Author: Dan Maloney

2988 Articles

POV Digital Clock Is The Literal Sands Of Time

May 9, 2024 by 8 Comments

Sand has been used to keep track of the passage of time since antiquity. But using sand to make a persistence of vision digital clock (English translation) is something altogether new. And it’s pretty cool, too.

The idea behind the timepiece that [Álvaro Gómez Giménez] built is pretty simple drop a tiny slug of fine sand from a hopper and light it up at just the right point in its fall. Do that rapidly enough and you can build up an image of the digits you want to display. Simple in concept, but the devil is in the details. Sand isn’t the easiest material to control, so most of the work went into designing hoppers with solenoid-controlled gates to dispense well-formed slugs of sand at just the right moment. Each digit of the clock has four of these gates in parallel, and controlling when the 16 gates open and close and when the LEDs are turned on is the work of a PIC18F4550 microcontroller.

The build has a lot of intricate parts, some 3D printed and some machined, but all very carefully crafted. We particularly like the big block of clear plastic that was milled into a mount for the main PCB; the translucent finish on the milled surfaces makes a fantastic diffuser for the 96 white LEDs. The clock actually works a lot better than we expected, with the digits easy to make out against a dark background. Check it out in the video below.

Between the noise of 16 solenoids and the sand getting everywhere, we’d imagine it wouldn’t be a lot of fun to have on a desk or nightstand, but the execution is top-notch, and an interesting and unusual concept we haven’t seen before. Sure, we’ve seen sandwriting, but that’s totally different. Continue reading “POV Digital Clock Is The Literal Sands Of Time” →

Matchbox Transceiver Pushes The Spy Radio Concept To Its Limits

May 9, 2024 by 19 Comments

The Altoids tin has long been the enclosure of choice for those seeking to show off their miniaturization chops. This is especially true for amateur radio homebrewers — you really have to know what you’re doing to stuff a complete radio in a tiny tin. But when you can build an entire 80-meter transceiver in a matchbox, that’s a whole other level of DIY prowess.

It’s no surprise that this one comes to us from [Helge Fykse (LA6NCA)], who has used the aforementioned Altoids tin to build an impressive range of “spy radios” in both vacuum tube and solid-state versions. He wisely chose solid-state for the matchbox version of the transceiver, using just three transistors and a dual op-amp in a DIP-8 package. There’s also an RF mixer in an SMD package; [Helge] doesn’t specify the parts, but it looks like it might be from Mini-Circuits. Everything is mounted dead bug style on tiny pieces of copper-clad board that get soldered to a board just the right size to fit in a matchbox.

A 9 volt battery, riding in a separate matchbox, powers the rig. As do the earbud and tiny Morse key. That doesn’t detract from the build at all, and neither does the fact that the half-wave dipole antenna is disguised as a roll of fishing line. [Helge]’s demo of the radio is impressive too. The antenna is set up very low to the ground to take advantage of near vertical incidence skywave (NVIS) propagation, which tends to direct signals straight up into the ionosphere and scatter them almost directly back down. This allows for medium-range contacts like [Helge]’s 239 km contact in the video below.

Banging out Morse with no sidetone was a challenge, but it’s a small price to pay for such a cool build. We’re not sure how much smaller [Helge] can go, but we’re eager to see him try.

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Mostly Printed CNC Gets A Few Upgrades

May 7, 2024 by 8 Comments

The Mostly Printed CNC is famous for two things. First, being made mostly from 3D printed parts and commonly available steel tubing. Second, because of the materials used, its rigidity isn’t fantastic. But any CNC router is better than no CNC router, and [Alan Reiner]’s “Mostly Mostly Printed CNC” upgrades the base MPCNC into a much more capable unit.

MPCNC purists may want to look away, as the video below shows [Alan] committing the heresy of adding linear rails to his machine. The rails were sourced from VEVOR and at less than $100 for 10 meters, it must have been hard to resist. The rigidity wasn’t amazing — witness the horrific chatter at around the 5:15 mark — but [Alan] sorted that out with some aluminum extrusion and printed adapters.

Those upgrades alone were enough to let [Alan] dive into some aluminum cutting, but he also wanted to address another gripe with his base build: the Z-axis backlash. The fix there was to add another lead screw nut on an adjustable carrier. By tweaking the relative angles of the two opposed nuts, almost all of the backlash was taken up. [Alan] also replaced the motor coupling on the Z axis with a Lovejoy-style coupler, to remove as much axial compliance as possible.

Along with the motion control mods, [Alan] improved work holding and added an enclosure to tame the chip beast, along with some upgrades to the control electronics. The results are pretty good and appear well worth the modest added expense. Maybe a wireless controller can be next on the upgrade list?

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RepTrap Keeps Watch Over Our Cold-Blooded Friends

May 7, 2024 by 1 Comment

Wait a second, read that title again. This isn’t a throwback 3D printing project at all. That’s “RepTrap” as in reptile trap, and it’s a pretty clever way to study our cold-blooded friends in their natural habitat.

Now, game cameras — or trail cameras, if you’re less interested in eating what you see — are pretty much reduced to practice. For not that much money you can pick up one of these battery-powered devices, strap it to a tree, and have it automatically snap high-quality pictures of whatever wildlife happens to wander past. But nearly all of the commercially available game cameras have pyroelectric infrared sensors, which trigger on the temperature difference between a warm-blooded animal and the ambient temperature of the background. But what to do when you’re more interested in cold-blooded critters?

Enter [Mirko], who stumbled upon this problem while working with a conservation group in Peru. The group wanted to study snakes, insects, and other ectothermic animals, which are traditionally studied by trapping with pitfalls and other invasive techniques. Unable to rely on PIR, [Mirko] rigged up what amounts to a battery-powered light curtain using a VL53L4CD laser time-of-flight sensor. Mounted above the likely path of an animal, the sensor monitors the height of everything in its field of view. When an animal comes along, cold-blooded or otherwise, RepTrap triggers a remote camera and snaps a picture. Based on the brief video below, it’s pretty sensitive, too.

[Mirko] started out this project using an RP2040 but switched to an ESP32 to take advantage of Bluetooth camera triggering. The need for weatherproofing was also a big driver for the build; [Mirko] is shooting for an IP68 rating, which led to his interesting use of a Hall sensor and external magnet as a power switch.

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Retrotechtacular: How Not To Use Hand Tools

May 6, 2024 by 45 Comments

Whatever you’re doing with your hand tools, by the US Army’s lights, you’re probably doing it wrong. That seems to be the “Green Machine’s” attitude on pliers and screwdrivers, at least, the main stars of this 1943 War Department training film on the horrors of tool abuse.

As kitschy as the film might be, they weren’t wrong. That’s especially true about the dreaded slip-joint pliers, which seem to find their way onto everyone’s list of unloved tools and are shown being used for their true purpose — turning nuts and bolt heads from hexagons into circles. Once that gore is wrapped up, we’re treated to the proper uses of pliers, including the fascinating Bernard-style parallel jaw pliers. We can recall these beauties kicking around the bottom of Dad’s tool kit and being entranced by the mechanism used to keep the jaws parallel and amplify the force applied. Sadly, those pliers are long gone now; Tubalcain did a great review of these pliers a few years back if you need a refresher.

A selection of screwdrivers gets the same treatment, complete with dire warnings against using them as prybars and chisels. Also against the Army Way is using the wrong size screwdriver for the job, lest you strip the head of the screw or break the tool itself. It has to be said that the Plomb Tool Company of Los Angeles, which produced the film, made some fantastic-looking screwdrivers back in the day. The square shanks on some of those straight screwdrivers are enormous, and the wooden handles look so much more comfortable than the greebled-up plastic nonsense manufacturers seem to favor these days. Also interesting is the reference to the new-fangled Phillips screw, not to mention the appearance of a Yankee-style spiral ratcheting screwdriver, another of Dad’s prized acquisitions that thankfully is still around to this day.

What strikes us about these military training films is how many of them were produced. No subject seemed too mundane to get a training film made about it, and so many were made that one is left wondering how there was any time left for soldiering after watching all these films. But really, it’s not much different today, when we routinely pull up a random YouTube video to get a quick visual demo of how to do something we’ve never tried before. The medium may have changed, but visual learning is still a thing.

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The Computers Of Voyager

May 6, 2024 by 62 Comments

After more than four decades in space and having traveled a combined 44 billion kilometers, it’s no secret that the Voyager spacecraft are closing in on the end of their extended interstellar mission. Battered and worn, the twin spacecraft are speeding along through the void, far outside the Sun’s influence now, their radioactive fuel decaying, their signals becoming ever fainter as the time needed to cross the chasm of space gets longer by the day.

But still, they soldier on, humanity’s furthest-flung outposts and testaments to the power of good engineering. And no small measure of good luck, too, given the number of nearly mission-ending events which have accumulated in almost half a century of travel. The number of “glitches” and “anomalies” suffered by both Voyagers seems to be on the uptick, too, contributing to the sense that someday, soon perhaps, we’ll hear no more from them.

That day has thankfully not come yet, in no small part due to the computers that the Voyager spacecraft were, in a way, designed around. Voyager was to be a mission unlike any ever undertaken, a Grand Tour of the outer planets that offered a once-in-a-lifetime chance to push science far out into the solar system. Getting the computers right was absolutely essential to delivering on that promise, a task made all the more challenging by the conditions under which they’d be required to operate, the complexity of the spacecraft they’d be running, and the torrent of data streaming through them. Forty-six years later, it’s safe to say that the designers nailed it, and it’s worth taking a look at how they pulled it off.

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Hackaday Links: May 5, 2024

May 5, 2024 by 16 Comments

It may be hard to believe, but BASIC turned 60 this week. Opinions about the computer language vary, of course, but one thing everyone can agree on is that Professors Kemeny and Kurtz really stretched things with the acronym: “Beginner’s All-Purpose Symbolic Instruction Code” is pretty tortured, after all. BASIC seems to be the one language it’s universally cool to hate, at least in its current incarnations like Visual Basic and VBA. But back in 1964, the idea that you could plunk someone down in front of a terminal, or more likely a teletype, and have them bang out a working “Hello, world!” program with just a few minutes of instruction was pretty revolutionary. Yeah, line numbers and GOTO statements encouraged spaghetti code and engrained bad programming habits, but at least it got people coding. And perhaps most importantly, it served as a “gateway drug” into the culture for a lot of us. Many of us would have chosen other paths in life had it not been for those dopamine hits provided by getting that first BASIC program working. So happy birthday BASIC!

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