Stacking Voltage References To High Voltage Extremes

October 3, 2016 by Jenny List 23 Comments

As children, we all probably had our ideal career paths. As an adult do you still harbor a secret desire to be an astronaut, or to drive a railroad train? Or have holders of other jobs become the people you envy?

As a Hackaday writer it’s probably not too controversial to admit a sneaking envy for the writers of semiconductor application notes. True, often their work consists of dry demonstrations of conventional uses for the products in question, but every once in a while they produce something off the wall and outside the device’s intended use, so out of the ordinary that you envy them their access for experimentation to the resources of a large semiconductor company.

Take Texas Instruments’ Application Report SBAA203, from May 2013. “Stacking the REF50xx for High-Voltage References” (PDF). A laboratory specialising in accurate measurement of high voltages had the problem that the stacks of Zener or avalanche diodes they were using as voltage references lacked both precision and stability, so investigated the properties of the REF5010 10V precision voltage reference.

You'll never be satisfied with a mere Zener diode again. — You’ll never be satisfied with a mere Zener diode again.

They found that by ignoring the device’s data sheet and directly connecting its output pin to its power pin, the REF5010 became equivalent to an ideal Zener diode. In this mode multiple references could be stacked in the same way as a real Zener diode, and very stable and high-precision voltage references could be created with very high voltages. They made a PCB with ten stacked REF5010s for a 100V reference, and then stacked ten of them for a 1000V reference. Leaving it for 24 hours to settle, they achieved a precision of +/- 2.5ppm, and after 3.5 months their average reading for the ten 1000V references they built was 1000.022V.

The 1000V reference would be impressive enough, but they weren’t finished. They built a series of boards holding 500 REF5010s for a 5KV reference, and stacked 20 of them to make a 100KV reference. These boards were mounted in a tower looking not unlike the Tesla coils we sometimes feature here. They note that it probably hits the record of simultaneous use of TI parts in a single device.

This may well be the first extremely high voltage precision reference to feature here at Hackaday, but we’ve certainly had our share of HV articles. Earlier this year we had a trio from [Steven Dufresne]: A conucopia of high voltage sources looking at ways to make your EHT, High voltage please, but don’t forget the current looking at selecting the right HV power supply for an application, and Wrangling high voltage looking at construction techniques.

Thanks [Nathan] for the tip.

Retrotechtacular: Power Driven Articulated Dummy

September 27, 2016 by Jenny List 18 Comments

If any of you have ever made a piece of clothing, you’ll know some of the challenges involved. Ensuring a decent and comfortable fit for the wearer, because few real people conform exactly to commercial sizes. It’s as much a matter of style as it is of practicality, because while ill-fitting clothing might be a sartorial fail, it’s hardly serious.

When the piece of clothing is a space suit though, it is a different matter. You are not so much making a piece of clothing as a habitat, and one that will operate in an environment in which a quick change to slip into something more comfortable is not possible. If you get it wrong at best your astronaut will be uncomfortable and at worst their life could be threatened.

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Now Is The Golden Age Of Artisanal, Non-Traditional Tube Amps

September 24, 2016 by Mike Szczys 17 Comments

Earlier in the month, [Elliot Williams] quipped that it had been far too long since we saw a VFD-based amplifier build. Well, that dry spell is over. This week, [kodera2t] started showing off his design for a VFD headphone amp.

Here’s the thing, this isn’t using old surplus vacuum fluorescent displays. This is actually a new part. We first covered it about 18 months ago when Korg and Noritake announced the NuTube. It’s the VFD form factor you would find in old stereo and lab equipment, but housed in the familiar glass case is a triode specifically designed for that purpose.

Check out [kodera2t’s] video below where he walks through the schematic for his amplifier. Since making that video he has populated the boards and taken it for a spin — no video of that yet but we’re going to keep a watchful eye for a follow-up. Since these parts can be reliably sourced he’s even planning to sell it in his Tindie store. If you want to play around with this new tube that’s a pretty easy way to get the tube and support hardware all in one shot. This is not a hack, it’s being used for exactly what Korg and Noritake designed it to do, but we hope to see a few of these kits hacked for specific tastes in amp design. If you do that (or any other VFD hacking) we want to hear about it!

And now for the litany of non-traditional VFD amps we’ve grown to love. There is the Nixie amp where [Elliot] made the quip I mentioned above, here’s an old radio VFD amp project, in this one a VCR was the donor, and this from wayback that gives a great background on how this all works.

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Hackaday Prize Entry: Dodo 6502 Game System

September 22, 2016 by Jenny List 13 Comments

If you are a gamer of A Certain Age, it’s probable that you retain a soft spot for 8-bit computers and consoles of your youth. For a time when addictive gameplay came through the most minimal of graphics, and when gaming audio was the harshest of square waves rather than immersive soundscapes.

Does the previous paragraph sound familiar? Then we may just have the device for you. The Dodo is a handheld console that harks back to that era with a 6502 processor and a 128×64 pixel OLED screen. Games are loaded from plug-in EEPROM cartridges, and sounds are suitably period-digital square wave tones. It’s the brainchild of [Peter Noyes], and he says he will consider it complete when it sports a game fun enough to entertain his 4-year-old.

The prototype Dodo is a handheld form-factor made from two stacked PCBs. The upper one has the display and buttons while the lower has the classic 6502 and associated chipset in through-hole DIP format. A Game Boy Micro it ain’t, but miniaturization is not the name of the game with these consoles. Best of all though, all the console’s resources are available in a GitHub repository, so you can all have a play too.

The 6502 has featured in a huge number of projects here on Hackaday over the years. Now it’s turned up in the Hackaday Prize.

Electric Train Demonstrator

September 22, 2016 by Al Williams 26 Comments

If you ever want to pique a kid’s interest in technology, it is best to bring out something simple, yet cool. There was a time that showing a kid how a crystal radio could pull in a radio station from all the way across town fit the bill. Now, that’s a yawner as the kid probably carries a high-tech cell phone with a formidable radio already. Your latest FPGA project is probably too complicated to grasp, and your Arduino capacitance meter is–no offense–too boring to meet the cool factor criterion.

There’s an old school project usually called an “electromagnetic train” that works well (Ohio State has a good write up about it as a PDF file). You coil some bare copper wire around a tubular form to make a tunnel. Then a AAA battery with some magnets make the train. When you put the train in the tunnel, the magnetic forces propel the train through the tunnel. Well, either that or it shoots it out. If that happens, turn the train around and try again. There’s a few of these in Internet videos and you can see one of them (from [BeardedScienceGuy]) below.

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A New OS For Apple II Computers

September 16, 2016 by Brian Benchoff 33 Comments

Although this sort of work is usually reserved for KansasFest and other forums for highly technical and very skilled Apple enthusiasts, [John Brooks]’s release of a new version of the ProDOS operating system is no less important. It is, without a doubt, the greatest release the Apple II platform will see for the next few years. This swan song of the Apple II platform is simply ProDOS 2.4, an update to the last version of Apple’s ProDOS, last released in 1993.

For a bit of historical context, ProDOS was not the operating system that shipped with the Apple ][ in 1977. That OS was simply called DOS. ProDOS, released in 1983, included support for the new 3.5″ floppy drives, allowed for hierarchical directories, supported hardware interrupts, and kept the Apple ][ line going well into the 90s. Despite these improvements, not all Apple ][ systems were supported. The original ][ and ][+ were out in the cold. Now, with the ability to add Compact Flash and USB devices to an Apple ][, even the latest version of ProDOS is horribly out of date.

[John]’s release of ProDOS 2.4 fixes all of this. This release is the most important development in the Apple ][ ecosystem in recent memory, and will remain so for at least a decade. The only person who still uses an Apple ][ as a daily driver agrees, and ProDOS 2.4 is now enshrined in The Archive for all eternity.

New features abound, although most of them are geared toward the now thirty-year-old Apple IIGS. These features include enhanced utility in GS/OS – the Apple equivalent of the Commodore GEOS – slot remapping, and an OS that is both smaller and loads faster. Older machines aren’t left out, and ProDOS includes the usual features and improvements found in ProDOS 2.x that weren’t available in the Apple ][, Apple ][+ and un-enhanced Apple //e.

The killer feature and one more thing of this release is the BitsyBye utility, a small ($300!) system program that allows you to boot various Apple II devices and programs. Think of this as the Norton Commander of the Apple II ecosystem, allowing slots to be selected, booting the most recently used ProDOS device, and basic file system exploration. BitsyBye also includes an easter egg. A few utilities are also included on the ProDOS 2.4 disk image including ADTPro, Shrinkit archive expander, and disk utilities.

A 140k ProDOS 2.4 disk image is available on [John]’s site and on Archive.org. Since you’re probably not downloading directly to an Apple II disk, grab ADTPro and load it over audio.

The Surprising Story Of The First Microprocessors

September 15, 2016 by Jenny List 16 Comments

If you maintain an interest in vintage computers, you may well know something of the early history of the microprocessor, how Intel’s 4-bit 4004, intended for a desktop calculator, was the first to be developed, and the follow-up 8008 was the first 8-bit device. We tend to like simple stories when it comes to history, and inventions like this are always conveniently packaged for posterity as one-off events.

In fact the story of the development of the first microprocessors is a much more convoluted one than it might appear, with several different companies concurrently at the forefront of developments. A fascinating recent IEEE Spectrum piece from [Ken Shirriff] investigates this period in microprocessor design, and presents the surprising conclusion that Texas Instruments may deserve the crown of having created the first 8-bit device, dislodging the 8008 from its pedestal. Continue reading “The Surprising Story Of The First Microprocessors” →