Well, Terry, that was very interesting. I just went out to the shop and measured the resistance of the secondary of my neon sign transformer to ground, and sure enough it was definitely non-infinite (about 50k from one side, and greater than the 2M maximum of my cheap garage DVM on the other). I personally was still using it safely, because I clamped one side of the secondary directly to the workpiece, and the other I held at the end of a 14" plastic rod - but still...
What do you mean by "shunt limited"? I always believed that the current limiting was by virtue of the inductive impedance of the many turns in the secondary - basically the same as a fluorescent lamp ballast. Is there some other mechanism at work? On Thursday, November 28, 2024 at 6:56:37 PM UTC-8 Mac Doktor wrote: > > On Nov 26, 2024, at 3:15 PM, Mark Moulding <[email protected]> wrote: > > Those transformers are dangerous as hell, because one side of them is > ground (plus nearly a full amp or so available current - 1 kW, right?) - > super easy to get a path through YOU to ground. I've done "fractal art" > (nothing to do with actual fractals, of course), but I used a neon sign > transformer - isolated, and only around 15 mA of current - and switched it > with a momentary foot pedal. It would still have been an exceedingly bad > day to get across it, but I probably would have survived. I was extremely > careful... > > > For those who aren't aware, neon sign transformers are current limited > using shunts. Also, the secondary is center tapped to ground so the > potential from one wire to ground is only half that of the full secondary. > Or something like that. 8D > > > Terry Bowman, KA4HJH > "The Mac Doctor" > > https://www.astarcloseup.com > > “...the book said something astonishing, a very big thought. The stars, it > said, were suns but very far away. The Sun was a star but close up.”—Carl > Sagan, "The Backbone Of Night", *Cosmos*, 1980 > > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion, visit https://groups.google.com/d/msgid/neonixie-l/ae755b37-4eaf-45ee-88e4-637fc5e1ce3an%40googlegroups.com.
