Re: [neonixie-l] Constant current source design
Oh, I could tell you some stories. When we did some early ships of advanced workstations to universities, I had a bunch of complaints from Cambridge University that their optical mice were failing randomly. I phoned the lab tec to find out what was going on .. these mice used two colours of LED, and a reflective pad with a grid of lines on. So, he told me that one in particular was random, jerky, and sometimes the mouse pointer wouldn't move at all. I asked him for the serial number of the failing mouse (thinking was there a bad batch?) .. he said Hang on, just have to shut the blinds so I can read the number - sunlight is too strong ... (a long pause) ... oh, wait, it's working now. And that was a leading academic institution. Speaks to the difference between intelligence and common sense, I feel. I had another complaint from a customer somewhere in NY state that one of my workstations had a CRT screen where the image wobbled. Just the one. .. on a hunch I asked him where it was in the room. Next to a wall, he said. Can you move it away from the wall? Oh, look, it has stopped wobbling now. What's the other side of that wall? A huge transformer serving power to the building apparently. *sigh* -- 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 post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/83b7304e-4675-4046-867c-d87e43ae1fda%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Constant current source design
There is a very similar story about an early super computer developed at Control Data in the 70's. An AC outlet on the side of the machine was intended for engineering for debug instruments. But nightly, when the cleaning lady plugged in her vacuum cleaner, the machine would crash. It took days to figure it out. Terry On Thursday, April 20, 2017 at 2:34:21 AM UTC-5, rd2...@yahoo.com wrote: > > That story reminds me of one from work. Not Nixie-related but sorta funny > :) > > Years ago, work had an IBM System/360 ot /370 of some age; It started > having faults at random times, so they called in the tech. He opened the > system covers, tied in all the diagnostics tools - logic analyzer, etc, > but, zero faults happened over a couple days of his running those; So they > pulled them out & closed the system up. Next day a few faults happened, so > he was called back in, wired it up and ran it another week, no faults. He > pulled the test gear & closed it up, but it crashed before he even made it > to his car; He was called back in and of course once wired up, zero > errors... > > The light finally lit up on someone's brain in there (reports varied on > whose!) - That the system cover doors, when OPEN, would preclude any > errors, but when they were closed, errors would occur; So they looked at > the wiring harnesses and found the harness that was flexing when the doors > were closed, which had a nasty intermittent in there, that was only going > open circuit VERY rarely, if quite enough to be horribly ANNOYING. > > Systems Engineers types and so on, HATE intermittents, they're the bane of > their existence :P LOL And they're quite annoying to debug, sometimes you > can't figure out where the darned things are hiding at all. > > Mark > -- 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 post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/03b8a8e6-a5ba-4451-abe3-ba33a299f26d%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Constant current source design
That story reminds me of one from work. Not Nixie-related but sorta funny :) Years ago, work had an IBM System/360 ot /370 of some age; It started having faults at random times, so they called in the tech. He opened the system covers, tied in all the diagnostics tools - logic analyzer, etc, but, zero faults happened over a couple days of his running those; So they pulled them out & closed the system up. Next day a few faults happened, so he was called back in, wired it up and ran it another week, no faults. He pulled the test gear & closed it up, but it crashed before he even made it to his car; He was called back in and of course once wired up, zero errors... The light finally lit up on someone's brain in there (reports varied on whose!) - That the system cover doors, when OPEN, would preclude any errors, but when they were closed, errors would occur; So they looked at the wiring harnesses and found the harness that was flexing when the doors were closed, which had a nasty intermittent in there, that was only going open circuit VERY rarely, if quite enough to be horribly ANNOYING. Systems Engineers types and so on, HATE intermittents, they're the bane of their existence :P LOL And they're quite annoying to debug, sometimes you can't figure out where the darned things are hiding at all. Mark -- 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 post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/1036708814.5399457.1492673659575%40mail.yahoo.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Constant current source design
You need a few ions around in the Neon for the cascade to start. This can happen for a variety of reasons including cosmic rays, background radiation or doping of the gas mixture with something radioactive. There is at least one thread on here about radioactive nixies (which sent me off on a side quest that hasn't quite finished yet!). Apparently 5092's are dosed with Kr-85 and have a little radioactivity symbol on them. -- 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 post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/f4e51f3a-2924-481a-b75c-e11306aebe20%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Constant current source design
I told this story here to the previous generation of readers... In a facility where I worked for a few years back in the mid-1970s there was also a two-rack-cabinet trigger tube monster. Its task was to check the teletype data that was arriving over an HF radio network. When [parity] errors were detected the device issued a request for a re-send. The story goes that one Friday there was a fault and it was very intermittent. The guy working on it was tearing his hair out and went home late that night. It ran fine for the rest of the weekend. Monday morning came and the equipment room staff tidied up and closed the cabinet doors. Within hours the intermittent was back. It took a while but eventually the penny dropped. The room was lit with strip lighting [fluorescent tubes] banks that were seperately switched and also a couple of PAR 38 flood lamps had been mounted on the ceiling pointing into these cabinets because of the 'strange' construction and difficulty of working on it. The room temperature did vary quite a lot too surprisingly. Desert conditions outside with temp differentials of twenty-odd [degrees] C. They eventually noticed that the fault wasn't present when the cabinets were open and the bright lights were on. The particular trigger tubes became hard to get and the particular guys working on the equipment didn't manage to identify which tubes were the problem and wanted to use the 'shotgun' approach with the fault. [Longer story there :-)) ] Eventually they took the doors off and made sure that the internals were brightly illuminated! John K - Original Message - From: Tomasz Kowalczyk To: neonixie-l Sent: Thursday, April 20, 2017 7:52 AM Subject: Re: [neonixie-l] Constant current source design W dniu wtorek, 18 kwietnia 2017 15:46:38 UTC+2 użytkownik jrehwin napisał: - while testing it I found out that striking voltage of tubes is a max value - I've tested one Z567M and one LC-631, they both strike with voltages lower than their normal maintaing voltage! Yes, it's a maximum value, so people can design circuits that are guaranteed to strike even with a worst-case tube, under worst-case conditions (see below). I wonder if this low striking voltage is common among different tubes or does the striking voltage change with temperature. Temperature has a minimal effect on striking voltage. The big factor is something to start the ionization cascade. If the tube is exposed to light, photons will do the trick. Radiation of other forms will as well. Worst case is in absolute darkness. For some designs, striking speed also matters: the higher the voltage, the faster the tube will strike. For some designs this can matter. One workaround is to have a "primer" electrode, to provide a source of ions to start the tube. While nixies don't normally come with primer electrodes, you can use a decimal point as a primer, just hook it up via a very large resistance. This will reduce the striking voltage and time significantly in the dark. - John Wow. I didn't think much about how the ionization starts. I was quite surprised as after reading this I turned off all lights in my room and with 150V the same LC-631 didn't start - but as soon as I put some light on it, it indeed started glowing. Unfortunately I can't use any decimal point as a ignition starter for the simple reason - almost none of B13B socket tubes have a decimal point :) and I own mostly those tubes (ZM1040, Z566M, LC-631, Z560M). Thank you for sharing this information and making details of how nixies work more clear to me. Also thank you for sharing the idea of programming the boost converter to have a startup routine - this is so simple and yet I didn't think about it. Do you know if there is an effect of lowered striking voltage for some time after the tube is turned off? I'm curious if it is possible to add PWM dimming or even multiplexing with 145V power supply with 180V starting routine. As I tested my LC-631 it seems to light up properly in darkness after it was lighted once with my desk lamp - after that I can disconnect it, wait few seconds and reconnect and it works immidiately. I don't know if it is a rule or just a coincidence. -- 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 post to this group, send email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/aa645b68-5fa0-4212-8b9d-b75f69e6794f%40googlegroups.com. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving
Re: [neonixie-l] Constant current source design
W dniu wtorek, 18 kwietnia 2017 15:46:38 UTC+2 użytkownik jrehwin napisał: > > - while testing it I found out that striking voltage of tubes is a max > value - I've tested one Z567M and one LC-631, they both strike with > voltages lower than their normal maintaing voltage! > > > Yes, it's a maximum value, so people can design circuits that are > guaranteed to strike even with a worst-case tube, under worst-case > conditions (see below). > > I wonder if this low striking voltage is common among different tubes or > does the striking voltage change with temperature. > > > Temperature has a minimal effect on striking voltage. The big factor is > something to start the ionization cascade. If the tube is exposed to > light, photons will do the trick. Radiation of other forms will as well. > Worst case is in absolute darkness. For some designs, striking speed also > matters: the higher the voltage, the faster the tube will strike. For some > designs this can matter. > > One workaround is to have a "primer" electrode, to provide a source of > ions to start the tube. While nixies don't normally come with primer > electrodes, you can use a decimal point as a primer, just hook it up via a > very large resistance. This will reduce the striking voltage and time > significantly in the dark. > > - John > > Wow. I didn't think much about how the ionization starts. I was quite surprised as after reading this I turned off all lights in my room and with 150V the same LC-631 didn't start - but as soon as I put some light on it, it indeed started glowing. Unfortunately I can't use any decimal point as a ignition starter for the simple reason - almost none of B13B socket tubes have a decimal point :) and I own mostly those tubes (ZM1040, Z566M, LC-631, Z560M). Thank you for sharing this information and making details of how nixies work more clear to me. Also thank you for sharing the idea of programming the boost converter to have a startup routine - this is so simple and yet I didn't think about it. Do you know if there is an effect of lowered striking voltage for some time after the tube is turned off? I'm curious if it is possible to add PWM dimming or even multiplexing with 145V power supply with 180V starting routine. As I tested my LC-631 it seems to light up properly in darkness after it was lighted once with my desk lamp - after that I can disconnect it, wait few seconds and reconnect and it works immidiately. I don't know if it is a rule or just a coincidence. -- 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 post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/aa645b68-5fa0-4212-8b9d-b75f69e6794f%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Constant current source design
It's done in FPGA code (verilog). I created a crude A-to-D converter using a resistor tree into 4 FPGA pins. The resistors are ratioed to give the FPGA indication when the anode voltage is 140,160, 180, or 200V. From there, the FPGA adjusts the duty-cycle of the DC-DC converter to change the voltage. I also use a soft-start on the HV DC to minimize Ldi/dt effects on the wiring, give the HV filter cap (0.3uF) a chance to charge-up, and minimize current-spiking the battery (my naive assumption is chemical reactions in a battery are not instantaneous). -- 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 post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/52443de9-b7db-4a03-a196-a07d9f37171f%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Constant current source design
> My wristwatch uses a 'boost' approach to ionize the display above 180V for > 25msec, then throttles back between 140 to 160V after the display is stable. > The saved energy is significant. It's 3-1/2 digits, direct-drive, and uses > NPN current-regulators for each segment (24 total). Is that done in software, or what? It just occurred to me that you could add a parasitic multiplier "starting circuit" similar to the ones used in helium-neon laser power supplies to do this automatically*. However, another multiplier segment just might produce enough voltage to endanger other components (depends on what the AC drive voltage is, and the margins on the other components). * such lasers generally run on 1700V or so, but can require upwards of 10kV to start > My bench prototype has been running for over 2 years now on the original > charge to the battery (3.7V Li-ion, 1050mA-hr). I dont display the time more > than a few times per week, but the fact it's still operating is amusing. BTW, > the battery was not new, either. It was used for a few years in my cellphone > so it's capacity is diminished. That is both amusing and cool. - John -- 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 post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/86409E7F-0FDD-4873-90D9-BE9902118D71%40mac.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Constant current source design
My wristwatch uses a 'boost' approach to ionize the display above 180V for 25msec, then throttles back between 140 to 160V after the display is stable. The saved energy is significant. It's 3-1/2 digits, direct-drive, and uses NPN current-regulators for each segment (24 total). My bench prototype has been running for over 2 years now on the *original* charge to the battery (3.7V Li-ion, 1050mA-hr). I dont display the time more than a few times per week, but the fact it's still operating is amusing. BTW, the battery was not new, either. It was used for a few years in my cellphone so it's capacity is diminished. -- 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 post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/32ec81ec-fc3c-4387-a90e-376d346b2cc4%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
