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'[EE]:Lightning'
2000\07\31@143603 by Shawn Yates

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       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

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2000\07\31@145652 by James Paul

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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}

spam_OUTjimTakeThisOuTspamjpes.com

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2000\07\31@164857 by Shawn Yates

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Sure, send me what you have please.

-----Original Message-----
From: James Paul [.....jimKILLspamspam@spam@JPES.COM]
Sent: Monday, July 31, 2000 2:55 PM
To: PICLISTspamKILLspamMITVMA.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
>
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.....jimKILLspamspam.....jpes.com

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2000\07\31@171533 by Dan Michaels

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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
===================

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2000\07\31@173820 by David VanHorn

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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.





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2000\07\31@175058 by Ben Wirz

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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}

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}

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2000\07\31@184127 by Shawn Yates

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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}

2000\07\31@193102 by David VanHorn

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>
>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.


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2000\07\31@202337 by Plunkett, Dennis

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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}


'[EE]:Lightning'
2000\08\01@030933 by Michael Rigby-Jones
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{Quote hidden}

Is it FCC compliant? <g>

Mike

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2000\08\01@080906 by W. K. Brown

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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}

2000\08\01@082603 by Alan B. Pearce
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>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....

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2000\08\01@113032 by Shawn Yates

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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.

Thanks to everyone.

Shawn

{Original Message removed}

2000\08\01@114330 by Howard Cripe

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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.
> >

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2000\08\01@115809 by Dan Michaels

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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

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2000\08\01@121946 by Dan Michaels

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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
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2000\08\01@133816 by David VanHorn

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>
>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


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2000\08\01@134033 by David VanHorn

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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!

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2000\08\01@135100 by M. Adam Davis

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That sounds like a dangerous workaround to using a resister meant for high
voltage applications.

-Adam

Dan Michaels wrote:
{Quote hidden}

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2000\08\01@141511 by Dan Michaels

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Adam Davis wrote:
>That sounds like a dangerous workaround to using a resister meant for high
>voltage applications.
>

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.

- danM

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2000\08\01@143141 by David VanHorn

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>
>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.

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2000\08\01@143345 by Nigel Goodwin

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In message <EraseME39870DB2.CF262F81spamspamspamBeGoneubasics.com>, M. Adam Davis
<RemoveMEadavisKILLspamspamUBASICS.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 :-).
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2000\08\01@145420 by David VanHorn

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>
>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.
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2000\08\01@145429 by Dan Michaels

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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

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2000\08\01@145432 by Dan Michaels

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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

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2000\08\01@151100 by David VanHorn

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>
>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!



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2000\08\01@153201 by Dan Michaels

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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

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2000\08\01@153840 by Dan Michaels

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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

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2000\08\01@154858 by Dan Michaels

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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

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