Foil Leyden Jar Helps Bring Crookes Tube To Life

May 23, 2025 by Seth Mabbott 7 Comments

It might be too soon to consider the innards of the old CRT monitor at the back of your closet to be something worth putting on display in your home or workshop. For that curio cabinet-worthy appeal, you need to look a bit further back. Say, about 150 years. Yes, that’ll do. A Crookes tube, the original electron beam-forming vacuum tube of glass, invented by Sir William Crookes et al. in the late 19th century, is what you need.

And a Crookes tube is what [Markus Bindhammer] found on AliExpress one day. He felt that piece of historic lab equipment was asking to be put on display in proper fashion. So he set to work crafting a wooden stand for it out of a repurposed candlestick, a nice piece of scrap oak, and some brass feet giving it that antique mad-scientist feel.

After connecting a high voltage generator and switch, the Crookes tube should have been all set, but nothing happened when it was powered up. It turned out that a capacitance issue was preventing the tube from springing to life. Wrapping the cathode end of the tube in aluminum foil, [Markus] formed what is effectively a Leyden jar, and that was the trick that kicked things into action.

As of this writing, there are no longer any Crookes tubes that we could find on AliExpress, so you’ll have to look elsewhere if you’re interested in showing off your own 19th century electron-streaming experiment. Check out the Crookes Radiometer for some more of Sir Williams Crookes’s science inside blown glass.

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Tablet Suspension System Avoids Fatigue At Bedtime

May 3, 2025 by Seth Mabbott 12 Comments

You know how it is. You’re all cozy in bed but not quite ready to doze off. You’re reading Hackaday (Hackaday is your go-to bedtime reading material, right?) or you’re binge-watching your latest reality TV obsession on your tablet. You feel the tablet growing heavier and heavier as your arms fatigue from holding it inches above your face. You consider the embarrassment you’ll endure from explaining how you injured your nose as the danger of dropping the tablet gradually increases. The struggle is real.

[Will Dana] has been engineering his way out of this predicament for a few years now, and with the recent upgrade to his iPad suspension system he is maximizing his laziness, but not without putting in a fair amount of hard work first.

The first iteration of the device worked on a manual pulley system whereby an iPad was suspended from the ceiling over his bed on three cords. Pulling on a cord beside the bed would raise the bracket used for holding the iPad out of the way while not in use. This new iteration takes that pesky cord pulling out of the user’s hands, replacing it with a motorized winch. A spot of dark ink on one of the cords in combination with a light sensor helps to calibrate the system so that the ESP32 which controls it always knows the proper limits of operation.

Of course, if, like [Will], you’re using an ESP32, and your room is already fully controlled by a voice interface, you may as well integrate the two. After all, there is no sense in wasting precious energy by pressing buttons. Utter a simple command to Alexa once you’re tucked in, and it’s time for hands-free entertainment.

We’ve covered several of [Will]’s previous creations, such as his Motorized Relay Computer and Harry Potter-inspired Sorting Hat.

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Revivification: a Room with cymbals and plinth

Posthumous Composition Being Performed By The Composer

April 25, 2025 by Seth Mabbott 15 Comments

Alvin Lucier was an American experimental composer whose compositions were arguably as much science experiments as they were music. The piece he is best known for, I Am Sitting in a Room, explored the acoustics of a room and what happens when you amplify the characteristics that are imparted on sound in that space by repeatedly recording and playing back the sound from one tape machine to another. Other works have employed galvanic skin response sensors, electromagnetically activated piano strings and other components that are not conventionally used in music composition.

Undoubtedly the most unconventional thing he’s done (so far) is to perform in an exhibit at The Art Gallery of Western Australia in Perth which opened earlier this month. That in itself would not be so unconventional if it weren’t for the fact that he passed away in 2021. Let us explain.

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Hydroplaning RC Jet Boat Steers Clear Of Convention

April 19, 2025 by Seth Mabbott 19 Comments

[CovaConcepts], who has a background in motorsports, has been busy designing an unconventional radio-controlled watercraft she calls the HydraJet.

There are two key design decisions that make the HydraJet what it is. First, she chose to propel the boat by pushing against the air via an electric ducted fan (EDF) rather than the water via a traditional water propeller. This simplified construction and made it more affordable, partly because she already had the fan on hand.

Her other design choice was to use wings underneath the boat to lift it out of the water. Not as hydrofoils, where the wings ride below the surface of the water, but for hydroplaning where the wings ride on the surface of the water. Lifting the vehicle out of the water, of course, reduces drag, improving performance as we’ve often seen with high speed watercraft (including RC models) as well as slower bicycle-powered ones. The choice to rely on hydroplaning also reduces the complexity of the design. Certain hydrofoil designs need to make adjustments in order to keep the vehicle at a steady level, whereas a hydroplaning wings can use a static angle. Hydrofoils also must overcome challenges to maintain stability.

[CovaConcepts] hopes to eventually scale the HydraJet up large enough to carry human passengers and we’re looking forward to the opportunity to take it for a spin around the lake.

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This Potato Virtual Assistant Is Fully Baked

April 15, 2025 by Seth Mabbott 10 Comments

There are a number of reasons you might want to build your own smart speaker virtual assistant. Usually, getting your weather forecast from a snarky, malicious AI potato isn’t one of them, unless you’re a huge Portal fan like [Binh Pham].

[Binh Pham] built the potato incarnation of GLaDOS from the Portal 2 video game with the help of a ReSpeaker Light kit, an ESP32-based board designed for speech recognition and voice control, and as an interface for home assistant running on a Raspberry Pi.

He resisted the temptation to use a real potato as an enclosure and wisely opted instead to print one from a 3D file he found on Thingiverse of the original GLaDOS potato. Providing the assistant with the iconic synthetic voice of GLaDOS was a matter of repackaging an existing voice model for use with Home Assistant.

Of course all of this attention to detail would be for naught if you had to refer to the assistant as “Google” or “Alexa” to get its attention. A bit of custom modelling and on-device wake word detection, and the cyborg tuber was ready to switch lights on and off with it’s signature sinister wit.

We’ve seen a number of projects that brought Portal objects to life for fans of the franchise to enjoy, even an assistant based on another version of the GLaDOS the character. This one adds a dimension of absurdity to the collection.

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