Neon Display for a Vacuum Tube Calculator

When it comes to vintage displays, everyone gravitates to Nixies. These tubes look great, but you’re dealing with a certain aesthetic with these vintage numeric tubes. There is another option. For his Hackaday Prize entry, [castvee8] is making seven-segment displays out of vintage neon lamps. It looks great, and it’s the basis of an all-vacuum tube calculator.

The core of this build are a few tiny NE-2 neon bulbs. These are the same type of bulbs you’ll find in old indicators, and require somewhere around 100 volts to fire. These bulbs are then installed in a 3D-printed frame, giving [castvee] a real seven-segment display, a plus or minus sign, and an equals sign. It’s the beginnings of a calculator, right there.

One of the recent updates to this project is controlling these displays with modern logic. That might be a bit of a misnomer, because [castvee] is using diode steering and a TTL chip to cycle through the numbers 1 to 4. The actual code to do this is running on a microcontroller, though, so that might get a pass. This is just a test, though, and the real project looks to be an all-vacuum calculator. The project is still in its early stages, but there are still months to go in the Hackaday Prize, and we can’t wait to see what comes out of this project.

A Pin Pusher To Make Life Easier

Picture the scene: you’ve whipped up an amazing new gadget, your crowdfunding campaign has gone well, and you’ve got a couple hundred orders to fill. Having not quite hit the big time, you’re preparing to tackle the production largely yourself. Parts begin to flood in, and you’ve got tube after tube of ICs ready to populate your shiny new PCBs? After the third time, you’re sick and tired of fighting with those irksome little pins. Enter [Stuart] with the answer.

It’s a simple tool, attractively presented. Two pieces of laser cut acrylic are assembled in a perpendicular fashion, creating a vertical surface which can be used to press pins out of IC tubes. [Stuart]’s example has rubber feet, though we could easily see this built into a work surface as well.

The build highlights two universal truths. One, that laser cutters are capable of producing elegant, visually attractive items almost effortlessly, something we can’t say about the garden variety 3D printer. Secondly, all it takes is a few little jigs and tools to make any production process much easier. This is something that’s easy to see in the many factories all over the world – special single-purpose devices that make a weird, tricky task almost effortless.

In DIY production lines, testing is important too – so why not check out this home-spun test jig?

Vacuum Tubes: Shipping Through EBay Now Challenging?

There is disquiet in the world of vacuum electronics, that something as simple as shipping a vacuum tube could now be very difficult to achieve. It’s a concern expressed among other places in a video by [Guitologist] that we’ve included below, and includes tales of vacuum tubes being impounded as either dangerous to ship, or not allowed to be shipped across international borders.

Upon investigation it appears that the common thread in all the stories lies with eBay’s Global Shipping Program, the centralised shipping service operated by the online auction giant. We reached out to eBay’s press office on the subject but have yet to receive a reply. It’s best to ask someone who ships a lot of tubes for comment when you have a tube shipping story, so we also had a conversation with TC Tubes. They’re a small company dealing in tubes, and as you might imagine they ship a lot of them (Their website is likely to detain you for a while if you are a tube-head). [Chelsea] from TC Tubes told us that they have encountered no regulatory barriers to tube shipping, and that their only bad experience has been yet again with eBay’s Global Shipping Program.

So it seems there is no cause for panic if you ship tubes, CE marking or RoHS rules haven’t come for your EL34s and your 6550s. Ebay have evidently got some kind of issue with tubes in their shipping operation, and perhaps you should ship by other means if you wish to avoid your tubes going astray. The consensus here among the Hackaday crew is that it could be as simple as uninformed employees not being aware of what tubes are because they aren’t as common as they used to be. After all, with over a hundred years of history behind them it’s not as though any potential issues with their shipping haven’t been comprehensively explored.

We’d still be interested to hear from eBay on the matter though, if they would care to comment.

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Hackaday Prize Entry: Hot Logic

A few weeks ago, [Yann] was dumpster diving and found something of interest. Two vacuum tubes, an ECC83S and an EL84. This was obviously the droppings of a local guitarist, but [Yann] wanted to know if he could build something useful out of them. An amplifier is far too pedestrian, so he settled on a vacuum tube computer.

The normal pentodes and triodes you’ll find in a tube amp require a lot of support components like output transformers, tube sockets, and high voltage power supplies. This was a little too complicated for a tube computer, but after a little bit of searching, [Yann] found a better option for his MINIVAC — subminiature vacuum tubes. These require fewer support components, and can be found for very reasonable prices through the usual component suppliers. His entry for this year’s Hackaday Prize is Hot Logic. It’s a computer — or at least computer components — built out of these tubes.

The tubes in question are a few 1Ж29Б-В and 6Н21Б tubes, a vacuum pentode and dual triode, respectively. Add in a few diodes, and that meets the requirements for being sufficient to build a computer. As a neat little bonus, these tubes have requirements that are very easy to meet. The filament on the 1Ж29Б-В tube only needs 1.2 Volts.

These subminiature tubes are a little underappreciated in the world of audiophililia and DIY electronics. That’s a bit of a shame; these tubes are the most technologically advanced vacuum-based technology ever created. They were the heart and the brains of ballistic missiles, and if you look hard enough you source hundreds of them at very reasonable prices. A vacuum tube computer requires a lot of tubes, and if anyone will be able to build a vacuum tube computer it’s going to be [Yann] and his pile of Soviet surplus.

Hot Russian Tubes

On the heels of our post on retro-Soviet transistor teardowns and die-shots, [nikitas] wrote in to tell us about a huge thread on rare vacuum devices of all varieties: oddball cathode-ray tubes, obscure Nixies, and strange Soviet valves. We thought the other forum post was overwhelming at just over 110 pages, but how about 391 pages (and counting) of blown-glass electronics?

If you read through the decaptholon, we mentioned that a particularly enthusiastic poster, [lalka], looked to be cataloguing every Soviet oscillator circuit. It turns out that he’s also the one behind this incredible (random) compendium of everything that’s had the air sucked out of it.

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Flying Close To The Flame: Designing Past Specified Limits

A very good question came up on The EEVBlog forum that I thought deserved an in depth answer. The poster asked why would amplifier companies in the heyday of tube technology operate tubes in mass produced circuits well in excess of their published manufacturers recommended limits. The simple answer is: because the could get away with it. So the real question worth exploring is how did they get away with operating outside of their own published limitations? Let’s jump in and take a look at the collection of reasons.

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Tubes on a Chip

The tubes you’ll find in guitar amps and high-end stereos were first designed in the 30s and 40s, and when you get to really, really advanced tube technology you’d be looking at extremely small tubes made in the 70s for military applications. For 40 years, there really haven’t been many advances in tube technology. Now, at last, there’s something new.

The Nutube 6P1, as this curious invention is called, is a full triode or half of a 12ax7 you’ll find in just about every tube amp ever. Unlike the 12ax7, it consumes 2% of the power required of a normal tube, is 30% of the size of the normal tube, and lasts for 30,000 hours.

This new tube-chip thing was brought to life by Korg, makers of fine musical equipment and Noritake Co., manufacturers of vacuum fluorescent displays. There’s no word on what these tubes will be used in and there’s no data sheet. There will be further announcements this year, so don your speculation spectacles and head to the comments.