flipper zero uv sensor

A UV Meter For The Flipper Zero

May 19, 2025 by 6 Comments

We all know UV radiation for its contributions to getting sunburned after a long day outside, but were you aware there are several types different types of UV rays at play? [Michael] has come up with a Flipper Zero add on board and app to measure these three types of radiation, and explained some of the nuances he learned about measuring UV along the way.

At the heart of this project is an AS7331 sensor, it can measure the UV-A, UV-B, and UV-C radiation values that the Flipper Zero reads via I2C. While first using this chip he realized to read these values is more complex than just querying the right register, and by the end of this project he’d written his own AS7331 library to help retrieve these values. There was also a some experimenting with different GUI designs for the app, the Flipper Zero screen is only 128x64px and he had a lot of data to display. One feature we really enjoyed was the addition of the wiring guide to the app, if you install this Flipper Zero app and have just the AS7331 sensor on hand you’ll know how to hook it up. However if you want he also has provided the design files for a PCB that just plugs into the top of the Flipper Zero.

Head over to his site to check out all the details of this Flipper Zero project, and to learn more about the different types of UV radiation. Also be sure to let us know about any of your Flipper Zero projects.

Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Wafer-Thin Keyboard

May 19, 2025 by 8 Comments

The mikecinq, an incredibly slim keyboard.
Image by [dynam1keNL] via reddit
But sir! I can’t believe I missed [dynam1keNL]’s initial flat offering from about a year ago, the mikefive, which came about when he and some friends ordered switches directly from Kailh and Kailh were like, do you want to try these even lower-profile PG1316 laptop switches? It’s called the mikefive because it’s 5 mm thick.

That’s okay, though, because now you’re caught up and I can talk about his latest keyboard, the mikecinq. The inspiration for this one includes the aesthetics of Le Chiffre and the slimness of Le Oeuf. As you’ll see in the gallery, the top is ever-so-slightly slanted downward from the top.

You can see it really well in the second picture — the top row is flush with the case, and the keys gradually get taller toward the thumb clusters. All [dynam1keNL] really had to do was 3D model the new case and screw in the PCB from his daily driver mikefive.

Image by [dynam1keNL] via reddit
[dynam1keNL] ultimately found it nice and comfy, especially for the thumbs, but decided to take it one step further and designed a new switch footprint. Why? The PG1316s are surface-mount with contacts below the switch, so you really need a hotplate or oven to mount them.

So in order to deal with this, he made a dedicated mikecinq PCB with big cutouts with castellated holes beneath each switch. Now, the switch contacts are accessible from underneath and can be soldered with an iron.

You may have noticed that the mikefive production files are not available on GitHub — that’s because it was recently licensed and will be available soon. But if you want production files for the mikecinq, let him know in the comments.

Continue reading “Keebin’ With Kristina: The One With The Wafer-Thin Keyboard” →

The Nightmare Of Jailbreaking A ‘Pay-To-Ride’ Gotcha Ebike

May 19, 2025 by 36 Comments

Theoretically bicycle rental services are a great thing, as they give anyone the means to travel around comfortably without immediately having to rent a car, hail a taxi or brave whatever the local public transport options may be. That is until said services go out of business and suddenly thousands of increasingly more proprietary and locked-down e-bikes suddenly are at risk of becoming e-waste. So too with a recent acquisition by [Berm Peak] over at YouTube, featuring a ‘Gotcha’ e-bike by Bolt Mobility, which went AWOL back in 2022, leaving behind thousands of these e-bikes.

So how hard could it be to take one of these proprietary e-bikes and turn it into a run-off-the-mill e-bike for daily use? As it turns out, very hard. While getting the (36V) battery released and recharged was easy enough, the challenge came with the rest of the electronics, with a veritable explosion of wiring, the Tongsheng controller module and the ‘Gotcha’ computer module that locks it all down. While one could rip this all out and replace it, that would make the cost-effectiveness of getting one of these go down the drain.

Sadly, reverse-engineering the existing system proved to be too much of a hassle, so a new controller was installed along with a bunch of hacks to make the lights and new controller work. Still, for $75 for the bike, installing new electronics may be worth it, assuming you can find replacement parts and got some spare hours (or weeks) to spend on rebuilding it. The bike in the video costed less than $200 in total with new parts, albeit with the cheapest controller, but maybe jailbreaking the original controller could knock that down.

Continue reading “The Nightmare Of Jailbreaking A ‘Pay-To-Ride’ Gotcha Ebike” →

Remembering The ISP That David Bowie Ran For Eight Years

May 19, 2025 by 14 Comments

The seeds of the Internet were first sown in the late 1960s, with computers laced together in continent-spanning networks to aid in national defence. However, it was in the late 1990s that the end-user explosion took place, as everyday people flocked online in droves.

Many astute individuals saw the potential at the time, and rushed to establish their own ISPs to capitalize on the burgeoning market. Amongst them was a famous figure of some repute. David Bowie might have been best known for his cast of rock-and-roll characters and number one singles, but he was also an internet entrepreneur who got in on the ground floor—with BowieNet.

Continue reading “Remembering The ISP That David Bowie Ran For Eight Years” →

A white control box is shown in the foreground. The box has an LCD display, eight button, and two barbed fittings for flexible tubing.

Using Pitot Tubes For More Than Aircraft

May 19, 2025 by 7 Comments

When we hear the words “pitot tube,” we tend to think more of airplanes than of air ducts, but [Franci Kopač]’s guide to pitot tubes for makers shows that they can be a remarkably versatile tool for measuring air speed, even in domestic settings.

A pitot tube is a tube which faces into an air flow, with one hole at the front of the tube, and one on the side. It’s then possible to determine the air speed by measuring the pressure difference between the side opening and the end facing into the wind. At speeds, temperatures, and altitudes that a hacker’s likely to encounter (i.e. not on an airplane), the pressure difference is pretty small, and it’s only since the advent of MEMS pressure sensors that pitot tubes became practical for amateurs.

[Franci]’s design is based on a Sensiron SDP differential pressure sensor, a 3D-printed pitot tube structure, some tubing, and the microcontroller of your choice. It’s important to position the tube well, so that it doesn’t experience airflow disturbances from other structures and faces straight into the air flow. Besides good positioning, the airspeed calculation requires you to know the air temperature and absolute pressure.

[Franci] also describes a more exotic averaging pitot tube, a fairly simple variation which measures air speed in cavities more accurately. He notes that this provides a more inexpensive way of measuring air flow in ducts than air conditioning flow sensors, while being more resilient than propeller-based solutions – he himself used pitot tubes to balance air flow in his home’s ventilation. All of the necessary CAD files and Arduino code are available on his GitHub repository.

If you’re looking for a more conventional duct flow meter, we’ve covered one before. We’ve even seen a teardown of a pitot tube sensor system from a military drone.

MiSTER Multisystem 2 on a wooden table

MiSTer For Mortals: Meet The Multisystem 2

May 19, 2025 by 21 Comments

If you’ve ever squinted at a DE10-Nano wondering where the fun part begins, you’re not alone. This review of the Mr. MultiSystem 2 by [Lee] lifts the veil on a surprisingly noob-friendly FPGA console that finally gets the MiSTer experience out of the tinker cave and into the living room. Developed by Heber, the same UK wizards behind the original MultiSystem, this follow-up console dares to blend flexibility with simplicity. No stack required.

It comes in two varieties, to be precise: with, or without analog ports. The analog edition features a 10-layer PCB with both HDMI and native RGB out, Meanwell PSU support, internal USB headers, and even space for an OLED or NFC reader. The latter can be used to “load” physical cards cartridge-style, which is just ridiculously charming. Even the 3D-printed enclosure is open-source and customisable – drill it, print it, or just colour it neon green. And for once, you don’t need to be a soldering wizard to use the thing. The FPGA is integrated in the mainboard. No RAM modules, no USB hub spaghetti. Just add some ROMs (legally, of course), and you’re off.

Despite its plug-and-play aspirations, there are some quirks – for example, the usual display inconsistencies and that eternal jungle of controller mappings. But hey, if that’s the price for versatility, it’s one you’d gladly pay. And if you ever get stuck, the MiSTer crowd will eat your question and spit out 12 solutions. It remains 100% compatible with the MiSTer software, but allows some additional future features, should developers wish to support them.

Want to learn more? This could be your entrance to the MiSTer scene without having to first earn a master’s in embedded systems. Will this become an alternative to the Taki Udon announced Playstation inspired all-in-one FPGA console? Check the video here and let us know in the comments. Continue reading “MiSTer For Mortals: Meet The Multisystem 2” →

In Memory Of Ed Smylie, Whose Famous Hack Saved The Apollo 13 Crew

May 18, 2025 by 30 Comments

Some hacks are so great that when you die you receive the rare honor of both an obituary in the New York Times and an in memoriam article at Hackaday.

The recently deceased, [Ed Smylie], was a NASA engineer leading the effort to save the crew of Apollo 13 with a makeshift gas conduit made from plastic bags and duct tape back in the year 1970. [Ed] died recently, on April 21, in Crossville, Tennessee, at the age of 95.

This particular hack, another in the long and storied history of duct tape, literally required putting a square peg in a round hole. After an explosion crippled the command module the astronauts needed to escape on the lunar excursion module. But the lunar module was only designed to support two people, not three.

The problem was that there was only enough lithium hydroxide onboard the lunar module to filter the air for two people. The astronauts could salvage lithium hydroxide canisters from the command module, but those canisters were square, whereas the canisters for the lunar module were round.

[Ed] and his team famously designed the required adapter from a small inventory of materials available on the space craft. This celebrated story has been told many times, including in the 1995 film, Apollo 13.

Thank you, [Ed], for one of the greatest hacks of all time. May you rest in peace.

Header: Gas conduit adapter designed by [Ed Smylie], NASA, Public domain.