp [I think caps were created for a special reason - to keep engineer's from getting too damn lazy in their work habits]. - danM -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestKILLspamspammitvma.mit.edu>