Yet one more topic I neglected to address - voltage regulation. Probably most critical for the deflection circuits. The majority of examples I find on the web based on simple tube transformer based supplies don't appear to include any kind of regulation (I'd guess switched type supplies are regulated). But many of the examples of basic oscilloscope type gear implement zeners for the approx +300VDC anode / deflection supply.
On Tue, Oct 28, 2025 at 6:15 AM TomJ <[email protected]> wrote: > Forgot to mention - if anyone else is considering a crt clock project, > brand new Chinese 3RP1A tubes are available from US sellers on eBay (3 for > $85 shipped). But they are listed with the letter "I" instead of the > numeral "1" - the eBay search doesn't pick up on that, so they are easily > overlooked. I think these are the same ones that Sphere used to sell. > > On Tue, Oct 28, 2025 at 6:07 AM TomJ <[email protected]> wrote: > >> >> >> On Mon, Oct 27, 2025 at 4:31 PM Mac Doktor <[email protected]> >> wrote: >> >>> >>> Note that over at the GeigerCounters group talking about building >>> negative HV power supplies can get you banned. A couple of people found >>> that out the hard way after having been warned. The -900V supplies in >>> Geiger counters are grandfathered in, of course, and the currents are very >>> low. >>> >>> >>> >> Certainly, the voltages involved are no joke and can be lethal. CRT >> voltages typically are very low current as well, but I suspect still very >> dangerous. Though it seems a bit >> nanny-state' to ban legitimate scientific discussions - you can just as >> easily discover mortality working on your car or a home appliance. >> >> In any event, I also received a very informative email from the gentleman >> at Sgitheach... My understanding is that the crt tube doesn't really care >> - it comes down how you want to design your circuit. Having the high >> potential at the cathode makes the deflection circuit easier to implement >> because the voltages are lower. BUT, if you desire to incorporate some >> kind of intensity modulation or Z axis, you now have to manage that end >> with high voltages. The end result from a performance perspective will be >> the same. >> >> Thanks for the insight! >> > -- 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/CAArLthdWyGPOcwfqSukypXgCHOr2e3mBGwqTkK9w4ZXTN4ENtw%40mail.gmail.com.
