classic hacks

2767 Articles

Dumpster Dive Speaker Results In Tube Amplifier

March 18, 2017 by 14 Comments

[Michael Wiebusch] found the leftovers of a wrecked vintage tube radio in a pile of electronics junk. Unfortunately, he could not recover any vacuum tubes in it. And to his dismay, it didn’t even have the output transformer, which he figured would have been useful in a guitar amplifier project. The output transformer is not easy to come by nowadays, so he was hoping to at least score that item for his future build. All he could dig out from his dumpster find was a pair of speakers and he ended up building nice Output-Transformer-Less Tube Guitar Amplifier around them.

Valve output stages are generally high-impedance which means they cannot be directly interfaced to low impedance speakers. An impedance matching output transformer is thus used to interface the two. Back in the day when valves were still the mainstay of audio electronics, many cheap amplifier designs would skimp on the output transformer to save cost, and instead use high impedance speakers connected directly to the amplifier output.

[Michael] found a nice reference design of an OTL amplifier for a 620 ohm single speaker. He decided to use the same design but because these speakers were about 300 ohm each, he would have to wire his two speakers in series. At this point, he decided to make his build useful as a proper guitar amplifier by adding a preamplifier stage replicated from another design that he came across. A regular halogen lamp 12V transformer takes care of the heater power supply for all the tubes, and a second, smaller 12V transformer is wired backwards to provide the 300V needed for the plate supply.

The final result is pretty satisfactory, considering that it all started with just a pair of junked speakers. Check out the result in the video after the break.

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Line Follower Has Lots Of Recycled Parts, But Zero Brains

March 18, 2017 by 20 Comments

Line Followers are a tried-and-true type of robot; both hardware and software need to be doing their job in harmony in order to be successful at a clearly defined physical task. But robots don’t always have microcontrollers and software, as [Mati_DIY]’s zero programming analog line follower demonstrates.

For readers used to seeing a Raspberry Pi or Arduino in almost everything, an analog robot whose “programming” exists only as a harmony between its discrete parts can be an eye-opener as well as an accessible project. A video of the robot in action is embedded below.

[Mati_DIY]’s design uses two CNY70 reflective sensors (which are essentially infrared emitter/phototransistor pairs) and an LM358 dual op-amp. Together, the sensors act as two near-sighted eyes. By using the output of each sensor to drive a motor via a transistor, the presence or absence of the black line is directly and immediately reflected by the motion of the attached motor. The more black the sensor sees, the more the motor turns. Electrically, that’s all that happens; but by attaching the right sensor to the left motor and the left sensor to the right motor, you get a robot that always tries to keep the black line centered under the sensors. Playing with the spacing of the motors and sensors further tweaks the performance.

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There’s A Mew Underneath The Truck Next To The SS Anne

March 17, 2017 by 26 Comments

Before we dig into this, I need to spend a paragraph or two conveying the knowledge of a twelve-year-old in 1996. Of course, most Hackaday readers were twelve at least once, but we’re just going to do this anyway. The payoff? This is an arbitrary-code-execution virus for Pokemon, and maybe the most amazing Game Boy hack of all time.

In the first generation of Pokemon games, there is a spectacularly rare Pokemon. Mew, the 151st Pokemon, could learn every move in the game. It was a psychic type, which was overpowered in the first gen. You could not acquire a Mew except by taking your Game Boy to a special event (or to Toys R Us that one time). If someone on the playground had a Mew, they really only had a GameShark.

There was a mythos surrounding Mew. Legend said if you went to the SS Anne and used Strength to move a truck sprite that appeared nowhere else in the game, a Mew would appear. Due to the storyline of the game, you didn’t have the ability to get to this truck the first time you passed it. However, if you started a new game – thus losing all your progress and your entire roster of Pokemon – you could test this theory out. Don’t worry, you can just trade me all your good Pokemon. I’ll give them back once you have a Mew. Screw you, Dylan. Screw you.

Now the Mew truck trick is real. You can do it on a copy of Red or Blue on an original Game Boy. If this hack existed in 1998, kids would have lost their god damned minds.

The basis for this hack comes from [MrCheeze], who created a ‘virus’ of sorts for the first generation of Pokemon games. Basically, given the ability to manually edit a save file, it is possible to replicate this save file over a Game Link cable. The result is a glitchy mess, but each Pokemon game has the same save file when it’s done.

Combine this virus with arbitrary code execution, and you have something remarkable. [MrCheeze] created a save file that allows you to move the truck next to the SS Anne. When the truck is moved, a Mew appears. It’s exactly what everyone was talking about over the sound of their sister’s Backstreet Boys marathon.

The new ‘Mew Truck virus’ is not as glitchy as the first attempt at a self-replicating save file. In fact, except for the music glitching for a few seconds, nothing appears abnormal about this Pokemon virus. It’s only when the Mew truck trick is attempted does something seem weird, and it’s only weird because we know it shouldn’t happen. Combine the self-replicating nature of this virus, and you have something that would have drawn the attention of Big N. This is a masterpiece of Pokemon-based arbitrary code execution and a hack that may never be equaled.

You can check out the video below.

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Surfing Like It’s 1998, The Dreamcast’s Still Got It!

March 15, 2017 by 52 Comments

If you were a keen console gamer at the end of the 1990s, the chances are you lusted after a Sega Dreamcast. Here was a console that promised to be like no other, a compact machine with built-in PowerVR 3D acceleration (heavy stuff back then!), the ability to run Windows CE in some form, and for the first time, built-in Internet connectivity. Games would no longer be plastic cartridges as they had been on previous Sega consoles, instead they would come on a proprietary DVD-like Sega disc format.

It was a shame then that the Dreamcast never really succeeded in capitalizing on its promise. Everyone was talking about the upcoming Sony Playstation 2, and disappointing Dreamcast sales led Sega to withdraw both the console, and themselves from the hardware market entirely.

There remains a hard core of Dreamcast enthusiasts though, and they continue to push the platform forward.The folks at the Dreamcast Junkyard decided to go backwards a little when they resurrected the console’s dial-up modem to see whether a platform from nearly twenty years ago could still cut it in 2017. This isn’t as easy a task as you’d imagine, because, well, who uses dial-up these days? Certainly in the UK where they’re based it’s almost unheard of. They were able to find a pay-as-you go dial-up provider though, and arming themselves with the most recent Dreamkey V3.0 browser disc were able to get online.

As you might expect, the results are hilariously awful for the most part. Modern web sites that rely on CSS fail to render or even indeed to load, but retro sites like those in the Dreamcast community appear as they should. There is a video we’ve put below the break showing the rather tortuous process, though sadly they didn’t think to load the Hackaday Retro Edition. It does however feature the rarely-seen keyboard and mouse accessories.

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Raspberry Pi Hitches Ride Inside Vintage Terminal

March 13, 2017 by 41 Comments

When a dumpster dive yielded a vintage video display terminal, [dennis1a4] knew just what to do — bring the Heathkit H19 back to life and stuff a Raspberry Pi inside.

The early days of the personal computer era were a time of great market diversity. Everyone was making stuff needed to cobble together your perfect computer, and terminals were among the most important pieces of gear. Lear Siegler, DEC, Wyse — everyone was in on the game. Even Heathkit competed with its H19 serial terminal, which would have set you back a thousand or so early-1980s dollars.

The terminal [dennis1a4] found was DOA, but he quickly determined that a bad cap was shorting out the -12VDC rail. A little extra detective work was needed to get the terminal to both echo characters locally and output them over the RS-232 port, and bam, working terminal. But then what? Raspberry Pi to the rescue! But those old school +/-12 volts swings would give a Pi a bad case of Blue Smoke Disease. After a little voltmeter poking, and through the magic of socketed driver chips, the Pi was talking right to the terminal at a screaming 9600 baud and accessing the Hackaday Retro site on the 80-by-24 mono display.

All in all, a nice hack on a piece of computer history. But just one question: Can it play Doom Flappy Bird?

Reinventing The Harwell Dekatron

March 12, 2017 by 3 Comments

A huge number of modern replicas of retro computers pass our screens here at Hackaday, and among them are an astonishing variety of technologies. Those who weren’t lucky enough to be present in the days when the building blocks of computing were coming together may have missed out on understanding gate-level operation of a computer. Put your super-powerful and super-complex systems-on-chip aside sometime and dig into the details of their distant ancestors.

Most such machines follow a very conventional architecture, so it is something of a surprise to find a project recreating a modern version of something far more obscure. The Harwell Dekatron, also known as the WITCH, can be found at the National Museum Of Computing in Bletchley, UK, and [David Anders] is building a modern all-electronic replica of it.

The original machine is currently the world’s oldest working digital computer, a hybrid electromechanical computer built at the start of the 1950s  to perform calculations for British nuclear scientists. It was retired by the end of that decade and found its way — via a technical college, a museum, and a period of storage in a council archive — to Bletchley where it was restored to working order by 2012. Its special feature is the use of dekatron discharge tubes as memory, allowing an instant visual display of its working as it happens.

[David]’s replica uses modern logic chips to replicate the building blocks of the Harwell Dekatron, and his write-up is as fascinating for that as it is for his study of the real thing in the museum. We ran into [Dave] showing off this project at the Hackaday Dallas event last year and are excited to learn of the advancements since then from his Hackaday.io page. He’s put his research and designs on GitHub, and a series of YouTube videos, the introduction to which we’ve put below the break.

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A Clock Created With Conway’s Life

March 11, 2017 by 22 Comments

Conway’s life has to be the most enduring zero-player computer game in history. Four simple cellular automaton rules have been used to create amazing simulations since the 1970’s. The latest is an entire digital clock implemented in life. StackExchange user [dim] created this simulation in response to a challenge from [Joe Z]. We have to admit that we didn’t believe it at first, but you can run it yourself by importing [dim’s] gist to the online Javascript Conway’s Life Simulator. To say this is impressive would be an understatement. We don’t know exactly how long it took [dim] to build this clock, but the challenge has been around since August of 2016.

[Dim] does a pretty good job of describing exactly how the clock works. The timebase is at the top. Below it is clock distribution and counters. After that come counters, latches, and lookup tables. Data moves around the clock in the form of gliders. P30 (aka Queen Bee) gliders to be exact. It might make things simpler to think of the glider paths as circuit traces, and the gliders themselves as clock pulses.

We couldn’t get over all the little details in this design. If you zoom way in, you can see all the lookup table patterns have been annotated, much in the way a schematic would be. For [Dim’s] next feat, we hope he takes on [Joe Z’s] Tetris challenge!

Conway’s life is like honey for hackers. We’ve seen it running on our own Hackaday Badge. We’ve even seen clocks that run the game on their display. Someone needs to implement a clock that runs the game that runs this clock. Clockception, anyone?