Author: Jenny List

3307 Articles

Cheap VHF Antenna? Can Do!

November 18, 2025 by 6 Comments

The magnetic loop antenna is a familiar sight in radio amateur circles as a means to pack a high performance HF antenna into a small space. It takes the form of a large single-turn coil made into a tuned circuit with a variable capacitor, and it provides the benefits of good directionality and narrow bandwidth at the cost of some scary RF voltages and the need for constant retuning. As [VK3YE] shows us though, magnetic loops are not limited to HF — he’s made a compact VHF magnetic loop using a tin can.

It’s a pretty simple design; a section from the can it cut out and made into a C shape, with a small variable capacitor at the gap. The feed comes in at the bottom, with the feed point about 20 % of the way round the loop for matching. The bandwidth is about 100 MHz starting from the bottom of the FM broadcast band, and he shows us it receiving broadcast, Airband, and 2 meter signals. It can be used for transmitting too and we see it on 2 meter WSPR, but we would have to wonder whether the voltages induced by higher power levels might be a little much for that small capacitor.

He’s at pains to point out that there are many better VHF antennas as this one has no gain to speak of, but we can see a place for it. It’s tiny, if you’re prepared to fiddle with the tuning its high Q gets rid of interference, and its strong side null means it can also reduce unwanted signals on the same frequency. We rather like it, and we hope you will too after watching the video below.

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2025 Component Abuse Challenge: The VIA Makes Noise, Again

November 14, 2025 by 3 Comments

In the days of 8-bit home computing, the more fancy machines had sound chips containing complete synthesizers, while budget machines made do with simple output ports connected to a speaker — if they had anything at all. [Normal User] appears to be chasing the later route, making PCM sound by abusing the serial port on a 6522 VIA chip.

A serial port is when you think about it, a special case of a one-bit output port. It’s designed for byte data communication but it can also carry a PCM data stream. We’ve seen this used with microcontrollers and peripherals such as the I2S port plenty of times here at Hackaday, to produce such things as NTSC video. The 1970s-spec equivalent might not be as fast as its modern equivalent, but it’s capable of delivering audio at some level. The machine in question is a Ben Eater breadboard 6502 with a World’s Worst Video Card, and as you can hear in the video below the break, it’s not doing a bad job for the era,

If you think this hack sounds a little familiar then in a sense you’re right, because Ben Eater himself made noises with a 6522. However it differs from that in that he used the on-board timers instead. After all, the “V” in “VIA” stands for “versatile”.

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Hackaday Podcast Episode 345: A Stunning Lightsaber, Two Extreme Cameras, And Wrangling Roombas

November 14, 2025 by 1 Comment

It’s a wet November evening across Western Europe, the steel-grey clouds have obscured a rare low-latitude aurora this week, and Elliot Williams is joined by Jenny List for this week’s podcast. And we’ve got a fine selection for your listening pleasure!

The 2025 Component Abuse Challenge has come to an end, so this week you’ll be hearing about a few of the entries. We’ve received an impressive number, and as always we’re bowled over by the ingenuity of Hackaday readers in pushing parts beyond their limits.

In the news is the potential discovery of a lost UNIX version in a dusty store room at the University of Utah, Version 4 of the OS, which appeared in 1973. Check out your own stores, for hidden nuggets of gold. In the hacks, we have two cameras at the opposite end of the resolution spectrum, but sharing some impressive reverse engineering. Mouse cameras and scanner cameras were both a thing a couple of decades ago, and it’s great to see people still pushing the boundaries. Then we look at the challenge of encoding Chinese text as Morse code, an online-upgraded multimeter, the art of making lenses for an LED lighting effect, and what must be the best recreation of a Star Wars light sabre we have ever seen. In quick hacks we have a bevvy of Component Abuse Challenge projects, a Minecraft server on a smart light bulb, and a long term test of smartphone battery charging techniques.

We round off with a couple of our long-form pieces, first the uncertainties about iRobot’s future and what it might mean for their ecosystem — think: cheap hackable robotics platform! — and then a look at FreeBSD as an alternative upgrade path for Windows users. It’s a path not without challenges, but the venerable OS still has plenty to give.

As always, you can listen using the links below, and we’ve laidout links to all the articles under discussion at the bottom of the page.

Download our finest MP3 right here.

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The Pi 500 Turned Overkill Bluetooth Keyboard

November 13, 2025 by 12 Comments

Perhaps we’ve all found ourselves at one time or another with more computers in use than keyboards and other peripherals at hand to use them with. With a single user you can make do with remote terminals or by simply plugging and unplugging, but with multiple users it’s not so easy.

CNX Software’s [Jean-Luc Aufranc] had just such a problem involving broken keyboards and a forgotten wireless dongle, but fortunately he had just reviewed the latest version of the Raspberry Pi 500 all-in-one computer with the fancy mechanical switches. His keyboard solution is inspired but completely overkill: to use the full power of the compact Linux machine to emulate a Bluetooth keyboard.

At the heart of this hack is btferret, a Bluetooth library. Run the appropriate software on your Pi, and straight away you’ll have a Bluetooth keyboard. It seems there’s a bit of keymap tomfoolery to be had, and hitting the escape key terminates the program — we would be caught by that SO many times! — but it’s one of those simple hacks it pays to know about in case like him you need to get out of a hole and happen to have one of the range of Pi all-in-one machines to hand.

2025 Component Abuse Challenge: Light An LED With Nothing

November 12, 2025 by 11 Comments

Should you spend some time around the less scientifically informed parts of the internet, it’s easy to find “Free power” stories. Usually they’re some form of perpetual motion machine flying in the face of the laws of conservation of energy, but that’s not to say that there is no free power.

The power just has to come from somewhere, and if you’re not paying for it there’s the bonus. [joekutz] has just such a project, lighting up LEDs with no power source or other active electronics.

Of course, he’s not discovered perpetual motion. Rather, while an LED normally requires a bit of current to light up properly, it seems many will produce a tiny amount of light on almost nothing. Ambient electromagnetic fields are enough, and it’s this effect that’s under investigation. Using a phone camera and a magnifier as a light detector he’s able to observe the feeble glow as the device is exposed to ambient fields.

In effect this is using the LED as the very simplest form of radio receiver, a crystal set with no headphone and only the leads, some wires, and high value resistors as an antenna. The LED is after all a diode, and it can thus perform as a rectifier. We like the demonstration even if we can’t quite see an application for it.

While we’re no longer taking new entries for the 2025 Component Abuse Challenge, we’ve still got plenty of creative hacks from the competition to show off. We’re currently tabulating the votes, and will announce the winners of this particularly lively challenge soon.

2025 Hackaday Component Abuse Challenge

2025 Component Abuse Challenge: The Slip Ring In Your Parts Bin

November 11, 2025 by 33 Comments

If you’re familiar with electrical slip rings as found in motors and the like you’ll know them as robust assemblies using carefully chosen alloys and sintered brushes, able to take the load at high RPM for a long time. But not all slip ring applications need this performance. For something requiring a lot less rotational ability, [Luke J. Barker] has something from his parts bin, and probably yours too. It’s an audio jack.

On the face of it, a 1/4″ jack might seem unsuitable for this task, being largely a small-signal audio connector. But when you consider its origins in the world of telephones it becomes apparent that perhaps it could do so much more. It works for him, but we’d suggest if you’d like to follow his example, to use decent quality plugs and sockets.

This is an entry in our 2025 Component Abuse Challenge, and we like it for thinking in terms of the physical rather than the electrical. The entry period for this contest will have just closed by the time you read this, so keep an eye out for the official results soon.

2025 Hackaday Component Abuse Challenge

Another Thermal Printer, Conquered

November 11, 2025 by 13 Comments

The arrival of cheap thermal printer mechanisms over the last few years has led to a burst of printer hacking in our community, and we’re sure many of you will like us have one knocking around somewhere. There are a variety of different models on the market, and since they often appear in discount stores we frequently see new ones requiring their own reverse engineering effort. [Mel] has done some work on just such a model, the Core Innovation CTP-500, which can be found at Walmart.

The write-up is a tale of Bluetooth reverse engineering as much as it is one about the device itself, as he sniffs the protocol it uses, and finds inspiration from the work of others on similar peripherals. The resulting Python app can be found in his GitHub repository, and includes a TK GUI for ease of use. We like this work and since there’s an analogous printer from a European store sitting on the Hackaday bench as we write this, it’s likely we’ll be giving it a very close look.

Meanwhile if [Mel] sounds a little familiar it might be because of their print-in-place PCB holder we featured recently.