The function generator circuit on a breadboard

555-Based Square-Wave And Triangle-Wave Function Generator Build For Beginners

February 7, 2026 by John Elliot V 3 Comments

Over on YouTube [Andrew Neal] has a Function Generator Build for Beginners.

As beginner videos go this one is fairly comprehensive. [Andrew] shows us how to build a square-wave generator on a breadboard using a 555 timer, explaining how its internal flip-flop is controlled by added resistance and capacitance to become a relaxation oscillator. He shows how to couple a potentiometer to vary the frequency.

He then adds an integrator built from a TL082 dual op amp to convert the circuit to a triangle-wave generator, using its second op amp to build a binary inverter. He notes that a binary inverter is usually implemented with a comparator, but he uses the op amp because it was spare and could be put to good use. Again, potentiometers are added for frequency control, in this case a 1 MΩ pot for coarse control and a 10 kΩ pot for fine control. He ends with a challenge to the viewer: how can this circuit be modified to be a sine-wave generator? Sound off in the comments if you have some ideas!

If you’re interested to know more about function generators check out A Function Generator From The Past and Budget Brilliance: DHO800 Function Generator.

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A graph of current versus time for circuits with and without inductors

A Deep Dive Into Inductors

February 5, 2026 by John Elliot V 3 Comments

[Prof MAD] runs us through The Hidden Power of Inductors — Why Coils Resist Change.

The less often used of the passive components, the humble and mysterious inductor is the subject of this video. The essence of inductance is a conductor’s tendency to resist changes in current. When the current is steady it is invisible, but when current changes an inductor pushes back. The good old waterwheel analogy is given to explain what an inductor’s effect is like.

There are three things to notice about the effect of an inductor: increases in current are delayed, decreases in current are delayed, and when there is no change in current there is no noticeable effect. The inductor doesn’t resist current flow, but it does resist changes in current flow. This resistive effect only occurs when current is changing, and it is known as “inductive reactance”.

After explaining an inductor’s behavior the video digs into how a typical inductor coil actually achieves this. The basic idea is that the inductor stores energy in a magnetic field, and it takes some time to charge up or discharge this field, accounting for the delay in current that is seen.

There’s a warning about high voltages which can be seen when power to an inductor is suddenly cut off. Typically a circuit will include snubber circuits or flyback diodes to help manage such effects which can otherwise damage components or lead to electric shock.

[Prof MAD] spends the rest of the video with some math that explains how voltage across an inductor is proportional to the rate of change of current over time (the first derivative of current against time). The inductance can then be defined as a constant of proportionality (L). This is the voltage that appears across a coil when current changes by 1 ampere per second, opposing the change. The unit is the volt-second-per-ampere (VsA^-1) which is known as the Henry, named in honor of the American physicist Joseph Henry.

Inductance can sometimes be put to good use in circuits, but just as often it is unwanted parasitic induction whose effects need to be mitigated, for more info see: Inductance In PCB Layout: The Good, The Bad, And The Fugly.

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[Yang-Hui He] Presents To The Royal Institution About AI And Mathematics

February 2, 2026 by John Elliot V 2 Comments

Over on YouTube you can see [Yang-Hui He] present to The Royal Institution about Mathematics: The rise of the machines.

In this one hour presentation [Yang-Hui He] explains how AI is driving progress in pure mathematics. He says that right now AI is poised to change the very nature of how mathematics is done. He is part of a community of hundreds of mathematicians pursuing the use of AI for research purposes.

[Yang-Hui He] traces the genesis of the term “artificial intelligence” to a research proposal from J. McCarthy, M.L. Minsky, N. Rochester, and C.E. Shannon dated August 31, 1955. He says that his mantra has become: connectivism leads to emergence, and goes on to explain what he means by that, then follows with universal approximation theorems.

He goes on to enumerate some of the key moments in AI: Descartes’s bête-machine, 1617; Lovelace’s speculation, 1842; Turing test, 1949; Dartmouth conference, 1956; Rosenblatt’s Perceptron, 1957; Hopfield’s network, 1982; Hinton’s Boltzmann machine, 1984; IBM’s Deep Blue, 1997; and DeepMind’s AlphaGo, 2012.

He continues with some navel-gazing about what is mathematics, and what is artificial intelligence. He considers how we do mathematics as bottom-up, top-down, or meta-mathematics. He mentions about one of his earliest papers on the subject Machine-learning the string landscape (PDF) and his books The Calabi–Yau Landscape: From Geometry, to Physics, to Machine Learning and Machine Learning in Pure Mathematics and Theoretical Physics.

He goes on to explain about Mathlib and the Xena Project. He discusses Machine-Assisted Proof by Terence Tao (PDF) and goes on to talk more about the history of mathematics and particularly experimental mathematics. All in all a very interesting talk, if you can find a spare hour!

In conclusion: Has AI solved any major open conjecture? No. Is AI beginning to help to advance mathematical discovery? Yes. Has AI changed the speaker’s day-to-day research routine? Yes and no.

If you’re interested in more fun math articles be sure to check out Digital Paint Mixing Has Been Greatly Improved With 1930s Math and Painted Over But Not Forgotten: Restoring Lost Paintings With Radiation And Mathematics.

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Lumafield battery quality report cover page

Lumafield Peers Into The 18650 Battery

January 31, 2026 by John Elliot V 22 Comments

[Alex Hao] and [Andreas Bastian] of Lumafield recently visited with [Adam Savage] to document their findings after performing X-ray computed tomography scans on over 1,000 18650 lithium-ion batteries.

The short version — don’t buy cheap cells! The cheaper brands were found to have higher levels of manufacturing defects which can lead them to being unsafe. All the nitty-gritty details are available in the report, which can be downloaded for free from Lumafield, as well as the Tested video they did with [Adam] below.

Actually we’ve been talking here at Hackaday over at our virtual water-cooler (okay, okay, our Discord server) about how to store lithium-ion batteries and we learned about this cool bit of kit: the BAT-SAFE. Maybe check that out if you’re stickler for safety like us! (Thanks Maya Posch!)

We have of course heard from [Adam Savage] before, check out [Adam Savage] Giving A Speech About The Maker Movement and [Adam Savage]’s First Order Of Retrievability Tool Boxes.

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Surviving The RAM Price Squeeze With Linux In-Kernel Memory Compression

January 31, 2026 by John Elliot V 42 Comments

You’ve probably heard — we’re currently experiencing very high RAM prices due mostly to increased demand from AI data centers.

If you’ve been priced out of new RAM you are going to want to get as much value out of the RAM you already have as possible, and that’s where today’s hack comes in: if you’re on a Debian system read about ZRam for how to install and configure zram-tools to enable and manage the Linux kernel facilities that enable compressed RAM by integrating with the swap-enabled virtual memory system. We’ve seen it done with the Raspberry Pi, and the concept is the same.

Ubuntu users should check out systemd-zram-generator instead, and be aware that zram might already be installed and configured by default on your Ubuntu Desktop system.

If you’re interested in the history of in-kernel memory compression LWN.net has an old article covering the technology as it was gestating back in 2013: In-kernel Memory Compression. For those trying to get a grip on what has happened with RAM prices in recent history, a good place to track memory prices is memory.net and if you swing by you can see that a lot of RAM has gone up as much as four times in the last three or four months.

If you have any tips or hacks for memory compression on other platforms we would love to hear from you in the comments section!

A man cutting wood with a circular bench saw

Ultimate Picture Frame Combines Walnut And 3D Printing

January 28, 2026 by John Elliot V 8 Comments

[Make Something] boasts he has made probably the fanciest picture frame you’ll ever see. He started with an original sign purchased on eBay and then made it to be bigger, brighter, and better. The frame is of solid walnut with back-lighting for the imagery all chasing that classic mid-century modern style. The backlit photo was taken the “hard way”, with an actual film camera and a road-trip to the picturesque site at Yellowstone. [Make Something] then developed the film himself in his home studio.

For the chimney [Make Something] used a new trick he learned in Autodesk Fusion: you take a photo of an object, convert to black and white, and then use the light/dark values to emboss or deboss a surface. To do this he took photos of the brick wall outside his shop and used that as the basis of the textured chimney he made with his 3D printer.

If you’re interested in other projects made from solid walnut, check out 3D Printed Spirograph Makes Art Out Of Walnut and Walnut Case Sets This Custom Arduino-Powered RPN Calculator Apart From The Crowd.

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[nanofix] and his assortment of tweezers

Reviewing Tweezers For Microsoldering And SMD Work

January 24, 2026 by John Elliot V 9 Comments

Attributed to Picasso was the notion that when art critics get together they talk about content, style, trend, and meaning; but that when painters get together they talk about where to get the best turpentine. We can extend that sentiment into the digital age by saying that when philosophers get together they talk about ideas, theory, and meaning; but when hackers get together they talk about where to get the best tweezers.

In this video [nanofix] runs us through his collection of tweezers talking about what he likes and doesn’t like for each. If you’re just getting into microsoldering this video will have some tips about where you should start, and if you’ve been soldering tiny stuff for a while you might find some ideas for a helpful new bit of kit, or two.

If you’re interested in tweezers and novel applications you might want to check out “smart” tweezers, which can read capacitance and resistance values on the fly. Or read about a suction based SMD tool, which can securely hold SMD components with less risk of them flying across the bench and disappearing forever into the carpet on the floor.

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