Author: Jenny List

3502 Articles

Free Your Rotary Telephone From Its Wire

September 5, 2026 by 10 Comments

It’s said that a teenager given a rotary telephone in 2026 would be mystified by its operation, yet there are enough surviving instruments for them to be an attractive target for a project. But just what project? [fregacmols] is here with one possibility, turn that old phone into a cellphone.

Connecting to the phone is a subscriber-line interface module, containing all the electronics to simulate a copper phone line. This in turn feeds audio and control wiring to a Lilygo ESP32-S3 board which provides the brains as well as talking to a cellular modem. We especially like that this allows the phone to be used entirely unmodified.

The software does a good job of simulating a North American subscriber line, complete with dial tones, and ringing the phone’s bell on an incoming call. There are a couple of special codes, one to open a wireless network for maintenance, and the other for diagnostic purposes.

Over the years we’ve seen many rotary phone projects, but one which sticks in our mind used an alternative way to connect one to the cellular network.

Hackaday Podcast Ep 385: 3D Printers With Lasers, Wicked RAM Prices, And Reverse Polish Notation

September 4, 2026 by 2 Comments

As the calendar turns a leaf into September, Elliot Williams is joined by Jenny List for our weekly look at all things Hackaday.

In the news, our retrocomputing competition is well under way, but there’s plenty of time to get an entry in if you’ve got a cool old-style project to show us. And then Elliot’s been chasing seismic surveyors in Munich, where they’re looking for geothermal energy.

In the stand-out hacks there’s a discussion of smoothing 3D prints using frickin’ lasers, the effect of unreasonably high RAM and storage prices on the single board computer ecosystem, and an unfortunate air conditioning system that’s tricked into believing it’s a hot day. Finally, we look in depth at PETG, and take a dive into reverse Polish notation.

Download your own personal version of the podcast right here.

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The Birds Outside, Drawn For You Automatically

September 4, 2026 by 24 Comments

With artificial intelligence being the bête noir of the moment, there are some projects using it which maybe don’t bring much to the table. So it’s nice to see one that uses it in a creative way, and delivers something new. [arnegiacomo]’s e-paper screen is a great example, as it draws a picture in real time of whatever birds are outside.

Behind the quite large screen sits a Raspberry Pi 5, and on that is BirdNet-Go, an AI-powered birdsong classifier. A USB microphone catches the birdsong, and Birdnet comes up with the species. The birds on the display are then those species as pictures from 19th century bird spotters guides, assembled into a collage. You can even see what the current set of birds it hears are, live, and they are a representative cross section of the European birds you’d find in Norway where it’s located.

We like this project, both for the bird book vibe it gives, and the creative use of machine classification. Surprisingly this isn’t the first project in this field we have seen over the years.

A Thoroughly Modern Minimalist Transceiver

September 3, 2026 by 8 Comments

Making a radio is so often a case of taking tried and tested designs and working with them to create something new. It’s a safe way to make something that works. [Riyas] however has gone for an entirely different tack, creating an entirely modern transceiver with as much as possible going on in the silicon.

At its heart are three integrated circuits, the familiar Si5351 as a transmit VFO, an Si4372 receiver, and an RP2040 tying it all together. This microcontroller functions both as controller, and as an ADC to provide a software defined radio via its USB port. The Si4372 having an internal SDR architecture and its output being digitized again is not lost on us.

It’s for digital modes and CW only, but we’d venture the opinion that those are where the interesting stuff is anyway. We certainly like it for its simplicity, and also for the one-cable solution it offers. So many other designs need a sound card and extra cables, this one makes for a lot less clutter. We hope we’ll see more development on this design over time, it could become a favorite in the homebrew rig stakes.

Meanwhile the Si5351 is notoriously annoying to program. A while back we covered a library that might help, if you get stuck.

Art of 3D printer in the middle of printing a Hackaday Jolly Wrencher logo

Has FDM 3D Printing Hit Its Peak?

September 2, 2026 by 35 Comments

Over the time Hackaday has been in existence, the art of 3D printing has evolved from a relatively crude hit-and-miss affair to something approaching what we all imagined back then. You can’t yet walk up to a Star Trek replicator and ask for a part, but a modern state of the art consumer or prosumer grade printer will deliver consistent high-resolution parts, and in a surprisingly short time. [The Next Layer] asks whether consumer FDM printers have now reached the point at which they’re about as good as they’re going to get, and whether other technologies hold the future.

It’s a fair point to make that the resolution of a consumer FDM printer may be close to its mechanical limit. Techniques such as input shaping and the adoption of better CoreXY mechanisms mean that prints which once might have relied on SLA can be done in FDM. Healthy competition in the marketplace has delivered high quality colour printing, with tool-changing printers being no longer solely the preserve of the professional. He uses the example of a mobile phone to make the point that new machines have less of a wow factor to deliver, as increments have become less grand.

It’s a persuasive argument, and looking at the printers around us we can see it in action. The difference in ability between a 2020-ish and a 2026 FDM printer are far smaller than those between the same time periods in the last decade. Compare a MakerBot Cupcake and an Ultimaker II, or the Ultimaker and a Prusa Mini, and each is light years ahead of the last. But the best the Mini can do is surprisingly not as far behind as you’d expect to that of their latest, or of the equivalent from Bambu Labs.

Does this means that nothing new is coming in 3D printing? Of course not. UV printing is coming through and will deliver incredible results, as will SLS printing. It’s interesting he devotes little time to SLA printing, perhaps because it’s not as easy a process as FDM. He makes the point that we’ve never had it so good, as the high-end FDM features will appear in modestly priced machines, and we have those other technologies to look forward to.

It’s an interesting discussion, and you can see it below the break.

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How A 1981 RAM Expansion Worked

September 2, 2026 by 56 Comments

Sir Clive Sinclair and his company were notorious for pushing the limits of electronic parts in search of a low price, and his ZX series 8-bit computers were fine examples of this art. The ZX81 came with a meagre 1K of memory, and a popular upgrade was a 16K RAM pack. [Happy Little Diodes] has opened one up, and to his surprise, found many more parts than expected.

Inside the box is a pair of PCBs connected by ribbon cables, one of which has a selection of 74 chips and the other the 4116 RAM chips and a discrete component power circuit. This complexity comes from that cheapness, the 4116 is an inexpensive DRAM chip and requires an eclectic set of power supplies.

The functions of address selection are straightforward enough, as is the DRAM refresh circuitry. The power supply is clever in that it’s a self-oscillating switcher that provides +12 and -5 volts with a single transistor. We particularly like the quench diode in the 12 V Zener diode regulator  circuit.

The ZX81 gave a huge number of British kids their first taste of computing, and learning to use a limited memory space is something that stays with you for life. The film doesn’t mention the most notorious feature of the 16K pack though, that it had been developed with a machine clamped to the desk. Using one in a real-life location was an exercise in not jogging your machine, because the slightest disturbance would trigger a reset.

The ’81 was also famous for its membrane keyboard. Another popular upgrade back then was a new one.

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It’s Teletext, But On The Radio

September 1, 2026 by 18 Comments

Old-school teletext with its pixelated text and block graphics may now be largely a thing of the past, but that doesn’t mean it’s without enthusiasts or there’s no more life in the idea. [M7TJF] has a project which takes teletext and puts it on amateur radio through the magic of AX.25. It’s called CEEFAX Station, in honor of the BBC’s teletext offering from back in the day.

What you get is a Linux package or a Windows executable, which you run and presumably hook the computer up to a radio. It can either be a transmitting node or a receiving one for browsing pages, and there’s an online map to track who’s doing either and on what frequencies. This is all brand new so there’s not much on there at the moment, but we expect that as people try this mode, this will change.

Sadly it’s a little unclear on how the protocol works and how the pages are encoded, but it’s early days. Meanwhile if you hanker for the real thing, it’s still about in some places.