Re: [neonixie-l] NIMO
I gave that idea a lot of thought, but I decided against it for 2 reasons: #1 It will waste a fair amount of energy. There were several methods I analyzed using the power sources I had available in the design, and this was the closest to a perfect solution. #2 Using the center-tapped transformer made the best sense because it simplified the bias circuit, and using AC resulted in "averaging" that circumvents brightness variation seen in VFDs with a DC filament supply. -- 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/76a1a8a3-152f-49d8-8a60-7937819d8f1ao%40googlegroups.com.
Re: [neonixie-l] NIMO
> My original intention was that I would monitor the anode-current for all 6 > tubes, and I could detect a partial filament burnout by checking for > lower-than-expected current. Software could isolate the failing tube, then > shut down the clock. Unfortunately there is a source of noise in the op-amp > summer circuit I use that gives me erratic current readings. Eventually I'll > figure out what's wrong. I would have used a current regulated supply for the filament (well, six of them in your case), which will also automatically give a nice soft start-up, and allow you to easily monitor the filament by monitoring its voltage. - 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 view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/E3F812D0-8217-4E2E-955B-DB2D635B4B74%40mac.com.
Re: [neonixie-l] NIMO
After some experimenting, I ended-up using 5.1 ohms for a single resistor. I could have used 2 resistors, one on each side, to maintain DC balance but instead I chose to use a single resistor so I could have my FPGA monitor the filament status, along with it's associated fuse and resistor. Each filament has it's own 250mA fuse for protection (this is a 6-tube NIMO clock). It wasn't necessary it was to go to that extreme, and it burned-up a lot of FPGA pins, but this is a project/experiment where I really wanted to go overboard with the instrumentation and self-checking. DC-balance really isn't necessary because everything averages-out over time, and I just adjust the DC offset (with a DAC under software control). Regarding the filament, it's actually 2 parallel-connected filaments inside the tube. So when 1 of them blows, only half of the digits will work. My original intention was that I would monitor the anode-current for all 6 tubes, and I could detect a partial filament burnout by checking for lower-than-expected current. Software could isolate the failing tube, then shut down the clock. Unfortunately there is a source of noise in the op-amp summer circuit I use that gives me erratic current readings. Eventually I'll figure out what's wrong. -- 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/80ce6285-b50a-40af-8554-2c1fe75de18bo%40googlegroups.com.
Re: [neonixie-l] NIMO
Well, I can answer my last question on my own, didn't think correctly there - of course you don't short these resistors as that would result in 2.5V across the heaters. The reason I asked was because I thought you perhaps had two sets of series resistors, one left in the circuit at all times and one that was shorted after some time. /Martin On Tuesday, 30 June 2020 23:25:32 UTC+2, Dekatron42 wrote: > > So you are using something like a 6.8 Ohm series resistor on each side of > the heater to get these figures? > > If you use a series resistor on each side, what effect does that result in > on the DC-bias, none or something that you have to adjust for? > > Do you short these resistors after some time so they are not affecting the > circuit, or do you leave them in there? > > /Martin > > On Tuesday, 30 June 2020 21:03:50 UTC+2, gregebert wrote: >> >> Be careful about the inrush current when energizing the filaments; the >> cold resistance is around 2.8 ohms, whereas hot is around 7 ohms. So, with >> a 1.1V supply, your surge-current will be about 400mA unless you use >> circuit tricks to lower it. >> >> I use a series resistor + fuse and drive from a 2.5V transformer; my peak >> current is around 250mA, and 180mA operating. >> > -- 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/b04c36e1-fab0-408c-bb77-c71eb5039ba9o%40googlegroups.com.
Re: [neonixie-l] NIMO
So you are using something like a 6.8 Ohm series resistor on each side of the heater to get these figures? If you use a series resistor on each side, what effect does that result in on the DC-bias, none or something that you have to adjust for? Do you short these resistors after some time so they are not affecting the circuit, or do you leave them in there? /Martin On Tuesday, 30 June 2020 21:03:50 UTC+2, gregebert wrote: > > Be careful about the inrush current when energizing the filaments; the > cold resistance is around 2.8 ohms, whereas hot is around 7 ohms. So, with > a 1.1V supply, your surge-current will be about 400mA unless you use > circuit tricks to lower it. > > I use a series resistor + fuse and drive from a 2.5V transformer; my peak > current is around 250mA, and 180mA operating. > -- 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/0c9c67ea-f4db-4606-b480-54aa93e7b252o%40googlegroups.com.
Re: [neonixie-l] NIMO
Be careful about the inrush current when energizing the filaments; the cold resistance is around 2.8 ohms, whereas hot is around 7 ohms. So, with a 1.1V supply, your surge-current will be about 400mA unless you use circuit tricks to lower it. I use a series resistor + fuse and drive from a 2.5V transformer; my peak current is around 250mA, and 180mA operating. -- 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/876362d4-30ef-42ed-b39d-9c59db3e018co%40googlegroups.com.
Re: [neonixie-l] NIMO
Yes, i agree with grebert. The filament driving was the most "dangerous", in terms of afraid, part for me. Not the high voltage. I do not want, in any case, to overload or destroy the filament due to too much current. The 1,1Vrms are crucial, because it affect the lifetime of the tube. Thats why I've choosen the royer type of pws and not a linear regulated power supply, which was my first idea. -- 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/1c8979a8-e34e-481b-abb2-b4e35c62a392o%40googlegroups.com.
Re: [neonixie-l] NIMO
No worries... NIMO tubes are not harmful in terms radiation (voltage is too low), and any toxicity of internal materials would be no-worse than a CFL bulb (I doubt NIMO tubes have mercury, but they do have phosphorus and other things). Even the high voltage (2kV) isn't harmful due to the low current (30uA per tube) as long as small capacitors are used. By far, the biggest risk is the handling of the tube itself, and making sure the circuit never exceeds the ratings of the tube, particularly the filament. -- 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/25f723ae-914b-4e53-8f55-839f3d757225o%40googlegroups.com.
Re: [neonixie-l] NIMO
Hi Martin, i did not work on the ghosting issue. I'm waiting for the pcb's. After that, i will start get rid of that problem. @paul: yes i know that video. It looks like that the ghosting issue is there, too. -- 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/93365f3e-69eb-46c0-aad2-eb7aa23519b1o%40googlegroups.com.
Re: [neonixie-l] NIMO
I assume you guys have also looked at this? https://www.youtube.com/watch?v=xmWg7CtN0Ac On Tuesday, June 30, 2020 at 10:21:27 AM UTC-4, Dekatron42 wrote: > > @jörg: if you fixed the ghosting you had on the digit, how did you do it? > > @gregebert: you mentioned some leaked from th "7" digit, what was the > cause of this? > > I am trying to get the courage to experiment with my NIMOs > > /Martin > -- 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/2310c1dc-74bf-437e-9ab4-9248820fd702o%40googlegroups.com.
Re: [neonixie-l] NIMO
@jörg: if you fixed the ghosting you had on the digit, how did you do it? @gregebert: you mentioned some leaked from th "7" digit, what was the cause of this? I am trying to get the courage to experiment with my NIMOs /Martin -- 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/175ca4f9-d3b8-42b4-a94c-88448aca818do%40googlegroups.com.
