Play DOOM On Seven-Segment Displays

October 29, 2022 by Bryan Cockfield 12 Comments

Getting DOOM to run on a computer it was never meant to run on is a fun trope in the world of esoteric retro computers. By now we’ve seen it run on everything from old NES systems to microwaves, treadmills, and basically anything with a computer inside of it. What we don’t often see are the displays themselves being set up specifically to run the classic shooter. This build might run the game itself on ordinary hardware, but the impressive part is that it’s able to be displayed on this seven-segment display.

This build makes extensive use of multiplexers to drive enough seven-segment displays to use as a passable screen. There are 1152 seven segment digits arranged in a 48 by 24 array, powered by a network of daisy-chained MAX7219 chips. A Python script running on a Raspberry Pi correlates actual image data with the digit to be displayed on each of the segments, and the Raspberry Pi sends all of that information out to the screen. The final result is a display that’s fast enough and accurate enough to play DOOM in a truly unique way.

There is much more information available about this project on their project page, and they have made everything open source for those who wish to follow along as well. The project includes more than just the ability to play DOOM, too. There’s a built-in video player and a few arcade programs programmed specifically to make use of this display. Perhaps one day we will also see something like this ported to sixteen-segment displays instead of the more common seven-segment.

A Homemade Tube Amplifier Featuring Homemade Tubes

October 27, 2022 by Dan Maloney 23 Comments

With the wealth of cheap and highly integrated audio amplifier modules on the market today, it takes a special dedication to roll your own from parts. Especially when those parts include vacuum tubes, and doubly so when you make the vacuum tubes from scratch too.

Now, we get it — some readers are going to find it hard to invest an hour in watching [jdflyback] make a pair of triodes to build his amplifier. But really, you’ve got to check this out. Making vacuum tubes with all the proper equipment — glassblower’s lathe, various kinds of oxy-fuel torches, all the right hand tools — is hard enough. But when your lathe is a cordless drill, and you’re using a spot welder that looks like it’s cobbled together from junk, your tube-making game gets a lot harder. Given all that, you’d expect the tubes to look a lot rougher than they are, but even with plain tungsten wire heaters and grids made from thick copper wire, they actually work pretty well. Sure, the heaters glow as bright as light bulbs, but that’s all part of the charm.

Speaking of charm, we just love the amp these tubes went into. Built in 1920s breadboard-style, the features some beautiful vintage mica capacitors and wirewound resistors, plus a variable resistor the likes of which we’ve never seen. The one nod to modernity is the clever use of doorbell transformers, one for a choke and one for the speaker transformer. They don’t sound great, but there’s no doubt they work.

We may have seen other homemade vacuum tubes before — we even recently featured a DIY X-ray tube — but there’s something about [jdflyback]’s tubes that really gets us going.

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Kodak Film Factory Revealed

October 18, 2022 by Dave Walker 51 Comments

Anybody born before the mid 1990s will likely remember film cameras being used to document their early years. Although the convenience of digital cameras took over and were then themselves largely usurped by mobile phones, there is still a surprising variety of photographic film being produced. Despite the long pedigree, how many of us really know what goes into making what is a surprisingly complex and exacting product? [Destin] from SmarterEveryDay has been to Rochester, NY to find out for himself and you can see the second in a series of three hour-long videos shedding light on what is normally the strictly lights-out operation of film-coating.

Kodak first digital camera 1975 — Kodak’s first attempt at a digital camera in 1975. The form-factor still left something to be desired…

Kodak have been around in one form or another since 1888, and have been producing photographic film since 1889. Around the turn of the Millennium, it looked as though digital photography (which Kodak invented but failed to significantly capitalize on) would kill off film for good, and in 2012 Kodak even went into Chapter 11 bankruptcy, which gave it time to reorganize the business.

They dramatically downsized their film production to meet what they considered to be the future demand, but in a twist of fortunes, sales have surged in the last five years after a long decline. So much so, in fact, that Kodak have gradually grown from running a single shift five days per week a few years ago, to a 24/7 operation now. They recently hired 300 Film Technicians and are still recruiting for more, to meet the double-digit annual growth in demand.

[Destin] goes to great lengths to explain the process, including making a 3D model of the film factory, to better visualize the facility, and lots of helpful animations. The sheer number of steps is mind-boggling, especially when you consider the precision required at every step and the fact that the factory runs continuously… in the dark, and is around a mile-long from start to finish. It’s astonishing to think that this process (albeit at much lower volumes, and with many fewer layers) was originally developed before the Wright Brothers’ first powered flight.

We recently covered getting a vintage film scanner to work with Windows 11, and a little while back we showed you the incredible technology used to develop, scan and transmit film images from space in the 1960s.

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Why Learn Ancient Tech?

October 15, 2022 by Elliot Williams 69 Comments

The inner orbits of the Hackaday solar system have been vibrating with the announcement of the 2022 Hackaday Supercon badge. The short version of the story is that it’s a “retrocomputer”. But I think that’s somehow selling it short a little bit. The badge really is an introduction to machine language or maybe a programming puzzle, a ton of sweet blinky lights and clicky buttons, and what I think of as a full-stack hacking invitation.

Voja Antonic designed the virtual 4-bit machine that lives inside. What separates this machine from actual old computers is that everything that you might want to learn about its state is broken out to an LED on the front face, from the outputs of the low-level logic elements that compose the ALU to the RAM, to the decoder LEDs that do double-duty as a disassembler. You can see it all, and this makes it an unparalleled learning aid. Or at least it gives you a fighting chance.

So why would you want to learn a made-up machine language from a non-existent CPU? Tom Nardi and I were talking about our experiences on the podcast, and we both agreed that there’s something inexplicably magical about flipping bits, calling the simplest of computer operations into action, and nonetheless making it do your bidding. Or rather, it’s anti-magical, because what’s happening is the stripping away of metaphors and abstractions. Peering not just behind, but right through the curtain. You’re seeing what’s actually happening for once, from the bottom to the top.

As Voja wrote on the silkscreen on the back of the badge itself: “A programmer who has never coded 1s and 0s in machine language is like a child who has never run barefoot on the grass.” It’s not necessary, or maybe even relevant, but learning a complex machine in its entirety is simultaneously grounding and mind-expanding. It is simply an experience that you should have.

Printed Axial Generator Is Turned By Hand

October 15, 2022 by Bryan Cockfield 19 Comments

While desktop 3D printing is an incredible technology, it’s got some pretty clear limitations. Plastic parts can be produced quickly in a 3D printer but can be more expensive or take longer to make than parts from materials like wood. Plastic parts can also be weaker than materials like metal. If a 3D printer is all you have on hand, though, you can often make some design choices that improve the performance of a plastic part over other materials. That’s what [1970sWizard] did to make this axial hand-cranked generator.

Besides a few pieces of off-the-shelf hardware and the wire and magnets, the entire generator is printed. The actual generator is made from coils of wire with exposed leads which snap into a plastic disc which acts as the generator’s stator. The magnets also snap into a separate disc which is the rotor of the generator and is attached to the drivetrain, with no glue or fasteners required. A series of gears on two other axes convert the torque from the hand crank into the high speed necessary to get usable electricity out of the generator.

The separate gear shafts were necessary to keep from needing a drillpress, which would have allowed fewer axes to be used. This entire machine can be built almost entirely with a desktop 3D printer, though, which was one of the design goals. While it’s largely a proof-of-concept, the machine does generate about 100 mW of power which is enough to slowly charge USB devices, power lights, or provide other sources of very small amounts of energy. If you do have access to some metalworking tools, though, take a look at this hand-cranked emergency generator.

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Amateur Rocket Aims For The Kármán Line, One Launch At A Time

October 10, 2022 by Ryan Flowers 17 Comments

When it comes to high-powered rocketry, [BPS.space] has the unique distinction of being the first to propulsively land a solid-fueled model rocket. How could he top that? Well, we’re talking about actual rocket science here, and the only way is up! All the way up to the Kármán line: 100 km. How’s he going to get there? That’s the subject of the video below the break.

Getting to space is notoriously difficult because it’s impossible to fully test for the environment in which a rocket will be flying. But there is quite a lot that can be tested, and those tests are the purpose of a rocket that [Joe] at [BPS.space] calls Avalanche. Starting with a known, simple design as a test bed, numerous launches are planned in order to iterate quickly through several launches- three of which are covered just in this video.

The goal with Avalanche isn’t to get to the Kármán line, but to learn the lessons needed to build a far bigger rocket that will. A home-brewed guidance system, a gimballed spin-stabilized 4K camera, and the descent system are among those being tested and perfected.

Of course, you don’t have to be a rocket scientist to have fun with prototyping. Sometimes you just want to 3D print a detonation engine, no matter how long it won’t last. Why not?

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A CRT Monitor From An Obsolete Logic Analyzer

October 7, 2022 by Jenny List 15 Comments

The designers of older equipment that contained a CRT monitor rarely made the effort to design their own driver and deflection circuitry. Instead they were more likely to buy an off the shelf assembly from a monitor manufacturer, and simply supply it with their video. [TomV] has an old HP 16500A logic analyzer, and in it he found a Sony monitor chassis. With a quest for a microfiche service manual and a bit of reverse engineering, he was able to hook it up to a VGA port and use it as an extension monitor for his laptop.

The monitor chassis is a Sony CHM-9001-00, which sports their 10″ Trinitron tube. These were among the very best CRT tubes of the day, making it the type of module 1990s hacker would have been very pleased to get their hands on. Here in 2022 a look at the monitor’s 40-pin connector reveals a standard RGB interface which the service manual confirms is within the voltage range to be driven from a VGA output. A Thinkpad X220 is pressed into service, with a 576 by 360 pixel at 60 Hz video mode defined, and there we have it, a modern desktop on an obsolete piece of test equipment.

The intended destination for this monitor is a small arcade cabinet, so it needed to be independent of the HP chassis. The required 120 VDC supply comes from an inverter designed for solar battery charging, which balked at the inrush current from the monitor when fed with 12 V. Increasing the supply voltage on the low voltage side solved that, leading to a very serviceable monitor. We have no use for one, but we’d be lying if we said we didn’t want one.

Perhaps you may have wondered, what made Trinitrons so good?