No problem; amazing what you can do with 500nm..... Since they actually are UV LEDs, you may want to tweak the software so they can be turned off after a few seconds if your clock is direct-drive. If it's multiplexed, you probably need the UV on continuously in the dark (would be very informative to run an experiment here to find out....).
On Monday, February 19, 2024 at 9:53:17 PM UTC-8 Jeff Walton wrote: > Hi Greg, > > The LEDs were 385nM, not 885nM. > > Clearly the LEDs were UV. I initially thought the 365nM would be more > effective but they were not. The 365nM parts might have also been less > desirable from a safety standpoint and were also quite a bit more > expensive. The 405nM UV LEDs are less expensive and more plentiful but > seem to have more visible light spill. > > I wish that I could edit the original post, but no such luck! > > Jeff > > -------- Original message -------- > From: gregebert <[email protected]> > Date: 2/19/24 10:56 PM (GMT-06:00) > To: neonixie-l <[email protected]> > Subject: Re: [neonixie-l] Helping Nixie Tubes Fire in a Darkened Room > > 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 * >> *------------------------------* >> >> >> [email protected] >> [email protected] >> (952) 943-2064 Home >> (612) 865-5560 Cell >> >> >> >> *From:* [email protected] <[email protected]> *On Behalf >> Of *Jeff Walton >> *Sent:* Wednesday, November 29, 2023 8:44 PM >> *To:* neonixie-l <[email protected]> >> *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 [email protected]. >> >> 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 [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/bb3b4ba6-8597-48c9-af56-c0a9e3de97c7n%40googlegroups.com > > <https://groups.google.com/d/msgid/neonixie-l/bb3b4ba6-8597-48c9-af56-c0a9e3de97c7n%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 [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/ea40fecb-d8b6-4550-a0a4-e60f6585289bn%40googlegroups.com.
