Int 1777, Georg Lichtenberg found that discharging high voltage on an insulating surface covered with a powder, a fractal-like image appears, sometimes known as a lightning tree. Incidentally, this is a crude form of xerography, the principle that lets copiers and laser printers operate.
[PaulGetson] had a high voltage power source from his Jacob’s ladder experiments and decide to see if he could create Lichtenberg figures. Turns out, he could.
There was a time when making a high voltage project like a Jacob’s ladder took time to build or scrounge some kind of high voltage circuit. The neon sign transformer, Marx generator, or voltage multiplier was the hard part of the project. But nowadays you can get cheap high voltage modules that are quite inexpensive. [PaulGetson] picked up one for under $20 and turned it into a quick and easy Jacob’s ladder.
Honestly, once you have high voltage, making a Jacob’s ladder is pretty simple. [Paul] used a cheap plastic box, some coat hanger wire, and some stainless steel bolts.
[Justin] had been trying to find a good tube amp for years, but all the best examples were either expensive or a complete basket case. Instead of buying a vintage stereo tube amp, he decided to build his own using the guts of a Heathkit AA-100, a popular tube amp from the 60s and 70s that doesn’t have a great reputation for sound quality.
This project was based on an earlier project from a decade ago that replicated the very popular Dynaco ST-70 tube amp from parts taken from the Heathkit AA-100. The schematic for this conversion was readily available on the usual tube head message boards, and a few PCBs were available for the input stage.
With the schematic in hand, the next thing for [Justin] to do was get a nice enclosure. High quality tube amps are valued as much for their appearance as they are for their sound quality, and after giving his father-in-law a few sketches, a cherry hardwood chassis stained in a beautiful golden brown appeared on [Justin]’s workbench.
The big iron for this new tube amp was taken directly from the old Heathkit, and a few hours in front of a mill netted [Justin] a chassis panel drilled out for the transformers and tube sockets. The rest of the project was a bit of assembly, point-to-point wiring, and wire management giving [Justin] a fantastic amplifier that will last for another fifty years until someone decides to reuse the transformers.
[Andrew Milkovich] was inspired build his own Super Nintendo cartridge reader based on a device we covered an eternity (in internet years) ago. The device mounts a real cartridge as a USB mass storage device, allowing you to play your games using an emulator directly from the cart.
This uses a Teensy++ 2.0 at its core. [Andrew] had to desolder the EEPROM pins from the SNES cartridge and reverse engineer the pinouts himself, but the end result was a device that could successfully read the cartridge without erasing it, no small accomplishment. The finished cartridge reader is build on some protoboard and we’d like to complement [Andrew] on his jumper routing on the underside of that board.
Of course, the experience of any console is just not the same without the original controller. So [Andrew] went a step further and made his own SNES controller to USB converter. This had the venerable Atmel ATmega328 at its core, and can be used separate from the cartridge reader if desired.
We are fortunate to live in an age of commoditized high-power computer hardware and driver abstraction, in which most up-to-date computers have the ability to do more or less anything that requires keeping up with the attention of a human without breaking a sweat. Processors are very fast, memory is plentiful, and 3D graphics acceleration is both speedy and ubiquitous.
Thirty years ago it was a different matter on the desktop. Even the fastest processors of the day would struggle to perform on their own all the tasks demanded of them by a 1980s teenager who had gained a taste for arcade games. The manufacturers rose to this challenge by surrounding whichever CPU they had chosen with custom co-processors, ASICs that would take away the heavy lifting associated with 2D graphics acceleration, or audio and music synthesis.
One of the 1980s objects of computing desire was the Atari ST, featuring a Motorola 68000 processor, a then-astounding 512k of RAM, a GUI OS, high-res colour graphics, and 3.5″ floppy drive storage. Were you to open up the case of your ST you’d have found those ASICs we mentioned as being responsible for its impressive spec.
Jumping forward three decades, [Christian Zietz] found that there was frustratingly little information on the ST ASIC internal workings. Since a trove of backed-up data became available when Atari closed down he thought it would be worth digging through it to see what he could find. His write-up is a story of detective work in ancient OS and backup software archaeology, but it paid off as he found schematics for not only an ASIC from an unreleased Atari product but for the early ST ASICs he was looking for. He found hundreds of pages of schematics and timing diagrams which will surely take the efforts of many Atari enthusiasts to fully understand, and best of all he thinks there are more to be unlocked.
We’ve covered a lot of Atari stories over the years, but many of them have related to their other products such as the iconic 2600 console. We have brought you news of an open-source ST on an FPGA though, and more recently the restoration of an ST that had had a hard life. The title of this piece refers to the fate of Atari’s huge unsold stocks of 2600 console cartridges, such a disastrous marketing failure that unsold cartridges were taken to a New Mexico landfill site in 1983 and buried. We reported on the 2013 exhumation of these video gaming relics.
A tip of the hat to Hacker News for bringing this to our attention.
Atari ST image, Bill Bertram (CC-BY-2.5) via Wikimedia Commons.
If there was one book that describes what it means to be in the trenches of a cutting edge design, that book is The Soul Of a New Machine. Tracy Kidder’s Pulitzer prize-winning book has been an inspiration to thousands over the years.
Soul is the story of the creation of the Data General Eclipse MV/8000, code-named Eagle. Eagle was Data General’s first 32-bit minicomputer. If you’re not a retrocomputing aficionado, minicomputers were a major industry back in the 70’s and 80’s. Starting in 1964 with the Digital Equipment Corporation (DEC) PDP-8, minis provided a low-cost means for companies to get a computer. The only other option was a huge mainframe from companies like IBM. Minicomputers chugged along until the 1990s when microprocessor-based PCs and workstations passed them by. The market, and the industry evaporated.
Today, more than 30 years later, minicomputers are all but forgotten. Data General itself is long gone, purchased by EMC in 1999. DG’s mark on the landscape has all but been erased by the swiftly moving sands of technical progress. All except for the snapshot Kidder set down in Soul.
The technical side of designing a new computer is just one part of this book. The Soul of a New Machine is three stories: the story of the engineers, the story of the managers, and the story of the machine they built. For this reason, the book has found itself on the reading list of engineering schools and management institutes alike.
The thing that makes this book appeal to the masses is Kidder’s uncanny ability to explain incredibly complex topics in layman’s terms. He manages to explain the inner workings of a 32-bit CPU, all the way down to the level of microcode. He delves into Programmable Array Logic (PALs), forerunners of the CPLD and FPGA devices you read about on our pages today. PALs were a hot new technology back in the late 70’s. They allowed the Eagle team to make changes quickly — without pulling out their wire wrapping tools.
Kidder manages to explain these things in a way that doesn’t leave the average Joe scratching their head, yet doesn’t bore the technically savvy. If he ever decides to stop writing non-fiction, Tracy Kidder would have a career writing user manuals.
The Soul of a New Machine starts in a very unlikely place – on the deck of a sailing ship during a rough storm. The scene is our introduction to the star of the book – Tom West, a manager at Data General. West is multifaceted and enigmatic to say the least. A folk guitarist who was inspired to work on electronics by the Apollo program. He was a few years too late for NASA though. Eventually he found himself travelling the world building and adjusting incredibly accurate clocks at astronomical observatories for the Smithsonian. This meandering path eventually led him to DG, where he was hired as a computer engineer and quickly worked his way up the ranks.
Continue reading “Books You Should Read: The Soul Of A New Machine”
Ever noticed that a rubber band gets warmer when it’s stretched? The bands also get cooler when allowed to snap back to relaxed length? [Ben Krasnow] noticed, and he built a rubber band cooled refrigerator to demonstrate the concept. The idea of stretching a rubber band to make it hotter, then releasing it to make it cooler seems a bit counter intuitive. Normally when things get smaller (like a gas being compressed) they get hotter. When pressure is released the gas gets cooler. Rubber bands do the exact opposite. Stretching a rubber band makes it hot. Releasing the stretched band causes it to get cooler.
No, the second law of thermodynamics isn’t in jeopardy. The secret is in the molecular structure of rubber bands. The bands are made of long polymer chains. A relaxed rubber band’s chains are a tangled mess. Stretching the band causes the chains to untangle and line up in an orderly fashion. By stretching the band you are decreasing its entropy. The energy of the molecules in the band don’t change, but entropy does. All the work one does to st
retch the band has to go somewhere, and that somewhere is heat. This is all an example of entropic force. For a physics model of what’s going on, check out ideal chains. If you’re confused, watch the video. [Ben] does a better job of explaining entropic force visually than we can with text.
To test this phenomenon out, [Ben] first built a wheel with rubber bands as spokes. Placing the wheel in front of a heater caused it to slowly rotate. [Ben] then reversed the process by building a refrigerator. He modeled his parts in solidworks, then cut parts with his Shaper handheld CNC. The fridge itself consists of an offset wheel of rubber bands. The bands are stretched outside the fridge, and released inside. Two fans help transfer the thermal energy from the bands to the air. The whole thing is hand cranked, so this would make a perfect museum or educational demonstration. Cranking the fridge for 5 minutes did get the air inside a couple of degrees cooler. Rubber is never going to displace standard refrigerants, but this is a great demo of the principles of entropic force.
For more thermodynamic fun, check out [Al Williams] recent article about building a DIY heat pipe.
