Author: Jenny List

3420 Articles

NFC Antennas Have Other Uses

April 22, 2023 by 38 Comments

As NFC chips proliferate, so do the antennas they require for operation, and since many NFC-enabled items are single-use, this means there’s an opportunity to put them to other uses. It’s an avenue pursued by [Brother-live], as he strips the antennas from spent metro tickets and gets experimenting.

The antenna in an NFC-enabled card is a flexible PCB laminated between the plastic outer layers, with the tracks forming a coil round the outside of it. Using some solvent the cards can be easily separated and the antennas retrieved. Once the chip has been removed they can be cleaned up and soldered to, allowing wires to be connected.

What can you do with an NFC antenna? Not a huge amount as you can see in the (Russian language, English subtitles) video below the break, but he tries it as a not-very-good heating pad, a power harvesting antenna from NFC readers, and perhaps most promisingly, as the coil of a moving-coil speaker. We’re not sure how much effort would be worth making on that last front, but we think with a bit of care there might be room for audible improvement.

If you’ve ever been tempted to have a look at an NFC card, it’s a subject we’ve covered before.

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A High Precision ADC That You Can Understand!

April 21, 2023 by 8 Comments

In a world where an analogue to digital converter is all too often an integrated peripheral buried inside a microcontroller, it’s easy to forget how simple these devices can be when built from first principles. An entry in our Op-Amp Challenge from [NNNI] demonstrates this perfectly, it’s a high resolution multi-slope ADC for instrumentation purposes, constructed using a mixture of op-amps, logic chips, and a Raspberry Pi Pico. Best of all, it’s easy to understand, so there’s little of that analogue mystique to worry about.

This type of ADC measures an analogue value by counting how long it takes to charge a capacitor to that voltage. A simple version that measures charge time has a few drawbacks, so this project goes from single slope to multi slope by measuring both charge and discharge times compared to the voltage. Pay attention to component matching and reference stability, and such a design can offer a very high resolution measurement.

The value in this project lies not only in the design itself, but also in the extremely comprehensive description of its operation, which should teach most readers a thing or two. That curvy-line PCB is rather nice, too. We used single slope ADCs to read analogue joysticks back in the day, but we certainly learned something here. Want to see another? This isn’t the first dual slope ADC we’ve seen.

2023 Hackaday.io Op Amp Challenge

Raspberry Pi Camera Conversion Leads To Philosophical Question

April 18, 2023 by 31 Comments

The Raspberry Pi HQ camera module may not quite reach the giddy heights of a DSLR, but it has given experimenters access to a camera system which can equal the output of some surprisingly high-quality manufactured cameras. As an example we have a video from [Malcolm-Jay] showing his Raspberry Pi conversion of a Yashica film camera.

Coming from the viewpoint of a photographer rather than a hardware person, the video is particularly valuable for his discussion of the many lens options beyond a Chinese CCTV lens which can be used with the platform. It uses only the body from the Yashica, but makes a really cool camera that we’d love to own ourselves. If you’re interested in the Pi HQ camera give it a watch below the break, and try to follow some of his lens suggestions.

The broken camera he converted is slightly interesting, and raises an important philosophical question for retro technology geeks. It’s a Yashica Electro 35, a mid-1960s rangefinder camera for 35 mm film whose claim to fame at the time was its electronically controlled shutter timing depending on its built-in light meter. The philosophical question is this: desecration of a characterful classic camera which might have been repaired, or awesome resto-mod? In that sense it’s not just about this project, but a question with application across many other retro tech fields.

A working Electro 35 is a fun toy for an enthusiast wanting to dabble in rangefinder photography, but it’s hardly a valuable artifact and when broken is little more than scrap.  One day we’d love to see a Pi conversion with a built-in focal length converter allowing the use of the original rangefinder mechanism, but we’ll take this one any day!

How about you? Would you have converted this Yashica, repaired it somehow, or just hung onto it because you might get round to fixing it one day? Tell us in the comments!

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A Clock Timebase, No Microcontroller

April 17, 2023 by 20 Comments

Making an electronic clock is pretty easy here in 2023, with a microcontroller capable of delivering as many quartz-disciplined pulses as you’d like available for pennies. But how did engineers generate a timebase back in the old days, and how would you do it today? It’s a question [bicyclesonthemoon] is answering, with a driver for a former railway station clock.

The clock has a mechanism that expects pulses every minute, a +24V pulse on even minutes, and a -24V pulse on odd ones. He received a driver module with it, but for his own reasons wanted a controller without a microcontroller. He also wanted the timebase to be derived from the mains frequency. The result is a delve back into 1970s technology, and the type of project that’s now a pretty rare sight. Using a mixture of 4000 series logic and a few of the ubiquitous 555s [bicyclesonthemoon] recovers 50Hz pulses from the AC, and divides them down to 1 pulse per minute, before splitting into odd and even minutes to drive a pair of relays which in turn drive the clock. We like it, a lot.

Mains-locked clocks are less common than they used to be, but they’re still a thing. Do you still wake up to one?

What Can You Do With Discarded Fish Aggregation Devices

April 13, 2023 by 21 Comments

Often we bring you projects at the end of their trajectory so that you can marvel at a job well done, but sometimes we point you instead to the start of the story. Such is the case with [Brett Smith]’s investigation of discarded fish aggregation buoys, referred to as FADs. These 700-plus dollar devices are deployed in the ocean in the thousands by commercial fishing fleets, and most are not recovered. He’s looking at them from the point of view of re-using their technology in the marine conservation business.

His progress has been documented in a series of short YouTube videos, starting with an introduction that we’ve placed below the break. So far he’s gone on to a complete teardown, and then a detailed look at the PCB. Inside they have a solar charger for a bank of NiCd cells, an echo sounder, a GPS receiver, and an Iridium satellite modem allowing the device to phone home. There’s certainly plenty in there to experiment with, including a few slightly exotic parts, so keep an eye on his channel as we’re sure to see more.

These devices have never made it to Hackaday before, but we have seen an echo sounder on a surfboard.

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Your Fuji Digital Camera Is Hackable

April 8, 2023 by 9 Comments

There was a time when a digital camera was a surprisingly simple affair whose on-board processor didn’t have much in the way of smarts beyond what was needed to grab an image from the sensor and compress it onto some storage. But as they gained more features, over time cameras acquired all the trappings of a fully-fledged computer in their own right, including full-fat operating systems and the accompanying hackability opportunities.

Prominent among camera manufacturers are Fujifilm, whose cameras it turns out have plenty of hacking possibilities. There’s something of a community about them, with all their work appearing in a GitHub repository, and a cracking April Fool in which a Fujifilm camera appears able to be coaxed into running DOOM.

Correction: We’ve since heard from creator [Daniel] who assures us that not only was the DOOM hack very much real, but that he’s released the instructions on how to run the classic shooter on your own Fujfilm X-A2.

Fujifilm cameras past 2017 or so run the ThreadX real-time operating system on a variety of ARM SoCs, with an SQLite data store for camera settings and some custom software controlling the camera hardware. The hackability comes through patching firmware updates, and aside from manipulating the built-in scripting language and accessing the SQLite database, can include code execution.

Don’t have a Fujifilm? They’re not the only hackable camera to be found.

Even Amstrad Spectrums Need Their Bugs Fixing

April 6, 2023 by 2 Comments

The history of the Sinclair ZX Spectrum is one that mirrors the fortunes of the British home computer industry, one of an early 8-bit boom followed by a sharp decline as manufacturers failed to capitalise on the next generation of 16-bit machines. The grey ZX Spectrum on [Keri Szafir]’s bench is one that encapsulates that decline perfectly, being one of the first models produced under the ownership of Amstrad after Sir Clive’s company foundered. Amstrad made many improvements to the Spectrum, but as she demonstrates, there are still some fixes needed.

The machine came her way because of a hum from the tape deck circuitry. The read amplifier was picking up electrical noise, and she fixed it without mods to the circuit but with the simple expedient of powering the analogue circuit from the tape motor switch so it only works when needed.

Beyond that, this machine demonstrates another ’80s innovation, the SCART/Peritel AV connector. These first appeared on early-80s French TV sets, but by the later half of the decade had made it to the UK where Amstrad included support for an adapter cable from the DIN socket on the back of their Spectrum.  Even then they didn’t get it quite right, and she modifies some links on the board to better support it.

Sinclair were famous for on-board bodges, and even in new ownership continued. There’s a reversed transistor and at least one bodged-on component, but of course, it wouldn’t be a Spectrum without bugs, would it!

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