Hi in the previous mail bag video Robert Bruce sent in eight of these very nice Russian Nixie tubes and I love Nixie tubes. They're fantastic. Look, I've got them all lit up here. they're all working and I mentioned in the mailbag I might do a project with it.

Well, let's give it a burl and these are the Russian B model actually has the decimal point in here so we can have an eight digit counter with decimal point anywhere. This is going to be great. And Robert Kindly sent in the original Russian data sheet for this thing because I don't think there's any English data sheets available though. it could be wrong.

Um, this is basically the sorry I can't pronounce these in Russian but they generally known as the I N Twelve series Nixie tube. In this case, there's an A and a B model. You can see we've got the B model there. so the B model actually has pin twelve connected here, which is the decimal point that we saw before and these come in different types.

You might have seen the vertical ones that look like a tubes, you know, old-fashioned tubes with the pins all in the bottom. I Much prefer these ones. These are much nicer because you mount these directly on a PCB Like that and be mounted depends whether or not you want right angle. the other is good for right angle.

These are good for the application that I've got in mind for this thing which you'll see in a future video. I Won't tell you what it is yet, but basically we're going to have an eight digit counter display so let's take a close-up view of this if you haven't seen one before. We got our nipple on the bottom. Love the nipple and that keeps the vacuum inside these things.

These things are vacuum sealed so if you're making a piece of be cut out of course you can't just snap that off. Just don't come along with your side cutters and break it off. You got to drill a hole in and have that sitting inside your board. and what it basically is is a cold cathode display because there's no heater in this thing.

I'm like a valve so it doesn't work by way of the thermionic emission like our valves do and you can see that there's various levels inside there. They're all separated with these ceramic spaces in there like that and each one is a metal digit. You can see all the different digits so it's got all the different numbers in there. It's got you know, a 0 through to 9 a plus the decimal point as well.

So and they're all wired and you can see them going in there like that and they're just a metal outline of the digit that you want to slide and you can see a metal mesh in here like this in the front that is actually the anode. you apply your positive voltage to that you apply a negative voltage to any one of the other digit cathode plates in there and they'll start to glow if you're given enough voltage and current. And the way they glow is, They're basically our neon type lamps. You can think of them as that the gas in there is usually aren't mostly neon, but I have some mercury and possibly some argon as well in there and basically the cathode ie.

the digit that you're displaying when you apply a potential between the anode grid and that the actual cathode digit will get a nice glow around them. in this case, a beautiful orange that you saw before and I Hook it up to my high voltage power supply through a dropper resistor and you can see we've got the digit 8 lit up there and it's just one digit. So unlike a 7 segment display, it's not made up of segments. You've just got one segment shaped like the number 8.

and in this case here, we've got the number 2 and you can see that in there even though if you have a look in the side, number 2 is all the way back there. so that digit is all the way back, there's got all those digits in front of it, but you can still see it because it's basically glowing and you can see the glow around the other digits and through the mesh. If we take a look at the data sheet, please forgive my Russian but you don't need to know. Russian I Usually it's like fairly obvious because the numbers and units a pretty universal.

We're talking 170 volts here. this would be a nominal voltage two point five milliamps could be a nominal current or could be a maximum current not entirely sure. And then or point three milliamps here, would that would be the minimum our sustaining current to keep the thing on once you've turned it on. And that's all we really need to know.

They've got a few more down here. This 200 here is probably the absolute maximum voltage 120 to 170. That would be the sustaining voltage range there, and to 23.5 or maybe that's the maybe that's the maximum with nought point Seven average. Let's try and translate, and we mostly got that right.

By the looks of it, our using Google Translate here. no more than a hundred and seventy indications for current figures. Oh yeah, at the hundred degrees that we had there, that was the viewing angle: 120 170 Sustained discharge. There you go.

They actually got the word sustained in there. Two to three point, five, four digits for the decimal point. no more than 0.7 operating current average. So the digits are higher than the decimal point.

So if you're going to use the decimal point, you actually want to use that at a lower current, presumably. But that's all you need to know if. voltage and current. By the way, it's real easy to find.

Pin One. it's the white One, there. There you go. Dead giveaway.

Okay, I'll show you what I've got set up here. I've got my high voltage power supply set to 170 volts here just measuring the current and I've got my deck a resistance box here so that we can adjust the current of the dropper resistor effectively. Kurz. In the final design, we're going to need a dropper resistor.

and I've got a 20k resistor in there. One Point Six Seven Milliamps. It works just fine and it switches on just fine. There will be slight discrepancies of course, between different tubes, and I've got fixed exposure on the camera, so you'll be able to see the absolute change in the brightness there.

So one Point Six Seven Milliamps, let's actually dial that you can see back to 10k. So Two Point Seven Five Milliamps is a difference there. But let's work in. Let's go up to 120 k.

They're here 100 K There you go and it's still on. It's still on at Point Four Milliamps, but will it start up at that? So I'll switch it off. And yep, it still starts up at that. But let's go to say 200.

K Alright, still on to point Three that was below the datasheet value. Wasn't it? Point Two. Now it's still just on, so it's holding in there. but I don't suspect it will start up.

Ah no, we're lucky. Whoa, it's a lucky day. Go buy a lotto ticket. 0.4 milliamps.

Let's actually dial up that voltage. We can see if we go up to 200 volts, it gets brighter. If we go down 160, it's still sustaining that you might be able to see Actually, not all of it. Only partial part of that digit is actually glowing.

So yeah. I don't think that one's going to start up. And of course it makes a fool out of me, doesn't it? dammit? But let's go back to our seven digits here. I won't bother wiring that one back in and I've got a hundred and forty volts with 10k in there.

will it start up? and I basically only got the one dropper as this stuff for all of them, so you wouldn't do that in practice. But let's see if any of them start up. Ah, two of them, two of them got there and sometimes you actually see them. Come on later.

But let's wind our voltage up there. There you go. Our decimal point came on. Another digit came on as we go up.

so as I said, there's going to be slight discrepancies between those so, but let's drop it back down to 10k. 12 milliamps for all of them, that's pretty good. That's still within ballpark and they're all on. no worries whatsoever.

so we can turn that voltage down and we're still sustaining at or adjust. at 130 volts, really drops between 130 140 and then boom, it's off and there we go. It doesn't switch immediately all back on, so there's some threshold there that some of them are not meeting. They just slight discrepancies between the tubes, so that's cool.

Now we can design our circuit. Oh Drive in these puppies! Let's go! The first thing we're going to need is a high voltage power supply and Robert was kind enough to send in this little liar kit which I linking it down below and there's tons of these on various websites and eBay you can just buy Nick's each a high voltage Nixie Tube Driver Kids: most of them are like 9 to 12 volts input. Oh, what's going to pale this whole thing by 5 volts? But yeah, I Did you know I don't want to go roll my own high voltage power supplier just I Just want to get this thing done. So I've got this in hand I'm going to use.

This is a 12 volt input to a selectable voltage output will do 170 volts. It'll do out 5 watts for this particular one and that's 29 in milliamps capability at 170 volts. More than nuff to drive our eight digits here. If we only need you know, a couple of millions each.

No worries. The good thing about that is this just got a header on there. We can balm it, solder that directly. just you know, flat down onto our board.

No worries, could mount it vertically. but in my case, I'm going to mount it horizontally like that, so no worries, that'll work A treat. There we go. A bit of a goof on the layout of the cap and the inductor there.

The spacing on that I'll get a vertical pin header for that. Know that transistor is not missing. it's actually there. That's an IRF to I RDF are two twenty in the four pin dip package there, so no worries I know height wise, it's okay.

Maybe I could have been a couple of the parts over to get a lower height profile, but it should be okay for my purpose. And just a little tip. With our pin headers like this, you can put them in a little breadboard just to hold them in place to stop and wiggle and around. if you haven't done the whole size thing to make them press fit in there like this one hasn't so that'll work a treat.

And we feed 12 volts in and she works a treat. Almost bang on is a 680 ohm external resistor. No touchy 170 volts and that sets your array output voltage. So yeah, Beauty! But I know you're thinking will it power an array of nixies I've only got seven, haven't got eight but a near enough and bingo there we go.

It's true enough. 5.6 watts or 24 millionths. Now let's have a look at Dave care for a minute I will get out 170 volt her and I would power supply by experiment around about 22. K should do it for a single display and then for multiple displays along here.

then you would have a separate resistor going up like that. you'd have another 22 K Like that and because only one segment one. it's not a seven segment display, only one digit is on at any one time. You don't have to worry about sharing current through the different segments like you would if a you had a traditional seven segment display here, power through a single resistor, a single dropper resistor, and the other difference between drive and a traditional seven segment display is it's in the name seven segments.

you would have seven that drive lines coming in like this for the seven different segments you display. but because this is a digit based display, want to do zero to nine? We need ten separate lines or eleven if we want one for the decimal point as well. So that rules out our driver chip being your traditional BCD to seven-segment display driver because this is not a seven segment display. so he basically want like a latched shift register type thing coming in so that you know we've got a clock line coming in here like this and then a latch line coming in as well.

and then it shifts the digits because you don't want all of your outputs to I change like in sequence. As you shift the data through like this, you don't want to see that. so you want to have an internal light. So you clock it in and clock the data in that you want to display and then hit the latch strobe, the latch light and that'll transfer the data, boom all over and display the digit you want.

But of course the problem is 170 volts up here. and that means that this chip has to have 170 volts say around it to 200 volt capability. It's got to be a high voltage output driver. and of course it can't be a totem of poor output.

It's got to be a open collector output like that so or an open drain if it's a MOSFET whatever. So we need individual high voltage driver transistors drive in each one of these digit lines. If we got ten of them times eight digits. we've got 80 drive lines at least.

But if we include decimal points, we've got 88 Love 88. We're gonna see some serious now. Of course You should be saying are Dave You can multiplex the things you only need the one driver chip and then all the lines would be common like this. And then we can install a transistor up on the high side here to drive each one and you can multiplex it.

And yet, no worries, you can multiplex Nixie yard displays like this. They're fast enough to handle it. Now That would work a treat except for the fact that your driver chip That drives the base of this puppy also has to be a high voltage output driver. So you need another high voltage transistor here NPN to actually our drive this high voltage transistor.

So if you did that, it still need a two transistor solution for each of your eight segments. So yeah, I could multiplex this display, but you're going to have higher peak currents. it's going to be dimmer. it's a bit of an unknown, it's around.

and I yeah I don't think I'll do it I think I'll just go for a direct-drive solution. So I need like a huge number of driver chippies like this are infected ly if I could find one that had ten outputs one to drive each individual display like this. and there is an old 7400 series TTL chip that's designed with high voltage open collector applets designed for driving Nixie tubes, but it's obsolete now. I don't even think you could buy it's not available in LS or HC or any of the other families.

It's seven, four, I think it's the seven for one for one, is it? And yeah, no, we'll find another solution. So of course, one easy solution is we can just get shift registers. you know, seven for HC to five nines or something like that, whatever your favorite latched shift register solution is. And then we can just power external high voltage transistors like that.

But you need ten of them. So we're going to look at. we would need eighty. Let's say eighty eight external transistors plus Ata the external resistors.

Then you got to solder those all on the board. or naw, that's not fun. So yeah, maybe you know that's the easy. that's the jellybean solution.

But we'll see if we can now find an off-the-shelf chip to do it. If we can't find a suitable off-the-shelf solution that's readily available at a reasonable cost, then we'll go for the external transistors. But I'm just sort of like reducing external parts count by trying to do that because we don't need. If we find a direct solution like this.

we don't need the external resistance, so we save eighty eight resistors in our circuit. We don't need the eighty-eight transistors as well. And because we've only got the one dropper up here per display. so I like the direct drive solution, you get an O one constant brightness.

You don't have to dick around with multiplexing and all that sort of stuff, but multiplexing if you are really short on space and everything else. Maybe you'd use a multiplex solution. But now I'm going to go for direct drive now if you're were going for an external transistor solution. as I said, it's got to be I've always transistors so you can't just use some sort of jellybean thing like a double to double to.

for example, it's only got 40 volts collector emitter voltage for example, you can't use like a classic bc547c. The Business: We need a high voltage transistor, so let's do a parametric search so that's pretty easy. just going to your parametric our search engine of choice: I'm going to use digi-key here I'm in discreet Bj T transistors and look at a look at MOSFETs Nice hardy Bjts. We want an NPN of course so we got to fill apply filter.

we've still got 9000 or something of those and then we're going to do the collector emitter breakdown voltage. Boom boom Boom! Let's say 200 volts and above I Mean you know now we're getting like we don't really want a massive voltage up there I Mean you could go right up to 1200 volts but we're talking about, you know, ridiculous sort of transistors? I'm going to just go say 200 to 400 for argument's sake here we go in there. And here we go: if Mmt Four Five Eight, if you want a surface mount job' BST 39s And of course you could sort by your breakdown voltage here. No worries whatsoever and all you can choose.

You know, if you wanted a through-hole solution, you go for a through-hole Yes! nice. SOT 2 to 3 package. They're one of my favorites. They're just like really nice to solder I Just enjoy solder in those anyway.

Um, yet there's no shortage of high voltage transistors to choose from. And of course, if you want to define you know what is the jellybean 1 then generally our sort by price is probably going to get that for you. You know, 2 cents a pop? There you go, half 2.6 cents. but that is in our 10000 quantity.

But yeah, there's no shortage of all. There's a through-hole at 165 1 7 more. so you just pick out a datasheet for a couple of these and any of these will do the job. This is the 2.6 cent job.

There we go. You know, 3 under volts and collector base voltage 300 volts, 200 volts any? No problems whatsoever. The 4 5 8 series here available in either a SOT 23 which is really nice and small I'd Just be careful of the you know, having your traces to close at high voltages on your PCB and stuff like that. Just watch your clearances or the two to three package as well and it's these are all going to do the business.

400 volts? No worries. Now if you were going to go for the external wire transistor solution then you would need a Well, you would like to have a one of 10 decoder. In this case, here's the seven for one for one which is now a completely obsolete and this one does have the building driver transistors for the Nixie tube display here and a one of ten decoder is basically just A for binary inputs here and it turns on one of ten outputs and that's exactly what you want because you know what any. It's not a seven segment display.

It's not like you're going to have two outputs on at the same time. Now you know you can go in and search digi-key I Just actually search for one of 10 decoder and you know and up come the usual four thousand and Seven 400 series ones. but none of these because they're obsolete. None of these are high-voltage jobbies I Don't believe.

So we're barking up the wrong tree there. Now, as I mentioned before, a good solution for this might be shifted Stirs for example. that's the one I'm looking at. So you go into logic and shift register category and bingo, What pops up first will the classic jellybean.

seven 4hc, five, Nine five. But of course they. You'd need external word drive transistors, external resistors for that. Um, and you know, hey, you could do that to choose any flavor.

But I Think that if we go in here and let's try and find one with open collector outputs and maybe we'll get lucky and find one that actually has a high voltage open collector output. So here's the output type: You don't want a complementary differential, all that sort of stuff you don't want to push, pull your totem pole output. Nope. You want open collector.

And of course you could go for our open drain as well. Hang on. How much does that? Give us a number up here? one one remaining. And if we go open drain that gives us 174.

Okay, so let's apply our filter there and let's have a look down here to 8-bit shift register. Once again, like an 8-bit one, you'd need multiple chips, one chip couldn't handle just one display because we've got ten lines. And so what we want is probably the larger packages and they're going to be more specifically designed for driving large numbers of things like this. So I you know there's I think there's more chance of there being a high voltage one in there.

so let's go from like 20 pin dip upwards shall we? So let's let's just filter out all the smaller stuff and let's take a look at what we've got. Hello, This is what I'm looking for. Anything with HV in the number HV stands for high Voltage at Microchip. Um, that's microchip.

That can't be traditional microchip. That's got to be one of the company's microchip bar bought so we can go in and have a look. But yeah, look. 220 volts.

Bingo! 32 bit serial to parallel shift register there available. Five bucks. 67 million. Oh, they're a little bit a little bit pricey, but you know it's a one-off We're only got a few of them, they've got 200 in stock.

They're in a 44 pin QFP package. Here we go. Now it is branded microchip so there you go. I Don't know if they were.

Yeah, they probably got that technology from some company they bought. would be my guess anyway. High Voltage Low our low voltage Serial - high voltage parallel converters with open drain outputs primarily design fuses driver for electroluminescent displays can also be used require multiple high voltage currency key capabilities inkjets, plasma, vacuum fluorescent, a large matrix LCD This is exactly what we want here we go: Data input, clock, strobe output enable AHA This is not a latched one so we don't want this. We want a latched type because if we try and shift data in there, you've got multiple chips.

then you actually see these things updating on the display. Don't want that? You want to shift the data in and then latch it boom all at once across all the displays. So let's have a look at another microchip one. This is a 32-bit and if we open this, bingo, it's a super text so this is where they got these from.

They just haven't changed the datasheet to what microchip yet? So sink current, hundred milliamps, no worries. I'm in jets, electrostatic electroluminescent displays and bingo latched output, data input, 32-bit shift register, and a data output. so then you can cascade it to the next one so you can have multiple ones of this. So how many chips of these do we need? Our we need three of these chips and they've got the output MOSFET drivers for driving that arm.

So what is the maximum output voltage? Here we go. Haha. 230 volts Bingo! 220 Maximum high output voltage 220. That will do the business.

thank you very much. Are they in stock there? Well, they got fifty seven in stock. You know they're seven bucks. Ninety one each.

Bit pricey, but you know we're getting towards a solution here. You can keep going and maybe try something. find a bit something bit cheaper, more available. More chili beanie maybe.

But you know there? We're out of the realms of jelly Bean Now when we start searching for a high voltage driver for these sorts of you know, specific serial driver application things, and of course you might be thinking are Dave use one of the UL in you know, 2000 series jobs. You know the two W3. Well if you go, look at those, they're all like 50 volts, 80 volts. They're like, yeah, they don't really do the business.

We can go from maximum downwards. Best one we've got here. 80 volts. Not going to do it.

Let's actually have a look at what the logic supply voltage is. You might think Arts 5 volts or 3.5 Yeah, you know that's a natural assumption. No. this one is designed for 12 volt operation Minimum ten point eight and aha does it have you know, Regular CMOS TTL compatible inputs.

Nope. The high level input voltage. Look at this VDD minus two. So to get a high on the input when you're feeding your data in your clock and everything else in your latch signal, then you need a 10 volt logic signal.

So these regular inputs here are not compared, even compatible with 5 volt. TTL Logic useless off, you're driving this from you Raspberry Pi Arduino Whatever you know, microcontroller solution you're using, it's not going to work you gather. Need a logic level translator? Every logic level translator chip or a you know, a transistor pull-up type arrangement or whatever. but you're going to need something.

What a pain in the ass. But granted, we do only have where we only have to drive one of these because they'll be cascaded together. so we only have to drive the data input. yet the data input, the clock, and the latch enable.

and well, if you're going to use the blanking line or whatever, you tie the other ones and we do have 12 volts available, we're going to. We've got that for the power supply for the high voltage power supply, so that's okay. so that's while volts kind of worked out okay. and then the data out here that would be at it at the 12 volt level so it can easily drive the input for the next one.

But yes, I only need like three logic level translator lines. So I guess that's not too bad. But ah, you know if you rushed into buying this, hooked it up and then you didn't look at that, didn't think to look at that, you would have come a gutter trap for young players. But wait, hold on to your hat.

Microchip. Have thought of everything. Look, let's go to the list against up by just microchip. they've got a 16 bit serial one in a 32 pin.

V Qfn 24 pin Are they got an 8 bit one? anyway? 486 in stock. Two bucks 20. Let's have a look at this. HV 509 shall we? It's a high voltage out back playing driver with push-pull output.

so it's got totem pole outputs. But anyway, 200 volts here. Ah, and let's go look where logic level translators. Let's go further down further down, let's have a look.

Aha Logic level supply voltage. Bingo! So it can work from 3.3 or 5 volts. No worries. A high level input voltage? Not a problem.

Anything above point Nine volts. Now we're talking so we don't need the logic level translators here. And interestingly here is this high voltage output. As I said, it's a totem pole output, but it also has an internal Vee bias here which can actually you can do current limit in with this puppy.

so we can a source or sink so it doesn't matter I Mean it doesn't matter that we've got a totem pole out, but it'll still. it's going to survive that. But here we go. Here's typical high voltage output, current sink versus the bias voltage for a two hundred volt supply and there it is.

You can set the current versus the V bias voltage, but of course that will or you could do it with this so you can actually save. Technically save a resistor on each one of those displays, so that's awesome. This chip looks like it's going to do the business. 16-bit shift registers, 16-bit latch.

It's got the data out so that we can cascade them. No worries, it's all latched and so Translator: I Think we know Winner chicken dinner except for the package Point: five millimeter pitch, 32 lead Qfn water pain in the ass but hey, if you wanted to, you could have a look at this hour 8 bit job here. Yeah, there are three bucks 23 each so they're going to be pricey. but if you didn't want to solve that pain-in-the-ass Qfn, you could use these eight bit jobs.

and they do the businesses will. Logic level Translator: 5 Volts has got data out and it's got all the goodness in an Esso 24 pin Sao package. So yeah, it's typical supply voltage 5 volt so it's compatible with typical micro controller modules and stuff like that and it's going to do the business. Got the same totem pole out but doesn't have the V bias bit in there.

You know, who cares, right? So that would do the job as well. It's just a bit more pricey anyway. I Think our 30 odd minutes of waffling is enough for part 1 here. I'm in the future.

our parts all do the schematic layout. The board talked about what my application is and stuff like that, so stay tuned. Catch you next time you.