Re: [neonixie-l] Re: Multiplexing noise
I used direct-drive on my first nixie project only because my gut-instinct was to keep it as simple as possible; I've stuck with that ever since. Too many postings about 'noisy nixies', choosing the correct cathode-current, bleeding, flickering, RFI, etc. I've even seen scary-looking blue arcs between anodes in a panaplex. Even my wristwatch is direct-drive (lucky me, the SP-151 has separate pins for each cathode segment...) Since I dont sell anything, the extra cost for direct-drive isn't an issue for me. That said, I have an unusual 9-segment (not a typo; it has 2 more segments in the middle so you can display characters like T, W, etc) display that requires multiplexing, and I hope to make a clock out of it in the near future. Fingers crossed I wont have any weird problemsjust wish I could find a few more of these units for spares. -- 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/1a902863-3f11-44e9-a9fd-f9d507e5b420%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Re: For Steampunk Nixie Clock Fans..
Hello Nick, I can feel this wandering off Topic slight.. Again.. LOL What a wonderful use for a 5C/3023. I did mention earlier that I had a bit of a fondness for Vintage aircraft, I had a complete Vampire T11 in my possession a few years ago XD515 (long story) not the smallest things to house so I donated it to RAF Cosford where it resides in the sheds at the back awaiting re-assembly. Not come across the 'Resin' on the lighting panel, but I know a lot of planes of the era had UV lighting in the cockpit that illuminated all the dials as they had radium? paint inside that glowed very nicely under UV. It could possibly be used to switch on the UV lamps? It was certainly the case in my T11. Is that your Firefly? On Monday, 23 February 2015 13:26:04 UTC, Nick wrote: On Monday, 23 February 2015 12:34:56 UTC, Paul Parry wrote: The part used on Gemini was a MK IB Directional Gyro as fitted to the Spitfire / Lancaster / Mosquito and most of the other planes of the era. They are abundant and you can get them on eBay for a couple of pounds, I used a scrapped one so there was no chance it would ever go up in the air again anyway Hi Paul, I, too, have a rather eclectic collection of ephemera... My workshop lights are controlled by an MOD 5C/3023 switchbox as used in Lancasters, Mosquitos, FIrefly Vs etc. - the MOD liked to use the same kit in multiple aircraft as it made store-keeping/spares easier to manage. Enclosed is an image of my 5C/3023 which I acquired NIB for just a few pounds, and a photo of the inside of the cockpit of a Firefly V undergoing restoration, showing the same model box (look closely!). EDIT: The RESIN switch controlled lights for a type of IFF system - there is much discussion, even today, on the exact nature of this, most choosing to believe that it was IR rather than visible-light based... Cheers Nick -- 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/7561963b-2aa8-4dc1-b3c5-4a9c6c30b0c1%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Re: For Steampunk Nixie Clock Fans..
On Tuesday, 24 February 2015 08:18:16 UTC, Paul Parry wrote: I can feel this wandering off Topic slight.. Again.. LOL It doesn't matter in this case. Believe me :) What a wonderful use for a 5C/3023. I did mention earlier that I had a bit of a fondness for Vintage aircraft, I had a complete Vampire T11 in my possession a few years ago XD515 (long story) not the smallest things to house so I donated it to RAF Cosford where it resides in the sheds at the back awaiting re-assembly. Not come across the 'Resin' on the lighting panel, but I know a lot of planes of the era had UV lighting in the cockpit that illuminated all the dials as they had radium? paint inside that glowed very nicely under UV. It could possibly be used to switch on the UV lamps? It was certainly the case in my T11. I've looked at some photos of XD515 - http://flickrhivemind.net/Tags/xd515 - it was really in poor shape - do you think that it'll ever fly again or will it be a static display? A major task if ever there was one. Top marks for stopping it rotting completely - certainly a long-term project ! Is that your Firefly? Regrettably (or maybe, thankfully) not - it was from another forum (Britmodeller) where we were discussing the true nature of RESIN - lot of argument about it as it was classified and seems to have changed its nature during its life. It was definitely IFF - not cockpit - the real question was was it just very dim/near-IR red lights or true IR - no-one seems to know for sure - some speculation too that is relied on other aircraft having a Tabby system on board... Cheers Nick -- 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/241170b1-a18c-450e-a228-9773e334b07b%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
[neonixie-l] Re: Russian 100x100 array
Those have been on ebay for a good while from the same seller, I was tempted a while ago but they are just too high a $ for my taste. The displays panels themselves are, if i recall from reading somewhere, a nightmare to drive as they use glow transfer to scan in data, so essentially gas based multiplexing. Those for 250 do look like they come with some soviet era wizardry in the box and he states are parallel 8 bit interfaces (LPT port...). I think I actually looked around at the time and discovered they were used on soviet CNC machines - I even found a Russian companies website offering LCD replacements for them. - Alex On Monday, 23 February 2015 13:36:45 UTC, Mike Mitchell wrote: Has anyone done anything with the Russian IMG-1 100x100 neon array? I've seen a few ebay postings http://www.ebay.com/itm/Rarest-NOS-NIB-NIXIE-MATRIX-screen-100x100-1-Z568M/321346505250 and http://www.ebay.com/itm/Rarest-NIXIE-MATRIX-screen-100x100-1-Z568M-tube-vfd-IN-18/321356330231 It looks interesting... -- 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/d2502193-8e21-4471-9785-03991350bb79%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Re: Multiplexing noise
Hi Yall, I've attached a picture of the display pcb layout and a pdf of the schematic for it. The cathode drivers are just the MPSA42 with a 100K ohm base transistor and the collector is tied directly to the cathode and the emitter is tied to ground. -joe On Mon, Feb 23, 2015 at 10:58 AM, gregebert gregeb...@hotmail.com wrote: I will try the biasing. would biasing both sides help? This would be sort of like terminating the lines. No need to worry about termination at this frequency, as in reflected waves, unless your PCB traces are several feet long... I did check the datasheets for the MPSA42/MPSA92 and they are a good choice because they have low leakage and high Vceo. Therefore *driver* leakage is not your problem; can you post a schematic of the driver predriver circuits ? It could be the predriver. It's possible the device driving your PNP anode driver is leaky, causing the PNP to turn-on slightly. Are you using a NPN predriver -- PNP driver arrangement ? If so, your NPN device could be leaking 0.1uA and your PNP will conduct beta times this. This is easy to fix with a resistor across the PNP's base/emitter to shunt-away the predriver leakage. It's also possible there is noise entering the predriver; this is where a scope will help. If you dont have a scope, then proceed with debugging he predriver. -- 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/6c5852ba-b890-4d1d-b20f-0a4c2ab78324%40googlegroups.com https://groups.google.com/d/msgid/neonixie-l/6c5852ba-b890-4d1d-b20f-0a4c2ab78324%40googlegroups.com?utm_medium=emailutm_source=footer . 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 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/CAE%2BVk6OWn90OEMi8ZxbfmNjM5TrfVRqhsF1A6D2%3DgeUcVeFHqA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout. display_schem.pdf Description: Adobe PDF document
Re: [neonixie-l] Re: Multiplexing noise
Joe -- the anode driver I borrowed from the open-source clock looks slightly different than yours. It uses the same transistors, but the MPSA92 has 100K directly across the BE junction, and a 470K between the MPSA42 collector and the MPSA92 base. In other words, imagine moving your R22 to the left of R21, and making R21 470K. (Temp 10 tube) Also, mine has a 33K from the driver to the base of the MPSA42, as opposed to your 100K. A little stiffer drive. I'm not saying either one is better -- just pointing out a difference. I haven't built this circuit yet, so it may need tweaking. I do think Niek has an astute observation regarding coupling -- I went to great pains in my layout to keep the low V drive circuit lines short and far away from the high V switching noise. Put my driver pairs right next to the decoder, and the lines from the connector to the decoder are as far from anything else as possible. Observing what flickers on and what other lines are switching at the time should point you right to the crosstalk source. Terry S. On Tuesday, February 24, 2015 at 6:15:37 AM UTC-6, joenixie wrote: Hi Yall, I've attached a picture of the display pcb layout and a pdf of the schematic for it. The cathode drivers are just the MPSA42 with a 100K ohm base transistor and the collector is tied directly to the cathode and the emitter is tied to ground. -joe On Mon, Feb 23, 2015 at 10:58 AM, gregebert greg...@hotmail.com javascript: wrote: I will try the biasing. would biasing both sides help? This would be sort of like terminating the lines. No need to worry about termination at this frequency, as in reflected waves, unless your PCB traces are several feet long... I did check the datasheets for the MPSA42/MPSA92 and they are a good choice because they have low leakage and high Vceo. Therefore *driver* leakage is not your problem; can you post a schematic of the driver predriver circuits ? It could be the predriver. It's possible the device driving your PNP anode driver is leaky, causing the PNP to turn-on slightly. Are you using a NPN predriver -- PNP driver arrangement ? If so, your NPN device could be leaking 0.1uA and your PNP will conduct beta times this. This is easy to fix with a resistor across the PNP's base/emitter to shunt-away the predriver leakage. It's also possible there is noise entering the predriver; this is where a scope will help. If you dont have a scope, then proceed with debugging he predriver. -- 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 javascript:. To post to this group, send email to neoni...@googlegroups.com javascript:. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/6c5852ba-b890-4d1d-b20f-0a4c2ab78324%40googlegroups.com https://groups.google.com/d/msgid/neonixie-l/6c5852ba-b890-4d1d-b20f-0a4c2ab78324%40googlegroups.com?utm_medium=emailutm_source=footer . 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 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/b1588d4e-55f7-4d6d-b3ff-c399857d684f%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Re: Multiplexing noise
Does the issue happen more to certain tubes/digits than to others? If so, it could have something to do with the layout of the traces: i'd be especially worried about long runs of high voltage lines parallel to the lines switching the transistors. E.g., in your PCB, the trace at the very bottom (originating out of M at the header) is a low voltage line that controls the anode switch transistors, and if you follow it up, it runs parallel to some high voltage lines. The high voltage line's fast switching could induce a smaller voltage spike at the base of that transistor, which could then turn it on. If this is the cause, it probably would show up more to certain digits/tubes than others. If it's the same for all, then there might be some problem with the program controlling it: e.g. you need to make sure to wait a small while after turning off one anode, then switch the cathodes, then turn on the next anode. Are you doing that? On Tuesday, February 24, 2015 at 1:15:37 PM UTC+1, joenixie wrote: Hi Yall, I've attached a picture of the display pcb layout and a pdf of the schematic for it. The cathode drivers are just the MPSA42 with a 100K ohm base transistor and the collector is tied directly to the cathode and the emitter is tied to ground. -joe On Mon, Feb 23, 2015 at 10:58 AM, gregebert greg...@hotmail.com javascript: wrote: I will try the biasing. would biasing both sides help? This would be sort of like terminating the lines. No need to worry about termination at this frequency, as in reflected waves, unless your PCB traces are several feet long... I did check the datasheets for the MPSA42/MPSA92 and they are a good choice because they have low leakage and high Vceo. Therefore *driver* leakage is not your problem; can you post a schematic of the driver predriver circuits ? It could be the predriver. It's possible the device driving your PNP anode driver is leaky, causing the PNP to turn-on slightly. Are you using a NPN predriver -- PNP driver arrangement ? If so, your NPN device could be leaking 0.1uA and your PNP will conduct beta times this. This is easy to fix with a resistor across the PNP's base/emitter to shunt-away the predriver leakage. It's also possible there is noise entering the predriver; this is where a scope will help. If you dont have a scope, then proceed with debugging he predriver. -- 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 javascript:. To post to this group, send email to neoni...@googlegroups.com javascript:. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/6c5852ba-b890-4d1d-b20f-0a4c2ab78324%40googlegroups.com https://groups.google.com/d/msgid/neonixie-l/6c5852ba-b890-4d1d-b20f-0a4c2ab78324%40googlegroups.com?utm_medium=emailutm_source=footer . 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 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/31f85a50-6d1e-4c4e-84c9-a064f2235db2%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Re: Multiplexing noise
Greg, I concur that these are fine things to do. I adjsuted my base-emitter resistor so that it would have about 0.3V across it if the base were disconencted form the circuit and the driving signal was on. Also, short wires from the driver to the tubes are helpful to reducing crosstalk. I made multiplexed clocks with direct PCB traces from tube to tube under the sockets, and did the timing things you mentioned. Most importantly, ensure some dead time (~100 usec) between turning off the anode and switching the cathode driver to the next digit's value. That's where I ran into trouble. On 2/24/2015 10:12 AM, gregebert wrote: Before you start hacking-up your PCB, can you try adjusting the timing of your anode drivers so there is some 'dead-time', say 50-100usec, after 1 anode is turned off, and the next one is turned on ? Also, if you can turn off all cathode drivers during the dead-time, that might help. This will ensure the tube is no longer ionized, and that should either reduce the unwanted glow or make it more difficult to re-ionize from leakage. And to be safe, dont turn off the anode cathodes at exactly the same time (stagger by ~1usec); otherwise you could create a di/dt problem from the stray inductance of the wiring. Now, if that doesn't work, next thing to try is a true base-emitter resistor, for example, moving the connection of R22 to the other side of R21 (see Terry's note). I dont think the resistor values are critical as long as they are at least 100K and they are 1/4 watt (or larger). You dont want them to overheat P=Vcc^2/R, so with Vcc=160V, R=100K, a 1/4W resistor is at the limit. If your local Radio Shack store hasn't shut the doors yet, grab some resistors. (I just got some stuff last night at a 95% discount) -- 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/54ECC11C.9080509%40dakotacom.net. For more options, visit https://groups.google.com/d/optout.
[neonixie-l] Re: Russian 100x100 array
On Tuesday, February 24, 2015 at 5:40:53 AM UTC-5, Alex wrote: Those have been on ebay for a good while from the same seller, I was tempted a while ago but they are just too high a $ for my taste. The displays panels themselves are, if i recall from reading somewhere, a nightmare to drive as they use glow transfer to scan in data, so essentially gas based multiplexing. Those for 250 do look like they come with some soviet era wizardry in the box and he states are parallel 8 bit interfaces (LPT port...). I think I actually looked around at the time and discovered they were used on soviet CNC machines - I even found a Russian companies website offering LCD replacements for them. I have a 512x512 VFD version in my collection. It is either a prototype or a part that failed testing, since there are no printed markings on it, just a number of comments like Dud scratched into the glass on the back (in Cyrillic). I was unable to get it to do anything at all, unlike the submarine one I posted about earlier. I guess it is just blue-green, though it is possible it is multi-color or RGB. Here are some pictures: http://www.tmk.com/transient/6F5S8652-s.jpg http://www.tmk.com/transient/6F5S8654-s.jpg -- 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/d3d1bb0b-9d39-4bb2-904e-27c2c5a8e5de%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Re: Multiplexing noise
Hi Yall, Okay, I scoped the board and I have almost 500us of total dead time between digits. This was measured on the digital outputs from the CPU. My code is written in a way that I turn off all of the segment and digit signals one at a time in a for loop so they are not all triggering at once. They are turned on in a like manner. I do not know the time between these, but the app know's nothing about the actual port and bit that is being turned on or off so I assume the time is in the 1us ball park if not more. I am using a 16MHZ ATMega328. As for direct drive, I am multiplexing because of a lack of pins and board space. I wanted a nice small board as well as through hole parts because I want to sell this as a kit. I just don't have room for a couple of more DIPS. I like the idea of the moving the resistors, I will try this. I will also spread my segment lines out going between the 4 digits up top and the 2 digits below. I am still contemplating the ground plains they are easy to do. I will have to ask a couple of people at work about the issue of them possibly increasing the coupling between the lines. Biasing the lines is another idea I will try as well.I can do most of these before the next board spin. Depending on how the other things I try go, I will then decide on the plains. -joe On Tue, Feb 24, 2015 at 2:28 PM, gregebert gregeb...@hotmail.com wrote: I used direct-drive on my first nixie project only because my gut-instinct was to keep it as simple as possible; I've stuck with that ever since. Too many postings about 'noisy nixies', choosing the correct cathode-current, bleeding, flickering, RFI, etc. I've even seen scary-looking blue arcs between anodes in a panaplex. Even my wristwatch is direct-drive (lucky me, the SP-151 has separate pins for each cathode segment...) Since I dont sell anything, the extra cost for direct-drive isn't an issue for me. That said, I have an unusual 9-segment (not a typo; it has 2 more segments in the middle so you can display characters like T, W, etc) display that requires multiplexing, and I hope to make a clock out of it in the near future. Fingers crossed I wont have any weird problemsjust wish I could find a few more of these units for spares. -- 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/1a902863-3f11-44e9-a9fd-f9d507e5b420%40googlegroups.com https://groups.google.com/d/msgid/neonixie-l/1a902863-3f11-44e9-a9fd-f9d507e5b420%40googlegroups.com?utm_medium=emailutm_source=footer . 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 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/CAE%2BVk6O3%2B5X_or%3DePCz%3DD_dXF27G52F1%2BRHO9TZtWt8NJ7hx_A%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
Re: [neonixie-l] Re: Multiplexing noise
Greg -- regarding the resistor size and power dissipation, if there are 6 digits (7 in this case with the neons), can't you figure the resistor duty cycle is 1/6th, and therefore smaller wattage resistors can be used? The average dissipation is more like .043 watts, by my back-of-the-napkin math. I realize the instantaneous dissipation is .25 watts, but resistors do have some thermal mass If I'm wrong here please correct me. I know I've worked on a similar problem before and I recall the answer was not so obvious. Terry On Tuesday, February 24, 2015 at 11:12:19 AM UTC-6, gregebert wrote: I think this is the problem: The base-emitter of the PNP is not shunted with a resistor (see note from Terry). The purpose of the base-emitter resistor is to provide a path for the leakage-current of the NPN predriver. With the schematic as shown, roughly half of the NPN's leakage current goes thru the base of the PNP. That current is them multiplied by beta, which I think was around 130 from the datasheet. It's not a lot of current, but it could certainly contribute to unwanted glowing. Before you start hacking-up your PCB, can you try adjusting the timing of your anode drivers so there is some 'dead-time', say 50-100usec, after 1 anode is turned off, and the next one is turned on ? Also, if you can turn off all cathode drivers during the dead-time, that might help. This will ensure the tube is no longer ionized, and that should either reduce the unwanted glow or make it more difficult to re-ionize from leakage. And to be safe, dont turn off the anode cathodes at exactly the same time (stagger by ~1usec); otherwise you could create a di/dt problem from the stray inductance of the wiring. Now, if that doesn't work, next thing to try is a true base-emitter resistor, for example, moving the connection of R22 to the other side of R21 (see Terry's note). I dont think the resistor values are critical as long as they are at least 100K and they are 1/4 watt (or larger). You dont want them to overheat P=Vcc^2/R, so with Vcc=160V, R=100K, a 1/4W resistor is at the limit. If your local Radio Shack store hasn't shut the doors yet, grab some resistors. (I just got some stuff last night at a 95% discount) -- 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/5ec88575-ab0c-4a83-9970-e5d7e10a90ae%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.