Wooden Game Boy Is A Challenging Intro CNC Project

November 4, 2023 by Dan Maloney 12 Comments

[Sebastian] describes himself as “a total noob” when it comes to CNC, so in an attempt to get to know his new CNC router, he chose about the most complex possible project — replicating an original Game Boy case in wood. And spoiler alert: he nailed it.

Of course, he did have a few things going for him. At least from a straight woodworking perspective, it’s hard to go wrong by choosing walnut as your material. Then again, it can be unforgiving at times, and picky about tooling, which is probably why [Sebastian] used nine different tools to get the job done. But where he upped the difficulty level was in reproducing so many of the details of the original injection-molded plastic case. There are top and bottom shells, each of which has to be milled from both sides. This makes registration tricky when the parts are flipped. Specific indexing holes were used for that, along with the old “blue tape and CA glue” fixturing trick, which seemed to work quite well. For our money, though, the best bit is the lettering on the front face, which was milled out with an engraving bit and then filled with a spritz of white spray paint. A surfacing bit then came along to knock the overspray down, leaving labels that contrast beautifully with the dark wood. Gorgeous!

It wasn’t all easy sailing, though. There are just some things plastic can do that wood can’t, like holding screw threads in small studs without splitting. So, the case had to be glued shut once the mix of salvaged and new components went in. Still, it looks fabulous, and [Sebastian] says what we see in the video below is the one and only piece. Pretty sweet for the first try. Surprisingly, it doesn’t seem as if we’ve seen a wooden Game Boy before — a wooden NES, sure, but not a Game Boy.

Continue reading “Wooden Game Boy Is A Challenging Intro CNC Project” →

Machine Teaches Morse Code

November 3, 2023 by Al Williams 4 Comments

If you are a ham radio operator of a certain age, you probably remember ads for “The Instructograph,” a mechanical device for learning Morse code. [Our Own Devices] has an ancient specimen of the machine and shows us how it works in the video below. The machine is a model of simplicity. You wind up a spring-driven motor like you would for an old record player or music box. A slider sets the playback rate, and paper tape starts to spin.

The paper tape looks like computer tape, but since it only has literal long and short notches, it has two distinct sides. When you learned one set of messages, you could flip the tape over and get more practice that way. How did the machine read the paper tape? With a mechanical contact. Literally, if the paper had a hole in it, you made the circuit. If it didn’t, the circuit was broken. A buzzer and batteries or some other kind of sounder was all you needed.

The company was in business for 50 years. The newer versions had more electronics, but they always used the paper tape mechanism to store the code practice sessions. A 1962 ad noted that the machine could play back the tapes from three words a minute up to 40. You could buy or rent the machine, and we always assumed it was pretty pricey for its day. Around 1965, a new unit would cost $53 but did not include a headset or a key. So that was actually more reasonable than we expected. In 1965, a brand-name clock radio cost about $50, so it wasn’t any more than that.

Everyone has their own favorite method for learning code, especially [Ludwig Koch]. At least you don’t have to learn Alex-style.

Continue reading “Machine Teaches Morse Code” →

Partial Relay-Based Calculator Puts The Click Where It Counts

November 3, 2023 by Dan Maloney 15 Comments

It looks like [Michal Zalewski] is raising the next generation the right way. First, his eldest son asks for help building a one-bit computer from discrete transistors. Not to be left behind, his little brother then asked for help with an even more retro project, which resulted in this partially relay-based calculator. Maybe there is some hope for the future.

Now, purists will no doubt notice the ATmega64 microcontroller sitting in the middle of the main PCB on this project and cry “Foul!” But perfect is the enemy of done, and as [Michal] explains, at $6 a pop for the Omron relays he and his son chose, there’s only so far you can go with relay logic before you’re taking out a second mortgage. So the relays are limited to the ALU of the calculator, along with the drivers for the six seven-segment LED displays. The microcontroller is just there for housekeeping functions like scanning the keyboard and decoding digits. All the actual calculations are in the relay logic, not silicon. And we’d be remiss not to praise his son’s stylistic choices for this design — that it uses relays with clear covers, and that it has ~~single-sided~~ PCBs with curvy, ~~hand-drawn traces~~ traces that look hand-drawn on old-school yellow substrate. [Michal]’s heart must swell with pride to have fathered someone with such exquisite taste.

For his part, [Mikal] did some really good documentation for this build, including excellent descriptions of Boolean math with half- and full-adders and how relays are used to create the basic logic gates that comprise them. The calculator itself is still a work in progress, with microcontroller code still in development, but it’s working enough that you can enjoy the display driver’s clickiness in the video below. If that doesn’t do it for you, we’ve got other relay calculators to scratch that click itch. Continue reading “Partial Relay-Based Calculator Puts The Click Where It Counts” →

Random Number Generator Is A Blast From The Past

November 2, 2023 by Tom Nardi 16 Comments

Hackers love random numbers, or more accurately, the pursuit of them. It turns out that computers are so good at following our exacting instructions that they are largely incapable of doing anything that would fit the strict definition of randomness — which has lead to some elaborate methods of generating the unexpected.

Admittedly, the SB42 Random Number Generator built by [Simon Boak] isn’t exactly something you’d be using for cryptography. The method used to generate the digits, a pair of 555 timers sending pulses through linear-feedback shift registers, would at best be considered pseudo-random. Plus the only way of getting the digits out of the machine is by extracting them from the Nixie tubes with your Mark I Eyeballs. But it absolutely excels at the secondary reason many hackers like to build their own randomness rigs — it looks awesome.

Externally, it absolutely nails the look of a piece of vintage DIY year. Down to the classic white-on-black label tape. But open up the hood, and you’re treated to a real rarity these days: wirewrap construction. In an era where you can get PCBs made and shipped to your door for literally pennies, [Simon] is out there keeping the old ways alive. It doesn’t just look the part either. Unlike most modern projects we see, there isn’t a multi-core microcontroller behind the scenes doing all the work, it’s logic gates all the way down.

This isn’t the first random-ish number generator that we’ve seen use shift registers. But if you’re looking for something that might actually pass some randomness checks, and don’t mind working with something a bit spicy, you could check out some of the previous devices we’ve covered that used radioactive decay as an entropy source.

Continue reading “Random Number Generator Is A Blast From The Past” →

Make Your Own 1970s Magnetic Stripe Cards

October 25, 2023 by Jenny List 8 Comments

We’re now all used to near-limitless storage on flash and other semiconductor technologies, but there was a time when persistent storage was considerably less easy to achieve. A 1970s programmable calculator from Sharp approached the problem with magnetic strips on special cards, and since [Menadue] has one with no cards, he set about making his own.

These cards are a little different to the credit-card-style cards we might expect, instead they’re a narrow strip with a magnetic stripe down their centre. The unusual feature can be found at the edge, where a row of perforations provide the equivalent of a clock line.

The newly manufactured cards have the clock slots machined along their edges, and then the magnetic part formed from self-adhesive magnetic strip. This last thing is a product we were not aware existed, and can think of plenty of possible applications.

The result as you can see in the video below the break are some cards with variable reliability. There’s a suggestion that white cards might work less well with the infrared light used in the clock detector, also a suspicion the low batteries make reading less easy, but still he’s able to retrieve a stored program. An extinct medium is revived.

Longtime readers will know we’ve spent time in calculator country before.

Continue reading “Make Your Own 1970s Magnetic Stripe Cards” →

Converting A Polaroid SX70 Camera To Use 600 Film

October 20, 2023 by Lewin Day 4 Comments

These days, it’s possible to buy a number of different Polaroid instant cameras new off the shelf. That’s largely thanks to the retro resurgence that has buoyed interest in everything from vinyl records to analog synthesizers. However, if you’re truly old-school, you might still be rocking a vintage Polaroid SX-70 camera. Thankfully, there’s a way to convert these old rigs to work properly with the more popular modern 600 film.

The interesting thing about the SX-70 camera design is that its shutter speed and aperture setting are essentially linked together as the aperture and shutter assembly are combined into one unit with a variable tear-drop shaped opening. Thus, the timing of the shutter opening and closing and the extent to which it opens are what determines exposure and aperture.

Thankfully, [Jake Bright] has learned a lot about these unique cameras and exactly how this complex system operates. He shares his tips on firstly restoring the camera to factory-grade operation, and then the methods in which they may be converted to work with modern film. Fundamentally, it’s about changing capacitors or resistors to change the shutter/aperture timing. However, do it blindly and you’ll have little success. You first need to understand the camera’s mechanics, pneumatics, and its “Electric Eye” control system before you can get things dialed in just so.

We’ve seldom seen such a great deep dive into a camera outside of full-fat engineering documentation. [Jake] should be commended on his deep understanding and command of these fine instant cameras from yesteryear. May the Polaroid picture never die. Video after the break. Continue reading “Converting A Polaroid SX70 Camera To Use 600 Film” →

Spinning Up A New Laundry Monitor

October 20, 2023 by Kristina Panos 17 Comments

For all that modern washers and dryers do, they don’t let you know when they’re finished. Or they do, but it’s only a short victory song that plays once and can be easy to miss. What most of us need is a gentle reminder that there’s damp laundry festering in the washer, or fresh laundry in the dryer getting wrinkly.

This laundry monitor from [Sparks and Code] is version 2.0. The first version was working fine, but it was based on vibration (or lack thereof). Fast forward a few years, and [Sparks and Code] got a modern pair that’s so finely tuned, it doesn’t produce enough vibration to register. Back to the drawing board [Sparks and Code] went, and eventually came up with version 2.0.

Now, [Sparks and Code] is detecting whether the machines are on using a pair of split-core transformers to monitor power at the breaker box. With these, you just run the wire through the hole, and it gives the relative mV value going through the wire on a 3.5mm cable. Those cables are connected to an ESP32 inside the 3D-printed box, which is mounted above the cabinet door. Since [Sparks and Code] already has home assistants all over the house, it was easy to integrate and have them all play the message ‘please flip the laundry’.

Once this project was all buttoned up, they thought of one issue — the self-cleaning cycle. Since it takes about four hours, they like to run it overnight. You can see the problem here — no one wants to hear Alexa at 3AM. Fortunately, [Sparks and Code] was able to adjust the Python script to ignore these events. Be sure to check out the build video after the break.

If only the dryer could empty itself and fold the clothes. Oh wait, there’s a robot for that.

Continue reading “Spinning Up A New Laundry Monitor” →