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'[PICLIST] Wimshurst machine (sold), Oz lightning t'
2000\08\10@180042 by Peter L. Peres

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Dennis Plunkett wrote:
>As I indicated some time back an ESD gun is not a pratical test.
>Some of the tests that are conducted require 20kA to be dumped into
>equipment, can ESD do that!

FYI a vaccum 'doorknob' capacitor or two in parallel charged to ~10-30 kV
by an ESD gun (takes minutes) (or ionizer PSU, which is what I use),
exceed 5 kA when arcing across 1/2". Measured with storage (analog) scope
and later with specialized integrator + very low probe R (10 mohms). Yes I
did get 50V on a differential probe on that. The arcing voltage was very
hard to determine. After frying a few (two) DVMs I resorted to an analog
one which survived the tortures and still works ;) I am not sure that I
want to do that testing again now. I had ringing in my ears for days
afterwards and probably some spark images printed on the retina too. The
spark gap was a M4 screw with a copper 'fingered' nut on the ground side,
and a piece of 4 mm brass tube, soldered shut and rounded at +. The screw
end was also rounded with a file and polished. I used about a foot length
of a broom handle for this, or rested it on 3 stacked kitchen cutting
boards (medium density PTFE, oven dried).

These experiments do Mr. Hertz great honor. Afaik he did this kind of
testing in his physics lab and managed to obtain sparks in the secondary
dipole at 3-5 meters from the transmitter ;) ;). Maybe he used a Wimshurst
machine too, although I understand that they are temperamental (they tend
to start with the wrong polarity given half a chance) ;) ;) (In fact I
think he used something like a Tesla generator or induction coil).

Peter

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2000\08\10@210539 by Dan Michaels

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face
Peter Peres wrote:
>Dennis Plunkett wrote:
>>As I indicated some time back an ESD gun is not a pratical test.
>>Some of the tests that are conducted require 20kA to be dumped into
>>equipment, can ESD do that!
>
>FYI a vaccum 'doorknob' capacitor or two in parallel charged to ~10-30 kV
>by an ESD gun (takes minutes) (or ionizer PSU, which is what I use),
>exceed 5 kA when arcing across 1/2". Measured with storage (analog) scope
>and later with specialized integrator + very low probe R (10 mohms). Yes I
>did get 50V on a differential probe on that. The arcing voltage was very
>hard to determine. After frying a few (two) DVMs I resorted to an analog
>one which survived the tortures and still works ;) I am not sure that I
>want to do that testing again now. I had ringing in my ears for days
.............
>

But more importantly, did your embedded system survive?

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2000\08\11@072018 by Peter L. Peres

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>did it survive

The reason I did all this was, that it did not, and I tried to reproduce
the conditions in the switchbox where it was dying.

So armed with my artificial lightning machine I started working and got it
to survive indefinitely at 30 cm in a metal box after ~20 hours and 4
versions. (I did not know about the conditions in the switchbox until it
was too late).

This was a data logger kind of thing that was designed to log peak
overload with time of occurence and a hours meter combined.

Peter

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