Author: Al Williams

4315 Articles

A Paper Caper: The Hole Data

November 20, 2025 by 26 Comments

Since the dawn of computers, we’ve tried different ways to store data. These days, you grab data over the network, but you probably remember using optical disks, floppies, or, more recently, flash drives to load something into your computer. Old computers had to use a variety of methods, such as magnetic tape. But many early computers used some technology that existed from the pre-computer era, like punched cards or, as [Anthony Francis-Jones] shows us, paper tape.

Paper tape was common in TeleType machines and some industrial applications. In fact, as early as 1725, looms could use paper tape, which would eventually lead to punched cards. For computers, there were two common variations that differed in how many holes were punched across the tape: 5 or 8. There was also a small sprocket hole that allowed a gear to move the tape forward through a reader.

Continue reading “A Paper Caper: The Hole Data” →

Gilbert Cell Lacks Sullivan

November 20, 2025 by 7 Comments

If you’ve ever used an NE602 or similar IC to build a radio, you might have noticed that the datasheet has a “gilbert cell” mixer. What is that? [Electronics for the Inquisitive Experimenter] explains them in a recent video. The gilbert cell is a multiplier, and multiplying two waveforms will work to mix them together.

At the heart of the gilbert cell is essentially three differential amplifiers that share a common current source. The video shows LTSpice simulations of the circuits as he explains them.

Continue reading “Gilbert Cell Lacks Sullivan” →

Rare Filament Makes Weird Benchies

November 20, 2025 by 21 Comments

[Zack], in addition to being a snappy dresser, has a thing for strange 3D printing filament. How strange? Well, in a recent video, he looks at filaments that require 445 C. Even the build plate has to be super hot. He also looks at filament that seems like iron, one that makes you think it is rubber, and a bunch of others.

As you might expect, he’s not using a conventional 3D printer. Although you might be able to get your more conventional printer to handle some of these, especially with some hacking. There is filament with carbon fiber, glass fiber, and more exotic add-ons.

Most of the filaments need special code to get everything working. While you might think you can’t print these engineering filaments, it stands to reason that hobby-grade printers are going to get better over time (as they already have). If the day is coming when folks will be able to print any of these on their out-of-the-box printer, we might as well start researching them now.

If you fancy a drinking game, have a shot every time he changes shots and a double when the Hackaday Prize T-shirt shows up.

Continue reading “Rare Filament Makes Weird Benchies” →

Pong Gets The Boot

November 20, 2025 by 5 Comments

You might be surprised to find out that [Akshat Joshi’s] Pong game that fits in a 512-byte boot sector isn’t the first of its kind. But that doesn’t mean it isn’t an accomplishment to shoehorn useful code in that little bitty space.

As you might expect, a game like this uses assembly language. It also can’t use any libraries or operating system functions because there aren’t any at that particular time of the computer startup sequence. Once you remember that the bootloader has to end with two magic bytes (0x55 0xAA), you know you have to get it all done in 510 bytes or less.

This version of Pong uses 80×25 text mode and writes straight into video memory. You can find the code in a single file on GitHub. In the old days, getting something like this working was painful because you had little choice but reboot your computer to test it and hope it went well. Now you can run it in a virtual machine like QEMU and even use that to debug problems in ways that would have made a developer from the 1990s offer up their life savings.

We’ve seen this before, but we still appreciate the challenge. We wonder if you could write Pong in BootBasic?

Hackers Can’t Spend A Penny

November 19, 2025 by 91 Comments

We aren’t here to praise the penny, but rather, to bury it. The penny, and its counterparts, have been vanishing all around the world as the cost of minting one far outweighs its value. But hackers had already lost a big asset: real copper pennies, and now even the cheaply made ones are doomed to extinction.

If you check your pockets and find a pre-1982 penny, it’s almost all copper. Well, 95% of its slightly-more-than-3-gram heft is pure copper. Since then, the copper penny’s been a fraud, weighing 2.5 g and containing only a 2.5% copper plate over a zinc core. During WWII, they did make some oddball steel pennies, but that was just a temporary measure.

Continue reading “Hackers Can’t Spend A Penny” →

Tech In Plain Sight: Pneumatic Tubes

November 17, 2025 by 44 Comments

Today, if you can find a pneumatic tube system at all, it is likely at a bank drive-through. A conversation in the Hackaday bunker revealed something a bit surprising. Apparently, in some parts of the United States, these have totally disappeared. In other areas, they are not as prevalent as they once were, but are still hanging in there. If you haven’t seen one, the idea is simple: you put things like money or documents into a capsule, put the capsule in a tube, and push a button. Compressed air shoots the capsule to the other end of the tube, where someone can reverse the process to send you something back.

These used to be a common sight in large offices and department stores that needed to send original documents around, and you still see them in some other odd places, like hospitals or pharmacy drive-throughs, where they may move drugs or lab samples, as well as documents. In Munich, for example, a hospital has a system with 200 stations and 1,300 capsules,  also known as carriers. Another medical center in Rotterdam moves 400 carriers an hour through a 16-kilometer network of tubes. However, most systems are much smaller, but they still work on the same principle.

Continue reading “Tech In Plain Sight: Pneumatic Tubes” →

The King Of Rocket Photography

November 16, 2025 by 27 Comments

If you are a nerdy kid today, you have your choice of wondrous gadgets and time wasters. When we were nerdy kids, our options were somewhat limited: there was ham radio, or you could blow things up with a chemistry set. There were also model rockets. Not only were model rockets undeniably cool, but thanks to a company called Estes, you could find ready-to-go kits and gear that made it possible to launch something into the heavens, relatively speaking. But what about photographic proof? No live streams or digital cameras. But there was the Estes AstroCam 100. [Bill Engar] remembers the joy of getting film from your rocket developed.

Of course, photography was another nerdy kid staple, so maybe you did your own darkroom work. Either way, the Astrocam 110 was a big improvement over the company’s earlier Camroc. In 1965, if you wanted to fly Camroc, you had to cut a 1.5-inch piece of film in a darkroom and mount it just to get one terrible black-and-white photo. Or, you could buy the film canisters loaded if you had the extra money, which, of course, you didn’t.

Continue reading “The King Of Rocket Photography” →