Powering On A 1985 Photophone CP220 Videoconference System

January 6, 2026 by 9 Comments

The concept of remote video calls has been worked on since Bell’s phone company began pitching upgrading from telegrams to real-time voice calls. It wasn’t until the era of digital video and real-time video compression that commercial solutions became feasible, with the 1985 Image Data Corporation Photophone CP220 being an early example. The CP220 is also exceedingly rare due to costing around $25,000 USD when adjusted to inflation. This makes the teardown and repair on the [SpaceTime Junction] channel a rather unique experience.

Perhaps the coolest part of the device is that the manual is integrated into the firmware, allowing you to browse through it on the monochrome CRT. Unfortunately after working fine for a while the device released the magic smoke, courtesy of the usual Rifa capacitors doing their thing. This is why a full teardown was necessary, resulting in the PSU being dug out and having said capacitors swapped.

After this deal the device powered on again, happily accepting a video input and saving screenshots to the floppy drive before it was replaced with a FDD emulator running FlashFloppy firmware. Unfortunately no video call was attempted, probably because of the missing camera and having to set up a suitable POTS landline for the built-in modem. Hopefully we’ll see that in an upcoming video to see what we common folk were missing out on back in the day.

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Active Ideal Full Bridge Rectifier Using TEA2208T

December 27, 2025 by 31 Comments

Everyone loves a full-wave bridge rectifier, but there’s no denying that they aren’t 100% efficient due to the diode voltage drop. Which isn’t to say that with some effort we cannot create an ideal bridge rectifier using active components, as demonstrated by [Mousa] with an active bridge circuit. This uses the NXP TEA2208T active bridge rectifier controller, along with the requisite four MOSFETs.

Comparing a diode bridge rectifier with an active bridge rectifier. (Credit: Mousa, YouTube)
Comparing a diode bridge rectifier with an active bridge rectifier. (Credit: Mousa, YouTube)

Taking the circuit from the datasheet, a PCB was created featuring four FDD8N50NZ MOSFETs in addition to the controller IC. These were then compared to a diode-based bridge rectifier, showing the imperfections with the latter when analyzing the output using an oscilloscope.

As expected, the active rectifier’s output was also one volt higher than the diode bridge rectifier, which is another small boost to overall efficiency. According to NXP’s product page, there’s about a 1.4% efficiency gain at 90 VAC, with the chip being promoted for high-efficiency operations. When you consider that many designs like computer PSUs feature one or more diode bridge rectifiers often strapped to heatsinks, the appeal becomes apparent. As for [Mousa], he put this particular board in his laboratory PSU instead of the diode bridge rectifier, because why not.

Perhaps the biggest impediment to using an active rectifier is the cost, with the TEA2208T coming in at $4 on DigiKey for a quantity of 100, in addition to the MOSFETs, PCB, etc. If power efficiency isn’t the goal, then some wasted power and an aluminium heatsink is definitely cheaper.

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One of the photo-detector spheres of ARCA (Credit: KM3NeT)

Confirmation Of Record 220 PeV Cosmic Neutrino Hit On Earth

August 26, 2025 by 11 Comments

Neutrinos are exceedingly common in the Universe, with billions of them zipping around us throughout the day from a variety of sources. Due to their extremely low mass and no electric charge they barely ever interact with other particles, making these so-called ‘ghost particles’ very hard to detect. That said, when they do interact the result is rather spectacular as they impart significant kinetic energy. The resulting flash of energy is used by neutrino detectors, with most neutrinos generally pegging out at around 10 petaelectronvolt (PeV), except for a 2023 event.

This neutrino event which occurred on February 13th back in 2023 was detected by the KM3NeT/ARCA detector and has now been classified as an ultra-high energy neutrino event at 220 PeV, suggesting that it was likely a cosmogenic neutrinos. When we originally reported on this KM3-230213A event, the data was still being analyzed based on a detected muon from the neutrino interaction even, with the researchers also having to exclude the possibility of it being a sensor glitch.

By comparing the KM3-230213A event data with data from other events at other detectors, it was possible to deduce that the most likely explanation was one of these ultra-high energy neutrinos. Since these are relatively rare compared to neutrinos that originate within or near Earth’s solar system, it’ll likely take a while for more of these detection events. As the KM3NeT/ARCA detector grid is still being expanded, we may see many more of them in Earth’s oceans. After all, if a neutrino hits a particle but there’s no sensor around to detect it, we’d never know it happened.

Top image: One of the photo-detector spheres of ARCA (Credit: KM3NeT)

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Hackaday Links: June 22, 2025

June 22, 2025 by 16 Comments

Hold onto your hats, everyone — there’s stunning news afoot. It’s hard to believe, but it looks like over-reliance on chatbots to do your homework can turn your brain into pudding. At least that seems to be the conclusion of a preprint paper out of the MIT Media Lab, which looked at 54 adults between the ages of 18 and 39, who were tasked with writing a series of essays. They divided participants into three groups — one that used ChatGPT to help write the essays, one that was limited to using only Google search, and one that had to do everything the old-fashioned way. They recorded the brain activity of writers using EEG, in order to get an idea of brain engagement with the task. The brain-only group had the greatest engagement, which stayed consistently high throughout the series, while the ChatGPT group had the least. More alarmingly, the engagement for the chatbot group went down even further with each essay written. The ChatGPT group produced essays that were very similar between writers and were judged “soulless” by two English teachers. Go figure.

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Hackaday Podcast Ep 322: Fake Hackaday Writers, New Retro Computers, And A Web Rant

May 23, 2025 by 1 Comment

We’re back in Europe for this week’s Hackaday podcast, as Elliot Williams is joined by Jenny List. In the news this week is the passing of Ed Smylie, the engineer who devised the famous improvised carbon dioxide filter that saved the Apollo 13 astronauts with duct tape.

Closer to home is the announcement of the call for participation for this year’s Hackaday Supercon; we know you will have some ideas and projects you’d like to share.

Interesting hacks this week include a new Mac Plus motherboard and Doom (just) running on an Atari ST, while a LoRa secure messenger and an astounding open-source Ethernet switch captivated us on the hardware front. We also take a dive into the Mouse programming language, a minimalist stack-based environment from the 1970s. Among the quick hacks are a semiconductor dopant you can safely make at home, and a beautiful Mac Mini based cyberdeck.

Finally, we wrap up with our colleague [Maya Posch] making the case for a graceful degradation of web standards, something which is now sadly missing from so much of the online world, and then with the discovery that ChatGPT can make a passable show of emulating a Hackaday scribe. Don’t worry folks, we’re still reassuringly meat-based.

Insert MP3 podcast link here.

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Hacking The 22€ BLE SR08 Smart Ring With Built-In Display

February 5, 2025 by 30 Comments

In the process of making everything ‘smart’, it would seem that rings have become the next target, and they keep getting new features. The ring that [Aaron Christophel] got his mittens on is the SR08, which appears to have been cloned by many manufacturers at this point. It’s got an OLED display, 1 MB Flash and a Renesas DA14585 powering it from a positively adorable 16 mAh LiPo battery.

The small scale makes it an absolute chore to reverse-engineer and develop with, which is why [Aaron] got the €35 DA14585 development kit from Renesas. Since this dev kit only comes with a 256 kB SPI Flash chip, he had to replace it with a 1 MB one. The reference PDFs, pinouts and custom demo firmware are provided on his GitHub account, all of which is also explained in the video.

Rather than hack the ring and destroy it like his first attempts, [Aaron] switched to using the Renesas Software Update OTA app to flash custom firmware instead. A CRC error is shown, but this can be safely ignored. The ring uses about 18 µA idle and 3 mA while driving the display, which is covered in the provided custom firmware for anyone who wants to try doing something interesting with these rings.

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