Photo of AlphaPhoenix looking at an airplane flying through the air

Weighing An Airplane As It Flies Overhead

June 18, 2025 by John Elliot V 19 Comments

Recently, [AlphaPhoenix] weighed an airplane. Normally, that wouldn’t be much of an accomplishment. Except in this case, the airplane happened to be in flight at the time. In fact we’re not sure what is more remarkable, as he not only weighed real actual airplanes but a paper airplane too!

The sealed box essentially acts as a pressure sensor.

To test the concept, a large scale is made from foamcore and four load cells which feed into an Arduino which in turn is connected to a laptop for a visualization. After a brief test with a toy car, [AlphaPhoenix] goes on to weigh a paper airplane as it flies over the scale. What we learn from the demonstration is that any weight from a flying object is eventually transferred to the ground via the air.

In the second part of the video a new, smaller, type of scale is created and taken to the airport where airplanes flying overhead are weighed over the course of three days. This new apparatus is basically a pressure sensor enclosed in a nominally air-tight box, essentially a fancy type of barometer. Measurements are taken, assumptions are made, and figures are arrived at. Unfortunately the calculated results are off by more than one order of magnitude, but that doesn’t stop this experiment from having been very cool!

If you’re interested in weighing things for fun or profit be sure to check out Hackaday Prize 2022: Arduino-Powered Weighing Scale Has A Real Analog Display or Reverse Engineering A Bathroom Scale For Automated Weight Tracking.

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Making A Brushless DC Motor Winding Machine

June 17, 2025 by John Elliot V 28 Comments

Over on his YouTube channel our hacker [Yuchi] is building an STM32 BLDC motor winding machine.

This machine is for winding brushless motors because manual winding is highly labor intensive. The machine in turn is made from four brushless motors. He is using the SimpleFOC library to implement closed-loop angle control. Closed-loop torque control is also used to maintain correct wire tension.

The system is controlled by an STM32G431 microcontroller. The motor driver used is the DRV8313. There are three GBM5208 75T Gimbal motors for close-loop angle control, and one BE4108 60T Gimbal motor for torque control. The torque control motor was built with this machine! [Yuchi] says that the Gimbal motors used are designed to be smooth, precise, and powerful at low speeds.

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A DIY Version Of The Franck-Hertz Experiment

June 17, 2025 by John Elliot V 5 Comments

The Franck–Hertz experiment was a pioneering physics observation announced in 1914 which explained that energy came in “packets” which we call “quanta”, marking the beginning of quantum physics. Recently, [Markus Bindhammer] wrote in to let us know he had redone the experiment for himself.

In the original experiment a mercury vacuum tube was used, but in his recreation of the experiment [Markus] uses a cheaper argon tube. He still gets the result he is looking for though, which is quite remarkable. If you watch the video you will see the current readings clump around specific voltage levels. These voltage levels indicate that energy is quantized, which was a revolutionary idea at the time. If you’re interested in how contemporary physics regards, particles, waves, and quanta, check out this excellent presentation: But What Actually Is a Particle? How Quantum Fields Shape Reality.

Before closing we have to say that the quality of [Markus]’s build was exceptional. He made a permanent enclosure for his power supplies, made custom PCBs, used ferrule crimps for all his wire interconnects, included multiple power switches and dials, professionally labeled and insulated everything, and even went to the trouble of painting the box! Truly a first class build. One thing that surprised us though was his use of rivets where we would almost certainly have used bolts or screws… talk about confidence in your workmanship!

If you’re interested in quantum physics it is certainly a topic we have covered here at Hackaday. Check out Quantum Mechanics And Negative Time With Photon-Atom Interactions or Shedding Light On Quantum Measurement With Calcite.

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Expanding Racks In The Spirit Of The Hoberman Sphere

June 16, 2025 by John Elliot V 7 Comments

If you’re a mechanical engineering wonk, you might appreciate this latest video from [Henry Segerman] wherein he demonstrates his various expanding racks.

[Henry] explains how the basic “double-rack” unit can be combined to make more complex structures. These structures are similar in spirit to the Hoberman sphere, which is a compact structure that can be expanded to fill a large space.

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Adapting An Old Rotary Dial For Digital Applications

June 13, 2025 by John Elliot V 26 Comments

Today in old school nostalgia our tipster [Clint Jay] wrote in to let us know about this rotary dial.

If you’re a young whippersnapper you might never have seen a rotary dial. These things were commonly used on telephones back in the day, and they were notoriously slow to use. The way they work is that they generate a number of pulses corresponding to the number you want to dial in. One pulse for 1, two pulses for 2, and so on, up to nine pulses for 9, then ten pulses for 0.

We see circuits like this here at Hackaday from time to time. In fact, commonly we see them implemented as USB keyboards, such as in Rotary Dial Becomes USB Keyboard and Rotary Dialer Becomes Numeric Keypad.

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Build A 400 MHz Logic Analyzer For $35

June 12, 2025 by John Elliot V 14 Comments

What do you do when you’re a starving student and you need a 400 MHz logic analyzer for your digital circuit investigations? As [nanofix] shows in a recent video, you find one that’s available as an open hardware project and build it yourself.

The project, aptly named LogicAnalyzer was developed by [Dr. Gusman] a few years back, and has actually graced these pages in the past. In the video below, [nanofix] concentrates on the mechanics of actually putting the board together with a focus on soldering. The back of the build is the Raspberry Pi Pico 2 and the TXU0104 level shifters.

If you’d like to follow along at home, all the build instructions and design files are available on GitHub. For your convenience the Gerber files have been shared at PCBWay

Of course we have heaps of material here at Hackaday covering logic analyzers. If you’re interested in budget options check out $13 Scope And Logic Analyzer Hits 18 Msps or how to build one using a ZX Spectrum! If you’re just getting started with logic analyzers (or if you’re not sure why you should) check out Logic Analyzers: Tapping Into Raspberry Pi Secrets.

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Back To The Future Lunchbox Cyberdeck

June 10, 2025 by John Elliot V 4 Comments

Our hacker [Valve Child] wrote in to let us know about his Back to the Future lunchbox cyberdeck.

Great Scott! This is so awesome. We’re not sure what we should say, or where we should begin. A lot of you wouldn’t have been there, on July 3rd, 1985, nearly forty years ago. But we were there. Oh yes, we were there. On that day the movie Back to the Future was released, along with the hit song from its soundtrack: Huey Lewis & The News – The Power Of Love.

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