Beats An Extension Cord

June 22, 2018 by Brian McEvoy 18 Comments

What does your benchtop power supply have that [Pete Marchetto]’s does not? Answer: an extension cord draped across the floor. How often have you said to yourself, “I just need to energize this doodad for a couple seconds,” then you start daisy chaining every battery in the junk drawer to reach the necessary voltage? It is not uncommon to see battery packs with a single voltage output, but [Pete] could not find an adjustable one, so he built his own and put it on Tindie.

Presumably, the internals are not going to surprise anyone: an 18650 battery, charging circuit, a voltage converter, display, adjustment knob, and a dedicated USB charging port. The complexity is not what intrigues us, it is the fact that we do not see more of them and still wind up taping nine-volt batteries together. [Editor’s note: we use one made from an old laptop battery.]

This should not replace your benchtop power supply, it does not have the bells and whistles, like current regulation, but a mobile source of arbitrary voltage does most of the job most of the time. And it’s what this build hasn’t got (a cord) that makes it most useful.

There’s RC2014 Life In The TMS9918A Display Chip Yet

June 22, 2018 by Jenny List 30 Comments

One of the outliers in the home computer wars of the early 1980s was the Texas Instruments TI99/4A. It may not have had the games library of its rivals and its TMS9900 processor may not have set the world on fire with its registers-in-RAM architecture, but its range of support chips included one whose derivatives would go on to delight subsequent generations. If you had an MSX or one of the 8 or 16-bit Sega consoles, the TMS9918A graphics chip provided the architecture that sat behind Sonic in his adventures.

A few decades later, there is still significant interest in this classic chip. [J.B. Langston] has an RC2014 retrocomputer, and wishing to play MSX demos upon it, has created a TMS9918A-based graphics card for the RC2014 bus. The success of the board hinges upon a circuit showing how to interface the 9918A to SRAM, and since it is mapped to the same ports as its MSX equivalent it should in theory be compatible with Z80 demos written for that platform. He’s already achieved some success with that aim, as can be demonstrated by the video we’ve placed below the break of the Bold MSX demo running on an RC2014.

The RC2014 has gained a significant following in the retrocomputer scene, and has appeared here many times. We reviewed an early model in 2016. Surprisingly though the TMS9918A has only appeared here once, as part of a homebrew 6809-based system.

Continue reading “There’s RC2014 Life In The TMS9918A Display Chip Yet” →

Linux Fu: The Great Power Of Make

June 22, 2018 by Al Williams 76 Comments

Over the years, Linux (well, the operating system that is commonly known as Linux which is the Linux kernel and the GNU tools) has become much more complicated than its Unix roots. That’s inevitable, of course. However, it means old-timers get to slowly grow into new features while new people have to learn all in one gulp. A good example of this is how software is typically built on a Linux system. Fundamentally, most projects use make — a program that tries to be smart about running compiles. This was especially important when your 100 MHz CPU connected to a very slow disk drive would take a day to build a significant piece of software. On the face of it, make is pretty simple. But today, looking at a typical makefile will give you a headache, and many projects use an abstraction over make that further obscures things.

In this article, I want to show you how simple a makefile can be. If you can build a simple makefile, you’ll find they have more uses than you might think. I’m going to focus on C, but only because that’s sort of the least common denominator. A make file can build just about anything from a shell prompt.

Continue reading “Linux Fu: The Great Power Of Make” →

When Vortex Rings Collide

June 22, 2018 by Adam Fabio 38 Comments

Intrigued by a grainy video from 1992, [Destin] from Smarter Every Day decided to jump in and fund his own research into the strange phenomenon of vortex ring collisions.

This hack started with a scientific publication and a video from back in 1992. The paper, written by Dr. T T Lim and TB Nichols, illustrated what happens when two vortex rings collide perfectly head-on. The rings collide and spread out forming a thin membrane. Then smaller rings form at a 90-degree angle to the original collision. It’s a beautiful effect when created with multicolored dye in water. But what causes it? There are theories about the fluid mechanics involved, but not much research has gone on since Dr. Lim’s paper.

[Destin] wanted to find out more about the effect, and get some video of it. Being the guy behind Smarter Every Day, he had the high-speed photography equipment and the funds to make that happen. Little did he know that this passion project would take four years to complete.

The initial prototype was built as part of a senior design project by a group of college students. While they did show the phenomenon, it was only barely visible, and not easily repeatable. [Destin] then got an engineer to design and build the experiment apparatus with him. It took numerous prototypes and changes, and years of development.

The final “vortex cannons” are driven by a computer controlled pneumatic cylinder which ensures both cannons get a perfect pulse of air. The air pushes a membrane which moves the dye and water out through an orifice. It’s a very finicky process, but when everything goes right, the result is a perfect collision. Just as in Dr. Lim’s video, the vortexes crash into each other, then form a ring on smaller vortexes.

Destin didn’t stop there. He’s made his data public, in the form of high-speed video – nearly 12 hours worth when played at normal speed. The hope is that researchers and engineers will now have enough information to better understand this phenomenon.

You can check out the videos after the break. If you’re a Smarter Every Day fan, we’ve covered [Destin’s] work in the past, including his backwards brain bike and his work with magnets.

Continue reading “When Vortex Rings Collide” →

Analog Meters Become A Clock For Father’s Day

June 22, 2018 by Dan Maloney 8 Comments

Around Father’s Day each year, we usually see a small spate of dad-oriented projects. Some are projects by dads or granddads for the kids, while others are gifts for the big guy. This analog meter clock fits the latter category, with the extra bonus of recognizing and honoring the influence [Micheal Teeuw]’s father had on him with all things technological.

[Michael] had been mulling over a voltmeter clock, where hours, minutes and seconds are displayed on moving coil meters, for a while. A trio of analog meters from Ali Express would lend just the right look to the project, but being 200-volt AC meters, they required a little modification. [Michael] removed the rectifying diode and filtering capacitor inside the movement, and replaced the current-limiting resistor with a smaller value to get 5 volts full-range deflection on the meters. Adobe Illustrator helped with replacing the original scales with time scales, and LEDs were added to the meters for backlighting. A TinyRTC keeps time and generates the three PWM signals to drive the meters. Each meter is mounted in its own 3D-printed case, the three of which are linked together into one sleek console. We love the look, which reminds us of an instrument cluster in an airplane cockpit.

Bravo to [Michael’s Dad] for getting his son into the tinkering arts, and cheers to [Michael] on the nice build. We like seeing new uses for old meters, like these server performance monitoring meters.

[via r/DIY]

[Festo]’s Underwater Robot Uses Body-Length Fins

June 21, 2018 by Steven Dufresne 17 Comments

[Festo] have come up with yet another amazing robot, a swimming one this time with an elegant propulsion mechanism. They call it the BionicFinWave. Two fins on either side almost a body-length long create a wave which pushes water backward, making the robot move forward. It’s modeled after such fish as the cuttlefish and the Nile perch.

What was their elegant solution for making the fins undulate? Nine lever arms are attached to each fin. Those lever arms are controlled by two crankshafts which extend from the front of the body to the rear, one for each side. A servo motor then turns each crankshaft. Since the crankshafts are independent, that means each fin operates independently. This allows for turning by having one fin move faster than the other. A third motor in the head flexes the body, causing the robot to swim up or down.

There’s also a pressure sensor and an ultrasonic sensor in the head for depth control and avoiding objects and walls. While these allow it to swim autonomously in its acrylic, tubular track, there is wireless communication for recording sensor data. Watch it in the video below as it effortlessly swims around its track.

[Festo] has created a lot of these marvels over the years. We’ve previously covered their bionic hopping kangaroo (we kid you not), their robot ants with circuitry printed on their exoskeleton, and perhaps the most realistic flapping robotic bird ever made.

Continue reading “[Festo]’s Underwater Robot Uses Body-Length Fins” →

Computers Go Hollywood

June 21, 2018 by Al Williams 5 Comments

Have you ever been watching a TV show or a movie and spotted a familiar computer? [James Carter] did and he created a website to help you identify which old computers appear in TV shows and movies. We came across this when researching another post about an old computer and wondered if it was any old movies. It wasn’t.

You can search by computer or by title. There are also ratings about how visible, realistic, and important the computer is for each item. The database only contains fictional works, not commercials or documentaries. The oldest entry we could find was 1950’s Destination Moon which starred a GE Differential Analyzer. Well, also John Archer, we suppose. We assume GE had a good agent as the same computer showed up in Earth vs. the Flying Saucers (1956) and When Worlds Collide (1951). You can see a clip of the computer’s appearance in Earth vs. the Flying Saucers, below.

Continue reading “Computers Go Hollywood” →