Building A Wireless Fingerprint Authorization Device

July 3, 2026 by 12 Comments

Once upon a time, there was a bit of a fad for fingerprint authentication in laptops and desktop computers. It has long since faded, but [superdog] wanted just such a device for Linux and Mac machines. Thus, it was time to build one.

[superdog] designed the device, nicknamed immurok, as a tool for people who use external keyboards, and do lots of terminal work on Mac and Linux machines. Repeat password requests can interrupt one’s flow when hustling at the keys, so immurok was designed to ease this pain.

The device is based on a WCH CH592F microcontroller, which comes with Bluetooth connectivity out of the box. This allows immurok to connect wirelessly to the machine of your choice, advertising itself as a standard Bluetooth HID keyboard device. Fingerprint-wise, scanning is done with an R559S capacitive sensor, which verifies the match locally so there’s no transmitting biometric data anywhere. On the computer side, Linux is setup to use a CLI/TUI app plus PAM integration to handle authorization for system logins and sudo in the terminal. On the Mac platform, it’s used with a menu bar app, with PAM integration for admin prompts. There’s also a separate helper path for using it with the lock screen.

If you’re sick of entering your password all the time and wish unlocking your PC was more like unlocking your phone, this might be the project for you. We’ve seen similar projects before, too. If you’re whipping up fun gear for biometric auth, don’t hesitate to let us know on the tipsline.

Microdistillery For Microchemistry

July 3, 2026 by 17 Comments

Much like radio operators being encouraged to use the least possible amount of power to make a contact, chemists have a similar rule encouraging using the least amount of materials in experiments. Not only is this rooted in economics, but in safety as well; if something goes wrong it’s generally good if there’s not excess amounts of reactants. With modern techniques, though, it’s possible to bring experimental chemistry down to incredibly small scales, and [Marb’s lab] found that they needed a custom built still for these new, diminutive experiments.

The first step is to build the heating component of the still. This is provided with a few custom aluminum parts for the base and a pair of heaters originally meant for 3D printers, with the assembled unit wrapped in insulation. The heater accomodates a 25 mL round-bottom flask. Temperature control of the heating mantle is provided by a controller mounted to a DIN rail which receives power from a 24V power supply, and an additional temperature probe is added to measure the temperature of the distillate. A test run with water shows the small still quickly and efficiently evaporating the water up to a condenser.

Although building a still doesn’t have to be technically difficult, building something this small that’s effective and safe is a bit more challenging than a backyard moonshining operation. Scaling chemical reactions down can often be a challenge but is possible with the right mindset and equipment. We’ve seen miniaturization of many things that we might not have expected including hydrogen production, aluminum smelting, and even the construction of a microscope.

Continue reading “Microdistillery For Microchemistry” →

This KVM Runs A P4 Instead Of A Pi.

July 3, 2026 by 15 Comments

If you asked us to build you a KVM last week, we’d likely have reached for a Raspberry Pi. Now, thanks to [JonathanRowny], we’d seriously consider an ESP32-P4, because his IP KVM seems pretty capable.

He’s using the P4 hardware to its fullest, getting the supported 1080p graphics, and doing so in an interesting way– he’s got a commercial adapter board to try and translate HDMI signals to the camera input on his dev board. Conveniently enough, it’s the same ribbon-cable pinout as the RPi, which is not guaranteed by the CSI standard. Writing a driver to take that signal proved the hardest part– aside from the usual chip revision confusion that plagues this chip– and we can’t help but wonder if the client on the other side of the KVM-IP link might have an easier time doing the image processing that was required for a good image. Regardless, he’s got the code as it is now up on GitHub under the Apache license. 

As of this this writing, there’s no audio, and ironically for an ESP32 project networking is wired-only– but much more importantly, there is no security. So it’s a work in progress, but great to see the P4 in the wild doing something other than emulation. Not that we haven’t seen the P4 at work before–the Tanmatsu handheld also makes use of Expressif’s most powerful chip for a handy little terminal. Between the KVM and the handhelds, we cannot help but wonder how many of the projects that were once the provenance of a Pi will get squeezed into these overpowered microcontrollers. Sure, they can’t even match the original Pi in horsepower, never mind a modern Pi5, but how many times have you seen a Linux SBC seriously under-taxed in a project like this?

If you’re swapping Pi for P4– or doing anything else interesting– please let us know on the tips line.

Continue reading “This KVM Runs A P4 Instead Of A Pi.” →

Settling The Debate On Soldered Versus Crimped High-Current Connectors

July 3, 2026 by 71 Comments

For some reason there’s heated debate around the topic of whether high current carrying wiring ought to use crimped or soldered connections, even though the industry standard is to crimp everything. As a practical demonstration of why this is the case, [Will Prowse] set up a test involving a rig capable of dispensing a few hundred amps through both a crimped and a soldered copper cable.

Prior to making things go spicy, [Will] made sure to check the resistance of the two cables, noting that the soldered version had significantly lower resistance than the crimped connectors. This could be one metric that proponents of soldered connectors can point to as a benefit.

Of course, the main benefit of crimping is that you create a cold weld if crimped properly, which is a sold-state welding process that effectively blends two metal surfaces together. This is also why wire wrap is generally considered to be so very reliable, as it creates a gas-free, solid connection that does not rely on a softer, dissimilar material like solder to hold things together. Of note here is also that the cold weld process tends to continue for a while, so this kind of connection is likely to get better over time.

In the subsequent testing this difference is demonstrated quite well, especially when both cables are subjected to the sort of mechanical abuse that would be expected in an installation, such as vibrations and direct impacts. Here the soldered connections quickly begin to fail, resulting in one soldered connector even unsoldering itself due to heat development. Ultimately cold welding is simply superior over relying on a flimsy and capricious interface of intermetallic compounds.

Continue reading “Settling The Debate On Soldered Versus Crimped High-Current Connectors” →

Hackaday Podcast Episode 376: Modern Retro Projects, Retro Modern Projects, And The Teen Years For 3D Printing

July 3, 2026 by 2 Comments

Hackaday’s Elliot Williams and Al Williams were in a retro mood this week. There was a new ‘486 computer, a new mechanical TV, and a USB stick with a magnetic personality. Can you watch YouTube on a Game Boy? Maybe.

For the can’t miss articles, this week, Elliot and Al reflected on the awkward phase of 3D printers when they transformed from being expensive commercial machines, to where they are now. Meanwhile, Al was interested in how airplanes know how fast they are going. Along the way, there were musical hacks, precision machine tools, and a quantum 8 ball.

Check out the links if you want to follow along, and as always, tell us what you think about this episode in the comments! Or write or record something for our mailbag segment.

Direct download in authentic retro DRM-free MP3.

Where to Follow Hackaday Podcast

Places to follow Hackaday podcasts:

Continue reading “Hackaday Podcast Episode 376: Modern Retro Projects, Retro Modern Projects, And The Teen Years For 3D Printing” →

The Organ That Forgot To Use Transistors

July 3, 2026 by 11 Comments

When we think of 1960s synthesizers it’s usual to imagine instruments with vast arrays of controls and patch cables for configuring their many filters, oscillators, and other parameters. They created the templates for much of what we know today as electronic music.

In all the rush to look at full-blown synths though, it’s easy to forget their more mundane cousin, the electric organ. These instruments graced many a ’60s suburban home or church hall, and [Emma Repairs] has an interesting one. It’s a Philips Philicordia, and it’s sent us here at Hackaday down one of those rabbit holes when we should really be writing.

The instrument is a relatively straightforward single voice electric organ on the outside, but under the hood it’s a different matter. In an age when the transistor was revolutionizing electronic music, the folks in Eindhoven designed this one using tubes. There are a set of conventional enough tubes performing the role of amplifiers and oscillators, but the real party piece of this unit is the array of neon tube dividers. A neon bulb can be used as a switching element, and in those days when affordable digital logic chips were several years away, it made sense to use them in digital circuits.

The inside of the Philicordia is a feast of vintage Philips parts that will be instantly familiar to anyone who’s worked on Western European electronics of this era. The exterior design of the instrument screams understated early-1960s cool, and after she’s introduced it you can hear her playing it in the video below. Further down that rabbit hole we found that one of these instruments provided the distinctive organ sound on Chris Montez’s 1962 hit Let’s Dance, so they weren’t all uncool.

Continue reading “The Organ That Forgot To Use Transistors” →