Post by thread:[PICLIST] Wimshurst machine (sold), Oz lightning t

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 -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

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? -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

>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 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics