Misc Hacks

4117 Articles

Remembering Heathkit

April 26, 2025 by 22 Comments

While most hams and hackers have at least heard of Heathkit, most people don’t know the strange origin story of the legendary company. [Ham Radio Gizmos] takes us all through the story.

In case you don’t remember, Heathkit produced everything from shortwave radios to color TVs to test equipment and even computers. But, for the most part, when you bought something from them, you didn’t get a finished product. You got a bag full of parts and truly amazing instructions about how to put them together. Why? Well, if you are reading Hackaday, you probably know why. But some people did it to learn more about electronics. Others were attracted by the lower prices you paid for some things if you built them yourself. Others just liked the challenge.

But Heathkit’s original kit wasn’t electronic at all. It was an airplane kit. Not a model airplane, it was an actual airplane. Edward Heath sold airplane kits at the affordable price around $1,000. In 1926, that was quite a bit of money, but apparently still less than a commercial airplane.

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Clickspring’s Experimental Archaeology: Concentric Thin-Walled Tubing

April 25, 2025 by 32 Comments

It’s human nature to look at the technological achievements of the ancients — you know, anything before the 1990s — and marvel at how they were able to achieve precision results in such benighted times. How could anyone create a complicated mechanism without the aid of CNC machining and computer-aided design tools? Clearly, it was aliens.

Or, as [Chris] from Click Spring demonstrates by creating precision nesting thin-wall tubing, it was human beings running the same wetware as what’s running between our ears but with a lot more patience and ingenuity. It’s part of his series of experiments into how the craftsmen of antiquity made complicated devices like the Antikythera mechanism with simple tools. He starts by cleaning up roughly wrought brass rods on his hand-powered lathe, followed by drilling and reaming to create three tubes with incremental precision bores. He then creates matching pistons for each tube, with an almost gas-tight enough fit right off the lathe.

Getting the piston fit to true gas-tight precision came next, by lapping with a jeweler’s rouge made from iron swarf recovered from the bench. Allowed to rust and ground to a paste using a mortar and pestle, the red iron oxide mixed with olive oil made a dandy fine abrasive, perfect for polishing the metal to a high gloss finish. Making the set of tubes concentric required truing up the bores on the lathe, starting with the inner-most tube and adding the next-largest tube once the outer diameter was lapped to spec.

Easy? Not by a long shot! It looks like a tedious job that we suspect was given to the apprentice while the master worked on more interesting chores. But clearly, it was possible to achieve precision challenging today’s most exacting needs with nothing but the simplest tools and plenty of skill. Continue reading “Clickspring’s Experimental Archaeology: Concentric Thin-Walled Tubing” →

An Absolute Zero Of A Project

April 16, 2025 by 12 Comments

How would you go about determining absolute zero? Intuitively, it seems like you’d need some complicated physics setup with lasers and maybe some liquid helium. But as it turns out, all you need is some simple lab glassware and a heat gun. And a laser, of course.

To be clear, the method that [Markus Bindhammer] describes in the video below is only an estimation of absolute zero via Charles’s Law, which describes how gases expand when heated. To gather the needed data, [Marb] used a 50-ml glass syringe mounted horizontally on a stand and fitted with a thermocouple. Across from the plunger of the syringe he placed a VL6180 laser time-of-flight sensor, to measure the displacement of the plunger as the air within it expands.

Data from the TOF sensor and the thermocouple were recorded by a microcontroller as the air inside the syringe was gently heated. Plotting the volume of the gas versus the temperature results shows a nicely linear relationship, and the linear regression can be used to calculate the temperature at which the volume of the gas would be zero. The result: -268.82°C, or only about four degrees off from the accepted value of -273.15°. Not too shabby.

[Marb] has been on a tear lately with science projects like these; check out his open-source blood glucose measurement method or his all-in-one electrochemistry lab.

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Inside An Edison Phonograph

April 5, 2025 by 14 Comments

If you think of records as platters, you are of a certain age. If you don’t remember records at all, you are even younger. But there was a time when audio records were not flat — they were drums, which was how the original Edison phonograph worked. [Our Own Devices] did a video earlier showing one of these devices, but since it was in a museum, he didn’t get to open it up. Lucky for us, he now has one of his own, and we get to see inside in the video below.

Ironically, Edison was deaf yet still invented the phonograph. While he did create the working phonograph — his self-identified most important invention — the original invention wasn’t commercially viable. You could record and playback audio on tin foil wrapped around a drum. But you couldn’t remove the foil without destroying it.

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Shrinking Blinky As Far As Possible

April 1, 2025 by 39 Comments

Many of us know the basic Blink Arduino sketch, or have coded similar routines on other microcontrollers. Flashing an LED on and off—it doesn’t get much simpler than that. But how big should a blink sketch be? Or more importantly, how small could you get it? [Artful Bytes] decided to find out.

The specific challenge? “Write a program that runs on a microcontroller and blinks an LED. The ON and OFF times should be as close to 1000 ms as possible.” The challenge was undertaken using a NUCLEO-L432KC Cortex-M4 with 256 K of flash and 64 K of RAM.

We won’t spoil the full challenge, but it starts out with an incredibly inefficient AI & cloud solution. [Artful Bytes] then simplifies by switching to an RTOS approach, before slimming down further with C, assembly, and then machine code. The challenge was to shrink the microcontroller code as much as possible. However, you might notice the title of the video is “I Shrunk Blinky to 0 Bytes.” As it turns out, if you eliminate the digital code-running hardware entirely… you can still blink an LED with analog hardware. So, yes. 0 bytes is possible.

We’ve featured the world’s smallest blinky before, too, but in a physical sense rather than with regards to code size.

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A Music Box Commanded By NFC Tags

March 31, 2025 by 7 Comments

[Luca Dentella] recently encountered a toy, which was programmed to read different stories aloud based on the figurine placed on top. It inspired him to build an audio device using the same concept, only with music instead of children’s stories.

The NFC Music Player very much does what it says on the tin. Present it with an NFC card, and it will play the relevant music in turn. An ESP32 WROOM-32E lives at the heart of the build, which is hooked up over I2S with a MAX98357A Class D amplifier for audio output. There’s also an SD card slot for storing all the necessary MP3s, and a PN532 NFC reader for reading the flash cards that activate the various songs. Everything is laced up inside a simple 3D-printed enclosure with a 3-watt full range speaker pumping out the tunes.

It’s an easy build, and a fun one at that—there’s something satisfying about tossing a flash card at a box to trigger a song. Files are on Github for the curious. We’ve featured similar projects before, like the Yaydio—a fun NFC music player for kids. Video after the break.

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3D-Printed Scanner Automates Deck Management For Trading Card Gamers

March 26, 2025 by 11 Comments

Those who indulge in trading card games know that building the best deck is the key to victory. What exactly that entails is a mystery to us muggles, but keeping track of your cards is a vital part of the process, one that this DIY card scanner (original German; English translation) seeks to automate.

At its heart, [Fraens]’ card scanner is all about paper handling, which is always an engineering task fraught with peril. Cards like those for Magic: The Gathering and other TCGs are meant to be handled by human hands, and automating the task of flipping through them presents some challenges. [Fraens] uses a pair of motorized 3D-printed rollers with O-rings to form a conveyor belt that can pull one card at a time off the bottom of a deck. An adjustable retaining roller made from the most adorable linear bearing we’ve ever seen ensures that only one card at a time is pulled from the hopper onto an imaging platen. An adjustable mount holds a smartphone to take a picture of the card, which is fed into an app that extracts all the details and categorizes the cards in the deck.

Aside from the card handling mechanism, there are some pretty slick details to this build. The first is that [Fraens] noticed that the glossy finish on some cards interfered with scanning, leading him to add a diffused LED ringlight to the rig. If an image isn’t scannable, the light goes through a process of dimming and switching colors until a good scan is achieved. Also, to avoid the need to modify the existing TCG deck management app, [Fraens] added a microphone to the control side of the scanner that listens for the sounds the app makes when it scans cards. And if Magic isn’t your thing, the basic mechanism could easily be modified to scan everything from business cards to old family photos.

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