Minivac 601 Replica Gets A Custom Motorized Rotary Switch

July 13, 2019 by 2 Comments

One of the joys of electronics as a hobby is how easy it is to get parts. Literally millions of parts are available from thousands of suppliers and hundreds of distributors, and everyone competes with each other to make it as easy as possible to put together an order from a BoM. If you need it, somebody probably has it.

But what do you do when you need a part that doesn’t exist anymore, and even when it did was only produced in small numbers? Easy – you create it yourself. That’s just what [Mike Gardi] did with this unique motorized rotary switch he needed to complete his replica of a 1960s computer trainer. We covered his build of the Minivac 601, a trainer from the early computer age that let experimenters learn the ropes of basic digital logic. It used mostly relays, lamps, and switches connected by jumpers, but it had one critical component – a rotary control that was used for input and, with the help of a motor, as an output indicator.

[Mike]’s version of the switch is as faithful to the original as possible, at least in terms of looks. The parts are mostly 3D-printed, with 16 reed switches embedded in the walls and magnets placed in the rotor. The motor to operate the rotor is a simple gear motor mounted to a hinged bracket; when the rotor needs to move, a solenoid pulls the motor’s friction drive wheel up against the rotor.

The unique control slots right into the Minivac replica and really completes the look and feel. Hats off to [Mike] for a delightful replica of a lost bit of computer history and the dedication to see it through to completion.

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A Wedding Gift Fit For A Hardware Hacker

July 13, 2019 by 7 Comments

If you read Hackaday on a regular basis, there are some names you will have seen more than once. People who continually produce fascinating and inventive projects that amaze and delight us, and who always keep us coming back for more. One such hacker is [Jeroen Domburg], perhaps better known in these pages by the handle [Sprite_TM], who has never failed to delight us in this respect.

Today is a special day for [Jeroen] for it is his wedding day, and his friend [Maarten Tromp] has decided to surprise him and his wife [Mingming] with a special gift. At first sight it is simply a pair of blinky badges in the shape of a bride and groom, but closer examination reveals much more. The PCBs are studded with WS2812 addressable LEDs controlled by an ESP32 module and powered by a small LiPo battery, and the clever part lies in the software. The two badges communicate via Bluetooth, allowing them to both synchronise their flashing and flash ever faster as the couple come closer to each other.

The write-up is an interesting tale of the tribulations of designing a badge, from which we take away that buying cheap LEDs may be a false economy. A surprise was that the black-cased and white-cased versions of the LEDs had different timings, and they proved prone to failure.

We wish the happy couple all the best, thank [Sprite_TM] for all he has given us over the years, and look forward to seeing his future projects.

3D Printing An Old-School Coherer

July 13, 2019 by 29 Comments

Coherers were devices used in some of the very earliest radio experiments in the 19th century. Consisting of a tube filled with metal filings with an electrode at each end, the coherer would begin to conduct when in the presence of radio frequency energy. Physically tapping the device would then loosen the filings again, and the device was once again ready to detect incoming signals. [hombremagnetico] has designed a basic 3D printed version of the device, and has been experimenting with it at home.

It’s a remarkably simple build, with the 3D printed components being a series of three brackets that combine to hold a small piece of plastic tube. This tube is filled with iron filings, and electrodes are inserted from either end. Super glue is used to seal the tube, and the coherer is complete.

The coherer can easily be tested by measuring the resistance between the two electrodes, and firing a piezo igniter near the tube. When the piezo igniter sparks, the coherer rapidly becomes conductive, and can be restored to a non-conductive state, or de-cohered, by tapping the tube.

Coherers and spark-gap sets are fun to experiment with, but be sure you have the proper approvals first. Video after the break.

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Simple Simon Says Looks Sharp

July 12, 2019 by 4 Comments

Simon was a popular toy, launching at the very end of the 1970s, and cribbed from earlier work by Atari with their game Touch Me. The gameplay is simple, and while we suspect it won’t last quite as long as the several thousand years we’ve so far had chess, it’s still around today. [DIY Machines] decided to bust out the 3D printer and whip up their own version.

Simon has long served as a great test project to get to grips with various maker skills, and this build is no exception. An Arduino Nano runs the show, and gets an OLED display to display the current level. Large glowing arcade buttons serve as the control, with their lights flashed as per the original game. Sound is courtesy of a simple buzzer.

It’s a build that doesn’t do anything wild, but presents very well. This is down to the smoothly finished and nicely designed case, as well as the choice of quality human interface components. Everyone loves mashing arcade buttons, and that’s what they’re built for – so they’re always a safe choice.

We’ve seen a lot of straight-down-the-lines Simon projects, but this DDR-ified version is a fun twist on the standard form. Video after the break.

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You Are Probably Using NASA Technology

July 12, 2019 by 50 Comments

You often hear people — especially non-hacker types — complain that money spent on space travel would be better off spent here on Earth. Of course that ignores one big factor, that space programs have resulted in a host of spin off technologies, many of which you use every day. JPL has an infographic that covers twenty things we wouldn’t have without space travel, and while it could be said that some of these things might have been invented anyway it would doubtless have taken much longer without the necessity and the income from space programs. If you want more detail, Tech Briefs has an interesting interview on the subject of what tech spun off the Apollo program.

Some of the inventions are pretty obvious, and others are more refinements of things that already existed. We all knew NASA pioneered freeze drying for food, for instance. However, some of them are pretty surprising. For example, according to the infographic, NASA asking Black and Decker to develop a moon sample collector led to the Dust Buster.

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Keep Pesky Cats At Bay With A Machine-Learning Turret Gun

July 12, 2019 by 32 Comments

It doesn’t take long after getting a cat in your life to learn who’s really in charge. Cats do pretty much what they want to do, when they want to do it, and for exactly as long as it suits them. Any correlation with your wants and needs is strictly coincidental, and subject to change without notice, because cats.

[Alvaro Ferrán Cifuentes] almost learned this the hard way, when his cat developed a habit of exploring the countertops in his kitchen and nearly turned on the cooktop while he was away. To modulate this behavior, [Alvaro] built this AI Nerf turret gun. The business end of the system is just a gun mounted on a pan-tilt base made from 3D-printed parts and a pair of hobby servos. A webcam rides atop the gun and feeds into a PC running software that implements the YOLO3 localization algorithm. The program finds the cat, tracks its centroid, and swivels the gun to match it. If the cat stays in the no-go zone above the countertop for three seconds, he gets a dart in his general direction. [Alvaro] found that the noise of the gun tracking him was enough to send the cat scampering, proving that cats are capable of learning as long as it suits them.

We like this build and appreciate any attempt to bring order to the chaos a cat can bring to a household. It also puts us in mind of [Matthias Wandel]’s recent attempt to keep warm in his shop, although his detection algorithm was much simpler.

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Photochromic Screen Makes For An Interesting Clock

July 12, 2019 by 4 Comments

The clock project will always be a hacker staple, giving the builder a great way to build something useful and express their individual flair. [Mosivers] was undertaking a build of their own and decided to go for a twist, creating a timepiece with a photochromic display.

The clock uses an Arduino Nano to run the show, hooked up to a 4-digit, 7-segment display that is custom built on protoboard. By using ultraviolet LEDs and placing them behind a reactive screen, it’s possible to create a unique display. The clock can be used with two different screens: a photochromic display created with UV-reactive PLA filament that turns purple when excited by UV light, and a glow-in-the-dark screen for night use.

It’s a fun twist on a simple clock design, and the purple-on-white digits are sure to raise some eyebrows among curious onlookers. Photochromic materials are fun to play with, and can make eggs and glass much more visually interesting. Video after the break.

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