Makers and hardware hackers have been collecting disposable vapes for some time now, usually to salvage their batteries or the unique displays many models now come with. But you can also repurpose them for other ends, such as playing music. [Becky Stern]’s vape synth is a perfect example of this.

The build started with an ElfBars BC5000 vape. [Becky] notes there may be similar models under different names out there that would work just as well. The vape is effectively gutted for parts, with the LiPo cell, USB charging board, and the low-pressure sensor the main things that remain. These parts are combined with a drop-in 555 synthesizer circuit complete with speaker, which has its pitch controlled by a series of six photoresistors. When the low pressure sensor is triggered by inhalation, the 555 circuit is triggered, and operates at a pitch depending on the resistance of the photoresistor stack.

The output of the vape synth is kind of shrill, and frankly a little bit annoying — which is somehow rather fitting for what it is. If you want to make a better-sounding synth at home, we’ve featured such projects, you’re just unlikely to fit them entirely within the housing of a disposable vape.

youtube.com/embed/TyoWpvDcDs0?…

hackaday.com/2026/03/24/dispos…

Io i vibe coder li capisco.

spreaker.com/episode/dk-10x25-…

In the blue corner, we have the VENUS FLYTRAP! In the red corner, we have the underdog of the century, AN ENTIRE PARTICLE ACCELERATOR. Yes, you read that right. When you have a particle accelerator, it’s only second nature to throw anything you can into it. That’s why [Electron Impressions] put a poor fly-eating trap into their accelerator.
Chloride and potassium ions leaving cause osmotic pressure in neighboring cells
The match-up isn’t quite as arbitrary as it might seem at first. The flytrap’s main mechanism of trapping and digesting insects relies heavily on intracellular ion movement. Many cells along the inside of the trap have hair-activated calcium channels that respond to a fly landing on its surface. This ion movement then creates an action potential, which propagates along the entire surface, triggering closing. As the potential moves across different cells, other ions leave and create osmotic pressure. This pressure is what creates the mechanical movement.

Of course, this makes it no surprise when the plant finds itself under the ionizing radiation that every single head closes at once. While this is a cool demonstration, there is a slight side effect of killing every single cell by ripping apart the trap’s DNA.

Well, who would have guessed that the underdog accelerator would have won… Anyways, the DNA being ripped apart is far from ideal for repeatability. If you want to learn more about genetic features that SHOULD be repeated, then make sure to check out the development of open-source insulin!

youtube.com/embed/CZIhu9Jiyw4?…

hackaday.com/2026/03/23/venus-…

Supercapacitors rely mostly on double-layer capacitance to bridge the divide between chemical batteries and traditional capacitors, but they come with a number of weaknesses. Paramount among these are their relatively low voltage of around 2.7 V before their electrolyte begins to decompose, as well as their relatively high rates of self-discharge. Here a new design using lignin-derived porous carbon electrodes and a fluorinated diluent was demonstrated by [Shichao Zhang] et al., as published in Carbon Research, that seems to address these issues.

Most notable are the relatively high voltage of 4 V, an energy density of 77 Wh/kg and a self-discharge rate that’s much slower than that of conventional supercapacitors. In comparison with these supercapacitors, these demonstrated versions are also superior in terms of recharge cycles with 90% of capacity remaining after 10,000 cycles, which together with their much higher energy density should prove to be quite useful.

This feat is accomplished by using lignin as the base for the carbon electrodes to make a highly porous surface, along with the new electrolyte formulation consisting of alithium salt (LiBF₄) dissolved in sulfolane with TTE as a non-solvating diluent. The idea of using lignin-derived carbon for such a purpose has previously been pitched by [Jia Liu] et al. in 2022 and [Zhihao Ding] in 2025, with this seemingly one of the first major applications we may be seeing.

Although the path towards commercialization from a lab-assembled prototype is a rough one, we may be seeing some of these improvements come to supercapacitors near you sooner rather than later.

hackaday.com/2026/03/23/low-se…

This week, the European Parliament faces a decisive vote on whether the indiscriminate scanning of private chats and emails by US tech companies (Chat Control 1.0) will be allowed to continue. After Parliament voted on 11 March to replace blanket mass surveillance with targeted monitoring of suspects — thereby protecting the confidentiality of digital correspondence — EU member state governments let the trilogue negotiations fail by refusing to compromise in substance.

Now, in an unprecedented manoeuvre, the conservative EPP group is attempting to force a repeat vote on Thursday (26 March) to overturn the Parliament’s principled decision and keep indiscriminate chat scanning in place. A preliminary vote on Wednesday will determine whether this repeat vote goes ahead or is struck from the agenda.

Digital rights expert and former MEP Patrick Breyer outlines the urgently needed change of strategy:

“Indiscriminate Chat Control is like trying to mop up water while the faucet is still running. It is technologically obsolete and a proven failure in criminal justice terms. Flooding our police forces each year with hundreds of thousands of hits from unreliable US algorithms — most of them either false positives or long-known duplicates — does not rescue a single child from ongoing abuse. This data deluge ties up massive resources that are desperately needed for undercover investigations into actual abuse networks. To genuinely protect children online, we need a paradigm shift: providers must be required to prevent cybergrooming through safe app design and strict default settings. Illegal material on the open internet and darknet must be proactively tracked down and removed at source. That is what truly protects children.”

Background: What exactly expires on 3 April

An EU interim regulation (2021/1232), set to expire on 3 April, currently permits US corporations such as Meta to carry out indiscriminate mass scanning of private messages on a voluntary basis. Three types of chat control are authorised: scanning for already known images and videos (so-called hash scanning, which generates over 90% of reports); automated assessment of previously unknown images and videos; and automated analysis of text content in private chats.

The AI-based analysis of unknown images and texts is extremely error-prone. But the indiscriminate mass scanning for known material — proposed by socialists and liberals — is highly controversial, too: beyond the unreliability of the algorithms documented by researchers, these scans rely on opaque foreign databases rather than European criminal law. The algorithms are blind to context and lack of criminal intent (e.g. consensual sexting between teenagers). As a result, vast numbers of private but criminally irrelevant chats are exposed.

In the run-up to the vote, US tech corporations, foreign-funded lobby groups, and law enforcement agencies are flooding public discourse with warnings about an alleged “legal gap.” A comparison of their claims with internal documents, scientific studies, and the voices of child protection experts and actual abuse survivors, however, reveals an entirely different picture.

Disinformation Narratives of Chat Control Proponents — and the Facts

Disinformation 1: “The European Parliament is to blame for the collapse of negotiations and is putting children at risk.”
(Claimed by the lobby alliance ECLAG and US tech companies)

• Fact: It was the EU Council of Ministers that deliberately let the trilogue negotiations fail, for tactical reasons.
• Evidence: Leaked Council cables, classified as restricted, reveal that EU member states showed no willingness to compromise, fearing that any concession could set a precedent for the permanent Chat Control 2.0 regulation. The classified minutes from 13 March show that the Cypriot Presidency already anticipated failure before the final trilogue round, noting it did “not expect to reach an agreement” with the lack of a new mandate given by member states. A majority including Hungary, Belgium, Sweden, Spain, Latvia, Slovakia, Malta, Estonia, Slovenia, Romania and Germany were unwilling to make any concessions on scope. Only a small minority of governments including France and Ireland agreed to the Presidency’s proposal to phase out at least the most error-prone text scanning in search of “grooming”. The Netherlands showed itself “completely flexible”, and Italy had long before criticised the scope of scans and demanded “prior authorization of detection activities by [public] authorities”.
• Parliament’s lead negotiator, Birgit Sippel (S&D), sharply criticised the Council after the breakdown: “with their lack of flexibility, Member States have deliberately accepted that the interim regulation will expire in April.”

Disinformation 2: “Without indiscriminate Chat Control, law enforcement will be flying blind.”
(Claimed by law enforcement officials across the EU)

• Fact: Targeted telecommunications surveillance based on concrete suspicion and a judicial warrant remains fully available after 3 April, as does the bulk scanning of public posts and hosted files. User reports also remain possible. The real problem for authorities is a flood of false leads and a systemic refusal to remove material from the internet.
• Evidence — investigative chaos: According to Germany’s Federal Criminal Police Office (BKA), nearly 50% of chat control reports are criminally irrelevant. This flood of data waste ties up massive resources desperately needed for targeted, undercover investigations into real abuse networks. Where investigations are opened, German crime statistics show that around 40% of suspects are minors themselves, often acting without criminal intent or in consensual situations. The Federation of German Criminal Investigators (BDK) warns that this mass surveillance produces “a flood of tips… often without any actual investigative lead.” Meanwhile, Europol and German authorities systematically refuse to proactively have abuse material removed from the internet, as investigative reporting by ARD/STRG_F has revealed — images and videos remain online despite authorities being fully able to have them taken down, even as they demand ever more surveillance powers.
• Evidence — failure to protect children: Mass scanning for already known images does not stop ongoing abuse and does not rescue children in acute danger. According to the European Commission’s own evaluation report, no measurable link can be established between the mass surveillance of private messages and actual convictions. Yet the Commission and Council demand the extension of a measure whose effectiveness they themselves cannot demonstrate.
• Evidence — risk of annulment in court: The European Data Protection Supervisor (EDPS) stresses that any solution used to detect illegal content must be targeted and not indiscriminate. The Council’s own legal service concluded in 2023 concerning the proposal for a permanent regulation (CSAR): “the detection order regime provided for by the proposed Regulation as regards interpersonal communications entails a serious risk that it would be found to compromise the essence of the rights to privacy and data protection enshrined in Article 7 and 8 of the Charter, in so far as it would seek to authorise access on a generalised basis, through automated and systemic screening surveillance, to the content of electronic communications and personal data of all users of a specific service, irrespective of their direct or indirect link with child sexual abuse criminal activities” (para 58)

Disinformation 3: “The scanning technology deployed is highly precise and protects privacy.”
(Claimed by Meta, Google, Microsoft, Snap, TikTok)

• Fact: The technology is an ineffective legacy system, error-prone, and destructive to the security of private communications.
• Evidence — an obsolete model: Offenders can effortlessly switch to secure messengers where no chat control takes place. Due to the increasing adoption of end-to-end encryption by providers, the number of chats reported to police has already dropped by 50% since 2022. Most recently, only 36% of reports from US companies originated from the chat control of private messages, while social media platforms and cloud storage services are becoming increasingly relevant. Rather than investing in targeted investigative work, the Council clings to a dying surveillance model.
• Evidence — unreliability: A recent international research paper documents the structural weaknesses of the industry standard PhotoDNA. The software is unreliable: criminals can make illegal images invisible through minimal alterations (e.g. adding a border), while innocent citizens can easily be falsely flagged. In a November 2025 open letter, leading IT researchers (including from the universities of Aarhus, Leuven, and ETH Zurich) warned: “False positives seem unavoidable.” According to an open letter by a coalition of more than 40 civil liberties organisations and professional associations (including Europe’s leading digital rights groups), the Commission’s own evaluation report confirms the measure’s failure: the US algorithms deployed show error rates of 13 to 20 percent. Of the billions of messages scanned, only 0.0000027 percent were actually illegal material.

Disinformation 4: “The call for Chat Control comes primarily from victims and civil society.”
(Suggested by the ECLAG campaign)

• Fact: Actual survivors are taking legal action against Chat Control. The real driving force behind the campaign is a network of tech companies and lobby organisations funded by governments and non-European foundations.
• Evidence — survivors speak out: Survivors of sexualised violence are fighting back. Alexander Hanff, a survivor and privacy advocate, writes: “As a survivor, I depend on confidential communication to find support and report crimes. Taking away our right to privacy means further harming us.” Dorothée Hahne of the survivors’ association MOGIS e.V. warns: “We see our safe spaces destroyed.” To preserve safe spaces for victims, a survivor from Bavaria is currently suing with the support of the Society for Civil Rights (GFF) against Meta’s scanning of his chats. The civil society coalition also warns that indiscriminate scanning dangerously undermines professional confidentiality for lawyers, doctors, and therapists.
• Evidence — lobbying: Who truly benefits from this legislation was exposed in an investigative report by Balkan Insight. The US organisation Thorn, which sells scanning software to public authorities, invests hundreds of thousands of euros annually in EU lobbying. ECLAG members are supported by tech corporations and the non-European Oak Foundation.

The Alternative to Surveillance Overreach: “Security by Design”

The European Parliament advocates a genuine paradigm shift, supported by civil society, survivor networks, and IT security experts: instead of indiscriminate mass surveillance of private communications using error-prone US algorithms, chat and messaging services should be “Secure by Design.” This includes:

1. Strict default settings and protective mechanisms (Security by Design) to make cybergrooming technically harder from the outset and prevent the creation of CSAM.
2. Targeted telecommunications surveillance based on judicially confirmed suspicion.
3. Proactive search by a new EU Center and immediate takedown obligations for providers and law enforcement on the open internet and darknet — removing illegal material at source.

Call to Action

Civil liberties advocates are urging citizens across Europe to contact their MEPs directly ahead of the decisive votes on Wednesday and Thursday. Through the campaign page fightchatcontrol.eu, MEPs can be called upon to reject the undemocratic motion for a repeat vote and to uphold the fundamental right to confidential correspondence.

Breyer warns:

“When a democratic decision is put to a vote repeatedly until the desired outcome is achieved, Parliament itself is devalued. This approach sets a dangerous precedent. It undermines the reliability of democratic processes and sends the signal that majorities only count when they are politically convenient. The responsible actors are damaging not only trust in the European institutions, but the very foundations of democracy.”

On Tuesday, EU governments will strategise in a restricted format and behind closed doors on the issue.

Citizens can contact their representatives via: fightchatcontrol.eu

patrick-breyer.de/en/the-battl…

Patrick Breyer

2026-03-10 14:34:07

🇪🇺 1/7 🌍 Foreign-funded lobby groups from outside the EU are pushing #ChatControl with misleading propaganda. They want to #PassTheLaw to scan your chats, but who are they and who's paying them? Let's expose the network.
Thread 👇

The Z80 has been gone a couple of years now, but it’s very much not forgotten. Still, the day when new-old-stock and salvaged DIP-40 packaged Z80s will be hard to come by is slowly approaching, and [eaw] is going to be ready with the picoZ80 project.

You can probably guess where this is going: an RP2350B on a DIP-40 sized PCB can easily sit on the bus and emulate a Z80. It can do so with only one core, without breaking a sweat. That left [eaw] a second core to play with, allowing the picoZ80 to act as a heck of an accelerator, memory expander, USB host, disk emulator– you name it. He even tossed in an ESP32 co-processor to act as a WiFi, Bluetooth, and SD-card controller to use as a virtual, wirelessly accessible disk drive.

The onboard ram that comes with an RP2350B would be generous by 1980s standards, but [eaw] bumped that up with an 8 MB SPRAM chip–accessed in 64 pages of 64 kB each, naturally. If more RAM than a very pricey hard drive wasn’t luxury enough, there’s also 16 MB of flash memory available. That’s configured to store ROM images that are transferred to the RAM at boot– the virtual Z80 isn’t grabbing from the flash at runtime in [eaw]’s architecture, because apparently there are limits to how much he wants to boost his retro machines.

[eaw] has the PCB fab do all the fiddly assembly these days. Earlier versions were hand-soldered to his credit.There are already drivers to use in certain Z80 systems. You can of course configure it as a bare Z80 with no machine-specific emulation, or set up the picoZ80 with the “persona” of a classic Z80 machine. So far [eaw] has tried this on an RC2014 homebrew computer, as well as Sharp MZ-80A– which we’ve seen here before, in miniature–and Sharp MZ-700. The Sharp drivers are still works in progress, after which the Amstrad PCW8256/Tatung TC01 is apparently next. We’ve seen Amstrad PCWs here a time or two as well, come to think of it.

If somehow you missed it, the venerable Z80 only hit EOL in 2024, so supplies won’t be drying up any time soon. This hack is really more about the quality-of-life addons this allows. Come back in a decade, and we’ll see if the RP2350 lasts longer than the stack of NOS Z80s.

hackaday.com/2026/03/23/picoz8…

We don’t usually speculate on the true identity of the hackers behind these projects, but when [TN666]’s accoustic drone-detector crossed our desk with the name “Batear”, we couldn’t help but wonder– is that you, Bruce? On the other hand, with a BOM consisting entirely of one ESP32-S3 and an ICS-43434 I2S microphone, this isn’t exactly going to require the Wayne fortune to pull off. Indeed, [TN666] estimates a project cost of only 15 USD, which really democratizes drone detection.
It’s not a tuba– Imperial Japanese aircraft detector being demonstrated in 1932. Image Public Domain via rarehistoricalphotos.com
The key is what you might call ‘retrovation’– innovation by looking backwards. Most drone detection schema are looking to the ways we search for larger aircraft, and use RADAR. Before RADAR there were acoustic detectors, like the famous Japanese “war tubas” that went viral many years ago. RADAR modules aren’t cheap, but MEMS microphones are– and drones, especially quad-copters, aren’t exactly quiet. [TN666] thus made the choice to use acoustic detection in order to democratize drone detection.

Of course that’s not much good if the ESP32 is phoning home to some Azure or AWS server to get the acoustic data processed by some giant machine learning model. That would be the easy thing to do with an ESP32, but if you’re under drone attack or surveillance it’s not likely you want to rely on the cloud. There are always privacy concerns with using other people’s hardware, too. [TN666] again reached backwards to a more traditional algorithmic approach– specifically Goertzel filters to detect the acoustic frequencies used by drones. For analyzing specific frequency buckets, the Goertzel algorithm is as light as they come– which means everything can run local on the ESP32. They call that “edge computing” these days, but we just call it common sense.

The downside is that, since we’re just listening at specific frequencies, environmental noise can be an issue. Calibration for a given environment is suggested, as is a foam sock on the microphone to avoid false positives due to wind noise. It occurs to us the sort physical amplifier used in those ‘war tubas’ would both shelter the microphone from wind, as well as increase range and directionality.

[TN] does intend to explore machine learning models for this hardware as well; he seems to think that an ESP32-NN or small TensorFlow Lite model might outdo the Goertzel algorithm. He might be onto something, but we’re cheering for Goertzel on that one, simply on the basis that it’s a more elegant solution, one we’ve dived into before. It even works on the ATtiny85, which isn’t something you can say about even the lightest TensorFlow model.

Thanks to [TN] for the tip. Playboy billionaire or not, you can send your projects into the tips line to see them some bat-time on this bat-channel.

hackaday.com/2026/03/23/acoust…

Graphics calculators are one of those strange technological cul-de-sacs. They rely on outdated technology and should not be nearly as expensive as they are, but market effects somehow keep prices well over $100 to this day. Given that fact, you might like to check out an open-source solution instead.

NumOS comes to us from [El-EnderJ]. It’s a scientific and graphic calculator system built to run on the ESP32-S3 with an ILI9341 screen. It’s intended to rival calculators like the Casio fx-991EX ClassWiz and the TI-84 Plus CE in terms of functionality. To that end, it has a full computer algebra system and a custom math engine to do all the heavy lifting a graphic calculator is expected to do, like symbolic differentiation and integration. It also has a Natural V.P.A.M-like display—if you’re unfamiliar with Casio’s terminology, it basically means things like fractions and integrals are rendered as you’d write them on paper rather than in uglier simplified symbology.

If you’ve ever wanted a graphics calculator that you could really tinker with down to the nuts and bolts, this is probably a great place to start. With that said, don’t expect your local school or university to let you take this thing into an exam hall. They’re pretty strict on that kind of thing these days.

We’ve seen some neat hacks on graphics calculators before, like this TI-83 running CircuitPython. If you’re doing your own magic with these mathematical machines, don’t hesitate to notify the tips line.

hackaday.com/2026/03/23/build-…

If you’ve ever run a game server or used BitTorrent, you probably know that life is easier if your router supports UPnP (Universal Plug and Play). This is a fairly old tech — created by a standards group in 1999 — that allows a program to open an incoming port into your home network. Of course, most routers let you do this manually, but outside of the Hackaday universe, most people don’t know how to log into their routers, much less how to configure an open UDP port.

I recently found myself using a temporary setup where I could not access the router directly, but I needed some open ports. That got me thinking: if a program can open a port using UPnP, why can’t I? Turns out, of course, you can. Maybe.

Caveats

The first thing, of course, is that you need your firewall open, but that’s true no matter how you open up the router. If the firewall is in the router, then you are at the mercy of the router firmware to realize that if UPnP opens something up, it needs to open the firewall, too.

You might think, “Of course it will do that.” However, I’ve found there is a lot of variation in the firmware from different vendors, and if you aren’t in control of the router, it is more likely to have buggy firmware.

The other caveat is that the router needs UPnP enabled; if it isn’t and you have to get into it anyway, you might as well set up port forwarding in the usual way. I was in luck. The router I was behind had UPnP turned on.

In Theory

There are several libraries aimed at working with UPnP and many of them come with simple test clients. I decided to install miniupnpd, which has the upnpc utility. You don’t have to be root to run it. In theory, it should be very simple to use. You can use -l to list all the router’s current UPnP ports. The -a option adds a port, and -d deletes it. There are a few other options, but that covers most of the common use cases.

So, to open external port 2222 to port 22 on 192.168.1.133 you should be able to say:
upnpc -e 'HaD Test' -a 192.168.1.133 22 2222 tcp 3600
The -e option lets us make up a creative title for the mapping. The 3600 is the number of seconds you need the port open. Easy, right? Well, of course not.

Under the Hood

UPnP covers several different areas, including IP assignment and streaming media. However, the part of it we are using is for NAT traversal. Your router identifies as an Internet Gateway Device that other UPnP-aware programs can locate.

Unfortunately, there are two versions of the gateway device specification, and there are many compatibility problems. You are also at the mercy of the vendor’s correct interpretation of the spec.

UPNP has been known to be a security risk. In 2011, a tool appeared that let some UPnP devices map ports when asked from outside your network. Easy to imagine how that could be a bad thing.

UPNP devices advertise services that others can use, and, hopefully, your router advertises that it is a gateway. The advertisement itself doesn’t tell you much. But it does let you fetch an XML document that describes the device.

For example, part of my XML file looks like this:
11urn:schemas-upnp-org:device:InternetGatewayDevice:1OpenWRT routerOpenWRT
openwrt.org/OpenWRT routerOpenWRT router1
openwrt.org/00000000uuid:00000…
urn:schemas-upnp-org:service:Layer3Forwarding:
1urn:upnp-org:serviceId:L3Forwarding1/L3F.xml/ctl/L3F/evt/L3Furn:
schemas-upnp-org:device:WANDevice:1WANDeviceMiniUPnPhttp://miniupnp.free.fr/WAN DeviceWAN Device20260105
...

In Practice

There are a few strange things about the way upnpc works. First, when you do a list, you’ll get an error at the end. Apparently, that’s normal. The program simply asks for entry zero, one, two… until it gets an error (a 713 error).

However, when I tried to add an open port to this particular router, it always failed, giving me an error that implied that the port was already in use. Of course, it wasn’t.

Through experimentation, I figured out that the UPnP service on the router (the one I can’t get into) isn’t running as root. So any port number less than 1,024 is unmappable in either direction. Of course, this may not be a problem for you if you have a sane router. You could argue whether this is a bug or not, but it certainly didn’t give a good error message.

Testing, One, Two…

Just to do a simple test, I issued the following command. (with my firewall off, just for testing):
upnpc -e HADTEST -a 192.168.1.133 8022 8023 tcp 3600
I verified the port opening using the -l option. Then I stood up a really dumb telnet-style server on the local port (8022):

socat readline TCP-LISTEN:8022,reuseaddr,fork

From a machine on another network, I issued a telnet command to my public IP (198.37.197.21):
telnet 198.37.197.21 8023
Of course, I could have used 8022 for both ports, but I wanted it to be clear which argument was which. At this point, typing some things on the remote machine should show right up on the local machine, punching through the firewall.

In case you forgot, you can escape out of Telnet using Control-] and then a “q” will close the program. You can also just terminate the socat program on the local side.

More Than One Way

It is a bummer I couldn’t open up an ssh port using this method, although you can run sshd on a high port and get there that way. But it is better than nothing. Better still would have been to replace the router, but that wasn’t an option in this case.

There are other tools out there if you are interested. NAT-PMP is easy to use from Python, for example. There’s also something called PCP (not the performance co-pilot, which is something else). Many routers don’t support either of these, and we hear that implementations are often buggy, just like UPnP.

For the record, NAT-PMP didn’t give me a better error message, either. So the moral is this: if you can, just punch a hole in your router the old-fashioned way. But if you can’t. Linux almost always gives you another option.

hackaday.com/2026/03/23/linux-…

A switch is simple: connect two pieces of metal together and bam! Except, it’s not that simple at high currents. How much current? Just about 400 car batteries worth would certainly cause some issues. This is the issue that [Technology Hobby] hoped to fix with his clever switch design.

While many content creators are great at finding or making high-current sources (looking at you, Styropyro), their switches can’t always hold up to the abuse. [Technology Hobby] found that many of the switches used by these creators had issues based on an inconsistent and limited contact area. Making a bigger contact patch is always fairly easy; keeping those contacts from skipping can be a bit more difficult.

[Technology Hobby] found success in making a V-shaped channel formed from separated contacts where a matching contact would bridge the gap between, completing the circuit. The construction of the high-current switch was simply done with a 3D printed frame filled with concrete for stiffness.

There’s a lot of fun with high current, but sometimes you need something more practical. For those needing some practical current supply, check out this retro-modern power supply!

youtube.com/embed/JeQpYYZf-d4?…

hackaday.com/2026/03/23/a-simp…

In the early days of aviation, pilots or their navigators used a plethora of tools to solve common navigation and piloting problems. There was definitely a need for some kind of computing aid that could replace slide rules, tables, and tedious dead-reckoning computations. This would become even more important during World War II, when there was a massive push to quickly train young men to be pilots.
The same, but different. A Pickett slide rule (top) and an E6B slide rule (bottom). (Own Work).
Today, we’d whip up some sort of computer device, but in the 1930s, computers weren’t anything you’d cram on a plane, even if they’d had any. For example, the Mark 1 Fire Control Computer during WW2 was 3,000 pounds of gears and motors.

The computer is made to answer flight questions like “how many pounds of fuel do I need for another hour of flying time?” or “How do I adjust my course if I have a particular crosswind?”

History

There were a rash of flight computers starting in the 1920s that were essentially specialized slide rules. The most popular one appeared in the late 1930s. Philip Dalton’s circular slide rule was cheap to produce and easy to use. As you’ll see, it is more than just an ordinary slide rule. Keep in mind, these were not computers in the sense we think of today. They were simple slide rules that easily did specialized math useful to pilots.

Dalton actually developed a number of computers. The popular Model B appeared in 1933, and there were refinements leading to additional models. The Mark VII was very popular. Even Fred Noonan, Amelia Earhart’s navigator, used a Mark VII.
A metal E6B (public domain).
Dalton thought the Mark VII was clunky and developed a way to do vector calculations using an endless belt inside the computer. This proved to expensive to make, so he created a flat wind computer and put, essentially, the Model B on the other side. While he called this the Model H, the Army called it the E6A.

In 1938, the Army Air Corps asked for a few minor changes and adopted the computer as the E6B, although pilots often call it the “whiz wheel” or the “Dalton Dead Reckoning Computer.” Oddly enough, some pilots still swear by the E6B, and flight schools sometimes make you learn them because they help you develop a feel for the math you don’t get with a calculator.

Sadly, Dalton died in a plane crash with a student pilot in 1941. P.V.H. Weems, a well-known navigator and Fred Noonan’s mentor, carried on the work of improving the E6B.

Besides, they are almost a perfect backup computer. Small, light, cheap, not prone to breaking, and they need no power. Some are made of cardboard, some of metal, and others of plastic. Wartime E6Bs were on a plastic that glowed under cockpit illumination. Later, there would be electronic or software E6Bs (see the video below), but a real whiz wheel is something you can hold in your hand, and you never have to change the battery.

youtube.com/embed/tAsOhbjDp7U?…

Not Just a Slide Rule

The front of the E6B is, essentially, a circular slide rule. What makes it unique, though, is that it has special scales and markings to deal with conversions of things like nautical miles or knots. Even the arrangement of the scales work to make a pilot’s life easier.

For example, the top of the wheel is a big mark that represents 60. Why? Because there are 60 minutes in an hour, and this makes it easy to compute things like pounds of fuel per hour.

It also lets you convert things like knots to nautical miles easily because the conversion factors are marked already.

If you know how to use a slide rule, you are almost immediately proficient on the front side of an E6B. Note that the sliding part of the computer is all about the wind computer (see below). All the calculation parts are just on the wheel, like a traditional circular slide rule.

The Back Side

The back side is a graphical vector solver for wind problems. You essentially use it to plot a wind triangle. You set the wind vector, the aircraft velocity vector, and you can read off the ground track. By moving things around, you can find your groundspeed, your wind correction angle, or your heading.On some E6Bs, you have to flip the slide to do low-speed or high-speed wind problems.

For an example wind problem, consider if you have wind at 200 degrees at 10 knots. Your true course is 150 degrees, and your true air speed is 130 knots. You would like to compute your ground speed, your true heading, and the wind correction angle.

One reason that the E6B remains useful for training is that it helps you develop intuition that is hard to get from a bunch of numbers on a calculator’s LEDs. You get a feel for how much wind will deflect your track 10 degrees, for example.

You can also use the E6B in reverse. If your groundspeed isn’t what you expect, you might set up the problem to put in your true parameters and solve for what the wind must be to make that result correct.

Sure, with GPS, you probably don’t need to figure out whether you have enough fuel to make it to another airport. But without GPS and a real computer, the E6B can do those things just fine.

Learning the E6B

If you actually want to learn how to use the E6B, we suggest watching a YouTube video. There are some short videos, and at least one that has 14 different videos. The good news is that the E6B hasn’t changed in many years, so any video you find should be just fine.

We like [Aviation Theory’s] two videos, which are worth watching (see part 1, below).

youtube.com/embed/FxkM-z-6b5k?…

If you want to follow along and don’t have an E6B, you can try one virtually in your browser. Or, pick one up. The cardboard ones are fairly inexpensive and widely available.

The Legacy of the E6B

While the E6B isn’t the essential kit it once was, it is still a valuable aid for pilots. It is also a great example of how to turn an ordinary slide rule into something specialized.

We have a feeling Gene Roddenberry, an avid pilot, was very familiar with the E6B. He even thought they’d still use them in the 23rd century, as you can see in the video clip below.

youtube.com/embed/V1nKBrkPUeA?…

You can also catch a glimpse of these in old US Army Air Corps films like the one below (about the 14-minute mark), although we couldn’t find any training specifically for the E6-B that survived.

youtube.com/embed/tEjJIhDanEY?…

If you like old analog computers, read [Nicola Marras’] book. Maybe Spock would have preferred a Star Trekulator.

[Featured image: “E6b-slide-rule” by [Duke]

hackaday.com/2026/03/23/the-ze…