A Retro Touch Pad You Can Use On Modern Computers

As [Jan Derogee] explains in the faux-retro video after the break, drawing on classic 8-bit computers was something of a pain. The rudimentary light pens and joysticks of the 1980s allowed for free-form input, but were clumsy and awkward to use. Which is why he set out to create an ideal drawing device for the C64 using modern electronics. For the sake of completion, he also gave it a USB HID mode so it would work on somewhat more modern computers.

His device, which he’s calling the Commo Pad, looks like it could have been transported here directly from the 1980s, but it’s built from entirely new hardware. The case is actually made of wood that [Jan] sanded and painted to give it that chunky plastic aesthetic that we all know and love, and the retro artwork on the touch panel really goes a long way to sell the vintage vibe.

Speaking of which, the touch panel is perhaps the most interesting component of the entire build. It’s actually a resistive panel that was meant for mounting to an LCD that [Jan] has connected to an Arduino. All he had to do was provide a stable frame for it and print out some art work to slide in behind it.

The Arduino and associated electronics allow the Commo Pad to be picked up by the C64 as either a joystick or mouse, which means it doesn’t need any custom software on the computer side to function. Similarly, it can also mimic a USB mouse if you want to plug it into something made a bit later than 1982. Should you be so inclined to make it wireless, the addition of a Bluetooth seems like it would be relatively trivial.

If the Commo Pad doesn’t have enough of a retro-futuristic vibe for your tastes, we recently covered a custom optical touch panel that looked like it could double as a prop from Blade Runner which might do the trick.

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Random Numbers From Outer Space

Need a random number? Sure, you could just roll a die, but if you do, you might invite laughter from nearby quantum enthusiasts. If it’s truly, unpredictably random numbers you need, look no farther than the background radiation constantly bombarding us from the safety of its celestial hideout.

In a rare but much appreciated break from the Nixie tube norm of clock making, [Alpha-Phoenix] has designed a muon-powered random number generator around that warm, vintage glow. Muons are subatomic particles that are like electrons, but much heavier, and are created when pions enter the atmosphere and undergo radioactive decay. The Geiger-Müller tube, mainstay of Geiger counters the world over, detects these incoming muons and uses them to generate the number.

Inside the box, a 555 in astable mode drives a decade counter, which outputs the numbers 0-9 sequentially on the Nixie via beefy transistors. While the G-M tube waits for muons, the numbers just cycle through repeatedly, looking pretty. When a muon hits the tube, a second 555 tells the decade counter to stop immediately. Bingo, you have your random number! The only trouble we can see with this method is that if you need a number right away, you might have to go get a banana and wave it near the G-M tube.

Whether this all makes sense or not, you should check out [Alpha-Phoenix]’s project video, which is as entertaining as it is informative. He’s planning a follow-up video focused on the randomness of the G-M tube, so look out for that.

Looking for a cheaper way to catch your random numbers? You can do it with a fish tank, some air pumps, and a sprinkle of OpenCV.

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Get Compressed Air From Falling Water With The Trompe

If you’re like us, understanding the processes and methods of the early Industrial Revolution involved some hand waving. Take the blast furnace, which relies on a steady supply of compressed air to stoke the fire and supply the oxygen needed to smelt iron from ore. How exactly was air compressed before electricity? We assumed it would have been from a set of bellows powered by a water wheel, and of course that method was used, but it turns out there’s another way to get compressed air from water: the trompe.

As [Grady] from Practical Engineering explains in the short video below, the trompe was a clever device used to create a steady supply of high-pressure compressed air. To demonstrate the process, he breaks out his seemingly inexhaustible supply of clear acrylic piping to build a small trompe. The idea is to use water falling around a series of tubes to create a partial vacuum and entrain air bubbles. The bubbles are pulled down a vertical tube by the turbulence of the water, and then enter a horizontal section where the flow evens out. The bubbles rise to the top of the horizontal tube where they are tapped off by another vertical tube, as the degassed water continues into a second vertical section, the height of which determines the pressure of the stored air. It’s ingenious, requiring no power and no moving parts, and scales up well – [Grady] relates a story about one trompe that provided compressed air commercially for mines in Canada.

Need an electricity-free way to pump water instead of air? Check out this hydraulic ram pump that takes its power from the water it pumps.

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These Bit Twiddling Tricks Will Make Your Coworkers Hate You

In the embedded world, twiddling a few bits is expected behavior. Firmware is far enough down the stack that the author may care about the number of bits and bytes used, or needs to work with registers directly to make the machine dance. Usually these operations are confined to the typical shifting and masking but sometimes a problem calls for more exotic solutions. If you need to descend down these dark depths you invariably come across the classic Bit Twiddling Hacks collected by [Sean Eron Anderson]. Here be dragons.

Discussions of bit math are great opportunities to revisit Wikipedia’s superb illustrations

Bit Twiddling Hacks is exactly as described; a page full of snippets and suggestions for how to perform all manner of bit math in convenient or efficient ways. To our surprise upon reading the disclaimer at the top of the page, [Sean] observes that so many people have used the contents of the page that it’s effectively all been thoroughly tested. Considering how esoteric some of the snippets are we’d love to know how the darkest corners found use.

The page contains a variety of nifty tricks. Interview content like counting set bits makes an early appearance.  There’s more esoteric content like this trick for interleaving the bits in two u16’s into a single u32, or rounding up to the next power of two by casting floats. This author has only been forced to turn to Bit Twiddling Hacks on one occasion: to sign extend the output from an unfortunately designed sensor with unusual length registers.

Next time you need to perform an operation with bitmatch, check out Bit Twiddling Hacks. Have you ever needed it in production? How did you use it? We’d love to hear about it in the comments.

The Flexible Permanence Of Copper Tape Circuits

Somewhere between shoving components into a breadboard temporarily and committing them to a piece of protoboard or a PCB lies the copper tape method. This flexible Manhattan-style method of circuitry formed the basis for [Bunnie Huang]’s Chibitronics startup, and has since inspired many to stop etching boards and start fetching hoards of copper tape.

[Hales] hit the ground running when he learned about this method, and has made many a copper tape circuit in the last year or so. He offers several nice tips on his site that speak from experience with this method, and he’ll even show you how to easily work an SMD breakout board into the mix.

Generally speaking, [Hales] prefers plywood as the substrate to paper or cardboard for durability. He starts by drawing out the circuit and planning where all the tape traces will go and how wide they need to be. Then he lays out copper traces and pads, rubs the tape against the substrate to make it adhere strongly, and reinforces joints and laps with solder before adding the components. As you can see, copper tape circuits can get pretty complicated if you use Kapton tape as insulation between stacked layers of traces.

Copper and Kapton (polyimide) tape are just two of the many useful tapes you may not be aware of. Stick with us a moment and check out [Nava Whiteford]’s exploration of various adhesive marvels.

Camcorder Viewfinder Converted To Diminutive Vector Display

We generally cast a skeptical eye at projects that claim some kind of superlative. If you go on about the “World’s Smallest” widget, the chances are pretty good that someone will point to a yet smaller version of the same thing. But in the case of what’s touted as “The world’s smallest vector monitor”, we’re willing to take that chance.

If you’ve seen any of [Arcade Jason]’s projects before, you’ll no doubt have noticed his abiding affection for vector displays. We’re OK with that; after all, many of the best machines from the Golden Age of arcade games such as Asteroids and Tempest were based on vector graphics. None so small as the current work, though, based as it is on the CRT from an old camcorder’s viewfinder. The tube appears to be about 3/4″ (19 mm) in diameter, and while it still had some of its original circuitry, the deflection coils had to be removed. In their place, [Jason] used a ferrite toroid with two windings, one for vertical and one for horizontal. Those were driven directly by a two-channel push-pull audio amplifier to make patterns on the screen. Skip to 15:30 in the video below to see the display playing [Jerobeam Fenderson]’s “Oscilloscope Music”.

As much as we’d love to see a tiny game of Battlezone played on the diminutive display, there’s only so much it can do. Maybe an analog version of this adorable digital oscilloscope would be possible?

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A Luggable Computer For The Raspberry Pi Era

Today, computers are separated into basically two categories: desktops and laptops. But back in the early 1980s, when this ideological line in the sand was still a bit blurry, consumer’s had a third choice. Known as “portable computers” at the time, and often lovingly referred to as luggables by modern collectors, these machines were technically small enough to take with you on a plane or in the car.

Improvements in miniaturization ultimately made the portable computer obsolete, but that doesn’t mean some people still don’t want one. [Dave Estes] has been working on his own modern take on idea that he calls Reviiser, and so far it looks like it checks off all the boxes. With the addition of a rather hefty battery pack, it even manages to be more practical than the vintage beasts that inspired it.

In the video after the break, [Dave] walks us through some of the highlights of his luggable build, such as the fold-down mechanical keyboard, gloriously clunky mechanical power switches, and the integrated touch screen. We also really like the side-mounted touch pad, which actually looks perfectly usable given the largely keyboard driven software environment [Dave] has going on the internal Raspberry Pi 4. With a removable 30,000 mAh battery pack slotted into the back of the machine, he’ll have plenty of juice for his faux-retro adventures.

[Dave] mentions that eventually he’s looking to add support for “cartridges” which will allow the user to easily slot in new hardware that connects to the Pi’s GPIO pins. This would allow for a lot of interesting expansion possibilities, and fits in perfectly with the Reviiser’s vintage aesthetic. It would also go a long way towards justifying the considerable bulk of the machine; perhaps even ushering in a revival of sorts for the luggable computer thanks to hardware hackers who want a mobile workstation with all the bells and whistles.

Right now there isn’t a lot of detail on how you can build your own Reviiser, but [Dave] says more info will be added to his site soon. In the meantime, you can check out some of the similar projects we’ve seen recently to get some inspiration for your own Luggable Pi.

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