885-890nm ? That's infrared. If the LEDs are always-on, then I'm glad you're using IR instead of UV because it's much less harmful (perhaps harmless ?) to materials and humans/pets, etc.
BTW, those are really interesting tubes. I dont think I've ever seen tubes with a solid/opaque anode. On Monday, February 19, 2024 at 5:19:12 PM UTC-8 Jeff Walton wrote: > I posted this a couple months ago regarding the MG-17G display tubes that > wouldn’t fire reliably in the dark. The final resolution for it was to > mount some 885-890nM UV LED’s under the tubes. A completely updated > display board with LEDs driven from a fixed supply and a transistor on an > LDR so that they LEDs only turn on in a darkened room. This 885nM > wavelength seemed to work better than the 865mM and was less visible than > the 905nM LEDs. I wasn’t trying for a visible underlighting effect on the > tubes, so they are being driven at about 2mA so that there is sufficient > light without excessive glow. > > > > The clock is a Richard Scales design and this is the only one (so far) > with the “keep alive” LEDs. The tubes do not have a keep alive cathode, so > this method works. Otherwise, any single segment or decimal point would > not fire reliably. Now the tubes light dependably. Thanks to Richard for > the new board and a lot of back and forth to get this working right! > > > > The original PCB: > > > > The new PCB: > > > > The display in operation: > > > > The case in Place with LEDs on: > > > > The finished clock: > > > > Once we got past the issues with dark operation, the clock performs very > well! > > > > Regards, > > > > > > > > *Jeff Walton * > *------------------------------* > > > jwalt...@gmail.com > jwalt...@msn.com > (952) 943-2064 Home > (612) 865-5560 Cell > > > > *From:* neoni...@googlegroups.com <neoni...@googlegroups.com> *On Behalf > Of *Jeff Walton > *Sent:* Wednesday, November 29, 2023 8:44 PM > *To:* neonixie-l <neoni...@googlegroups.com> > *Subject:* [neonixie-l] Helping Nixie Tubes Fire in a Darkened Room > > > > I've recently come across a situation where I have some tubes in a clock > that are being directly driven and are having trouble starting when the > room is darkened but light right up when a room light is turned on. These > particular tubes were probably intended for use in a calculator. They are > seven segment neon MG-17G tubes. Once the tubes have any of the segments > lit, there is really no issue with the performance. It's when the tubes go > completely dark if a space is used while scrolling a message or lighting a > dash on and off to emulate a colon. I'm wondering if others have found any > particular tricks to help convince tubes to light up. There is no > "baselighting" and the HV is ~172v. I'm considering increasing the HV by > 10-15v but don't want to over drive the tubes. Short of putting a > radioactive source in the vicinity, are there other things that anyone has > had any luck with? > > > > Jeff > > -- > > 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+...@googlegroups.com. > > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/d5713f02-ec1d-493d-b12f-644fb080ee71n%40googlegroups.com > > <https://groups.google.com/d/msgid/neonixie-l/d5713f02-ec1d-493d-b12f-644fb080ee71n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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/bb3b4ba6-8597-48c9-af56-c0a9e3de97c7n%40googlegroups.com.
