Open Source DC UPS Keeps The Low-Voltage Gear Going

December 22, 2023 by Dan Maloney 27 Comments

We all like to keep our network gear running during a power outage — trouble is, your standard consumer-grade uninterruptible power supply (UPS) tends to be overkill for routers and such. Their outlet strips built quickly get crowded with wall-warts, and why bother converting from DC to AC only to convert back again?

This common conundrum is the inspiration for [Walker]’s DC UPS design, which has some interesting features. First off, the design is open source, which of course invites tinkering and repurposing. The UPS is built for a 12 volt supply and load, but that obviously can be changed to suit your needs. The battery bank is a 4S3P design using 18650 cells, and that could be customized as well. There’s an ideal diode controller that prevents DC from back-feeding into the supply when the lights go out, and a really interesting synchronous buck-boost converter in place of the power management chip you’d normally see in a UPS. The converter chip takes a PWM signal from an RP2040; there’s also an ESP32 onboard for web server and UI duties as well as an STM32 to run the BMS. The video below discusses the design and shows a little of the build.

We’ve seen a spate of DC UPS designs lately, some more elaborate than others. This one has quite a few interesting chips that most of us don’t normally deal with, and it’s nice to see how they’re used in a practical design.

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A bald white man stands behind a table with an Apple II, a large green PCB, and a modular purple and black development board system. Atop the Apple II is what appears to be a smaller Apple II complete with beige case and brown fake keyboard.

Mini Apple IIe Now Fully Functional

December 5, 2023 by Navarre Bartz No comments

Here at Hackaday, we love living in a future with miniaturized versions of our favorite retrocomputers. [James Lewis] has given us another with his fully functional Apple IIe from the Mega II chip.

When we last checked in on the Mega IIe, it was only just booting and had a ways to go before being a fully functional Apple II. We really love the modular dev board he designed to do the extensive debugging required to make this whole thing work. Each of the boards is connected with jumper pins, which [Lewis] admits would have been better as edge connectors since he should’ve known he’d be unplugging and replugging them more than he’d like.

This modular prototyping system paid dividends late in the project when a “MEGA bug” threatened the stability of the entire system. Since it was confined to the keyboard PCB, [Lewis] was able to correct the error and, swapping for the third revision of the board, everything that had been crashing the system now ran.

There were still some issues going to the final unified PCB that nearly made him give up on the project, but perseverance paid off in the end. Combining vintage chips and multiple RP2040s isn’t for the feint of heart.

Now that you have a more conveniently-sized Apple II, why not teach it some new tricks like digital photography or ChatGPT?

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Tiny POV Turns Right Round For Volumetric Fun

December 3, 2023 by Dan Maloney 13 Comments

Just when you think the POV thing has run out of gas, along comes [mitxela] to liven things up. In this, he’s taken the whole persistence of vision display concept and literally spun up something very cool: a tiny volumetric “electric candle” display.

As he relates the story, the idea came upon him on a night out at the pub, which somehow led to the idea of an electric candle. Something on the scale of a tea light would fit [mitxela]’s fascination with very small and very interesting circuits, so it was off to the races. Everything needed — motor, LIR2450 coin cell, RP2040, and the vertical matrix of LEDs — fits into the footprint of the motor, which was salvaged from a CD drive. To avoid the necessity of finding or building a tiny slip-ring, he instead fixed everything to the back of the motor and attached its shaft to a Delrin baseplate.

The 8×10 array of surface-mount LEDs stands atop the RP2040 with the help of some enameled magnet wire, itself a minor bit of circuit sculpture. There’s also a 3D-printed holder for a phototransistor and IR LED, which form a sensor to trigger the display; you can see [mitxela] using a finger to turn the display off and move it back and forth. It goes without saying that these things always look better in person than they do in stills or even on video, but we still think it looks fantastic. There’s also a deep dive into generating volumetric data in the write-up, as well as an unexpected foray into the fluid dynamics calculations needed to create a realistic flame effect for the candle.

All in all, this is a fantastic if somewhat fragile project. We love the idea of putting this in a glass enclosure to make it look a little like a Nixie tube, too.

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PicoGUS: For All Your ISA Sound Card Needs

November 21, 2023 by Julian Scheffers 23 Comments

Sound cards used to be a big part of gaming machines in the 90s and 2000s but have largely gone extinct in the wake of powerful CPUs doing the sound themselves. Sound cards were expensive back then and, because the good ones weren’t very common, are expensive still for the retro gamer. But if you don’t need the real thing, [polpo] has you covered with his RP2040-based ISA sound card.

The PicoGUS, as he calls it, primarily serves to replace the Gravis UltraSound with modern components at a low cost. It uses the RP2040’s PIO to attach to an ISA bus and the RP2040’s dual-core power to synthesize the audio for its primary target, but also the AdLib (OPL2), CMS/Game Blaster and Tandy 3-Voice. [polpo] sells the PicoGUS on his Tindie store, but since it’s open source, you can of course just make your own.

Although “work-in-progress”, the PicoGUS is very useful to the right person and a perfect demonstration of how the RP2040’s PIO can be used to interface with almost any type of protocol.

Of couse, that’s not the only way to use the PIO, you can also create a CAN bus or even add another USB port.

A black motion system with two stepper motors. A green circuit board is fixed in a rotating cage in the center, and the entire assembly is on a white base atop a green cutting mat. Wires wind through the assembly.

Pi-lomar Puts An Observatory In Your Hands

November 20, 2023 by Navarre Bartz 5 Comments

Humans have loved looking up at the night sky for time immemorial, and that hasn’t stopped today. [MattHh] has taken this love to the next level with the Pi-lomar Miniature Observatory.

Built with a Raspberry Pi 4, a RPi Hi Quality camera, and a Pimoroni Tiny2040, this tiny observatory does a solid job of letting you observe the night sky from the comfort of your sofa (some assembly required). The current version of Pi-lomar uses a 16mm ‘telephoto’ lens and the built-in camera libraries from Raspbian Buster. This gives a field of view of approximately 21 degrees of the sky.

While small for an observatory, there are still 4 spools of 3D printing filament in the five different assemblies: the Foundation, the Platform, the Tower, the Gearboxes and the Dome. Two NEMA 17 motors are directed by the Tiny2040 to keep the motion smoother than if the RPi 4 was running them directly. The observatory isn’t waterproof, so if you make your own, don’t leave it out in the rain.

If you’re curious how we might combat the growing spectre of light pollution to better our nighttime observations, check out how blinking can help. And if you want to build a (much) larger telescope, how about using the Sun as a gravitational lens?

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The Birdy44 Keyboard Is Something To Crow About

October 18, 2023 by Kristina Panos 6 Comments

The funny thing about keyboard end game is that it usually involves more than one keyboard. Rare is the board that is great for both home and away. Having finished their dactyl build, [RalphCoder13] was looking to build something slimmer and more portable, and the Birdy44 was born.

This hand-wired beauty uses a pair of Waveshare RP2040 Zeros and features a pair of 40mm Cirque track pads that were salvaged from a Steam controller.

As you may have guessed, there are 44 Kailh Chocs that sit underneath a combination of MBK and 3D-printed keycaps. Our favorite part might be the tenting legs, which are optional and connect magnetically.

Part of portability is how you decide to carry the thing. You probably don’t want it naked and loose in your backpack if you can avoid it, right? To that end, he designed a nice little case for the halves. The original plan was to use magnets to hold them in place inside the topless case, but that didn’t work out so well, so he added wide elastic bands to stretch around the case.

Is this still not portable enough for you? Check out this folding split keyboard.

Via KBD

2023 Halloween Hackfest: Candy Basket Sees You Coming

October 14, 2023 by Kristina Panos 5 Comments

On Halloween, some people can’t or don’t want to open the door for various reasons. Maybe they have a cat that likes to escape every chance it gets, or maybe their favorite TV show is on during prime trick-or-treating time. Whatever the case, we think it’s perfectly acceptable to leave a bowl of candy outside the door, especially if there are electronics involved.

In this case, the bowl detects trick-or-treaters and candy eaters using an LD2410 60 GHz radar sensor and an RP2040. A light pipe shows orange when a person is detected, and switches over to green as they come closer, as if to say you may have candy now.

Nothing happens after that, but now that we think about it, it would be cool to add an MP3 decoder and a speaker to play a little witch cackle or something once they’ve had a chance to stick their hand in the bucket.

[Mike Kushnerik] actually designed the PCB a few months ago for non-Halloween purposes: some home automation projects. But then they were trying to think of something for Halloween, and this delightful light-up bucket came to mind. In addition to the RP2040 chip, there’s a 128 MB flash chip, a WS2812 LED, and a header for communicating with the radar sensor over UART. Be sure to check out the brief demo video after the break.

If you’d like to stand outside and give out candy, at least send it down a light-up slide or something.

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