> On Oct 30, 2021, at 6:17 PM, Tom Harris <celephi...@gmail.com> wrote: > > Which is why you use a string of them in series for this sort of thing.
My old HV scope probe has a resistor in it that's several inches long. It's rated something like 40kV and several rings in front of the handle to prevent arc-over. Must be for checking the high tension in a TV set. I also have a small laser power supply that I bought as a kit at a hamfest around '93. The bleeder on it is almost as long. Like all laser PS kits I've seen the design is rather dodgy. The power transistor is only a TO-220 and the kit included a flimsy snap-on heat sink that gets too hot to touch in about fifteen seconds. I asked the seller about it and he said not to worry as the transistor was running within its heat spec. Right. When I can smell a transistor from across the room it's probably too hot. I retrofitted it with the most enormous vertical TO-220 heat sink I could find and even that got too hot to touch after a few minutes. Switching out the 0.5mW tube that came with the kit with a 0.25mW finally solved the problem. > With appropriate insulation, I saw glass tube used in a physics lab. You can always fill the tube with transformer oil. Preferably the kind that doesn't have PCBs in it. Terry Bowman, KA4HJH "The Mac Doctor" Q: Should car stereo speakers be pointed to the rear for more thrust or up for more traction? A. On long trips, the 20- to 30% improvement in gas mileage you might get with speakers pointing to the rear is certainly worthwhile. On the other hand, if you drive on snow or ice, the extra traction of speakers pointing upward gives you added control. Don Lancaster -- 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 neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/83B73C0A-0CBD-4726-B8E1-CF7EBBD10180%40gmail.com.
