Hackaday Prize Entry: Hot Logic

April 15, 2017 by 33 Comments

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.

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Mains Clocking A Microcontroller

April 15, 2017 by 34 Comments

[Lujji] is playing around with the STM8 microcontroller. In reviewing the official documentation for this chip, he read the external clock can be a sine wave, a triangle wave, or a square wave with a 50% duty cycle. The minimum CPU frequency is 0 Hz. [Lujji] doesn’t have a signal generator, and presumably, he’s all out of crystals. He does have mains AC, though, so why not clock a microcontroller with wall power?

Using mains power as a frequency standard is a concept a hundred years old. Synchronous motors turn at a rate proportional to the mains frequency, and this has been used in clocks for decades. If you’re really clever, you can clock digital circuits with mains AC, but we’ve never seen someone replace a tiny crystal in a microcontroller circuit with mains power.

After an experiment to prove the concept, [Lujji] went on to construct a circuit that wasn’t as dumb as connecting the microcontroller directly to a wall socket. The direct approach didn’t work that well anyway — the STM8 didn’t like low frequency clocks with slow edges. [Lujji] needed a clock with cleaner edges, and a 555 configured as a comparator fit the bill.

The completed circuit sends mains power through an optocoupler to drive a 555 configured as a comparator. The output is a clean 50Hz clock that is connected to the OSCIN pin on an STM8. This is now a chip running at 50Hz, and yes, it works. [Lujji] set up a circuit to write ‘Hello World’ on an old Nokia LCD. That took about three minutes. It works, though, even though it’s completely useless. Maybe this can be applied to some novel timekeeping similar to that one-instruction-per-day clock we looked earlier in the year.

An Even Smaller BeagleBone

April 15, 2017 by 51 Comments

The BeagleBone famously fits in an Altoids tin. Even though we now have BeagleBone Blacks, Blues, and Greens, the form factor for this curiously strong Linux board has remained unchanged, and able to fit inside a project box available at every cash register on the planet. There is another Altoids tin, though. The Altoid mini tin is just over 60×40 mm, and much too small to fit a normal size BeagleBone. [Michael Welling] has designed a new BeagleBone to fit this miniature project box. He’s calling it the Pocketbone, and it’s as small as the mints are strong.

The Pocketbone is based on the Octavo Systems OSD355x family, better known as the ‘BeagleBone on a chip’. This chip features a TI AM355x ARM Cortex A8, up to 1GB of DDR3 RAM, 114 GPIOs, 6 UARTs, 2 SPIs, 2x Gigabit Ethernet, and USB. It’s housed in a relatively large BGA package that makes routing easy, and as a proof of concept [Jason Kridner] built a PocketBone in Eagle.

[Michael]’s version of the Pocketbone is based on the earlier proof of concept, with a few handy additions. There’s an IO expansion header, provisions for a battery input, a few fixes to the USB, and all the parts are on one side of the board facilitating easier assembly. This version of the Pocketbone was created using KiCad, which will endear the project to the Open Source community.

Measuring Capacitors At The Birth Of Rock And Roll

April 15, 2017 by 3 Comments

The late 1950s [Bill Haley], [Elvis Presley], and [Little Richard] were building a new kind of music. Meanwhile, electronic hobbyists were building their own gear from Heathkit. A lot of that gear shows you how far we’ve come in less than a century. [Jeff Tranter’s] YouTube channel is a great way to look at a lot of old Heathkit gear, including this really interesting “direct reading capacity meter.” You can see the video, below.

Measuring capacitance these days is easy. Many digital multimeters have that function. However, those didn’t exist in the 1950s–at least, not in the way we know them. The CM-1 weighed 5 pounds, had several tubes, and cost what would equate to $250 in today’s prices. Unlike other instruments of the day, though, the capacitance was read directly off a large analog meter (hence, the name). You didn’t have to interpret readings using a nomograph or move a knob to balance a bridge and read the knob’s position.

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High Vacuum With Mercury And Glassware

April 15, 2017 by 32 Comments

If you want to build your own vacuum tubes, whether amplifying, Nixie or cathode-ray, you’re going to need a vacuum. It’s in the name, after all. For a few thousand bucks, you can probably pick up a used turbo-molecular pump. But how did they make high vacuums back in the day? How did Edison evacuate his light bulbs?

Strangely enough, you could do worse than turn to YouTube for the answer: [Cody] demonstrates building a Sprengel vacuum pump (video embedded below). As tipster [BrightBlueJim] wrote us, this project has everything: high vacuum, home-made torch glassware, and large quantities of toxic heavy metals. (Somehow [Jim] missed out on the high-voltage from the static electricity generated by sliding mercury down glass tubes for days on end.)

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PassivDom: Mobile Homes For Millenials

April 14, 2017 by 79 Comments

In many parts of the world, living in a trailer has gained a social stigma. We’re talking about a rectangular building placed on three wheels and towed to your preferred plot of land. It’s going to take a lot to break that social stigma, but this is a pretty sweet attempt.

PassivDom is an off-grid home. It sidesteps the electrical grid as well as water and sewer service. It’s marketed as utilizing revolutionary breakthrough in wall insulation which they claim makes it very easy to heat and cool. In addition to this self-sustaining angle, it taps into the tiny home movement with a footprint of just 36 m2 (4 m by 9 m; about 118 390 ft2 or 13′ by 30′).

For this to make sense you really need to get the “Autonomous” model, the only one that is designed for “off-grid” living and comes with solar panels and battery storage plus water storage and purification. That’ll set you back 59,900 € (about $63,461 USD) but hey, it does come with “high quality minimalistic furniture” which the best way we can think of to serve Ikea nesting instinct without saying the brand name. Yep, this ticks all the “marketing to millennials” boxes. We’re kind of surprised it’s not doing crowdfunding.

So where’s the hack? Obviously this is a hard sell at 1,664 €/m2 ($538 $163/ft2). A project of this size and scope is well within the purview of a single, motivated hacker, and arguably a weekend project for a well-skilled team from a hackerspace. Tiny Houses started as a build-it yourself so that’s already solved. We’ve seen what it takes for hackers to add solar to their RVs, and experiments in home-built power walls. Water storage and purification is already solved and quite affordable at the home store.

Has anyone built their own off-grid tiny house? If so, let us know what went into it. If not, what are you waiting for?

Build Your Own PC — Really

April 14, 2017 by 37 Comments

There was a time when building your own computer meant a lot of soldering or wire wrapping. At some point, though, building a PC has come to mean buying a motherboard, a power supply, and just plugging a few wires together. There’s nothing wrong with that, but [Scott Baker] wanted to really build a PC. He put together an Xi 8088, a design from [Sergey] who has many interesting projects on his site. [Scott] did a great build log plus a video, which you can see below.

As the name implies, this isn’t a modern i7 powerhouse. It is a classic 8088 PC with a 16-bit backplane. On the plus side, almost everything is conventional through-hole parts, excepting an optional compact flash socket and part of the VGA card. [Scott] acquired the boards from the Retrobrew forum’s inventory of boards where forum users make PCBs available for projects like this.

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