Vista Normal

Hay nuevos artículos disponibles. Pincha para refrescar la página.
AnteayerSalida Principal

Foil Leyden Jar Helps Bring Crookes Tube to Life

23 Mayo 2025 at 08:00
Crookes Tube

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.

Tablet Suspension System Avoids Fatigue at Bedtime

3 Mayo 2025 at 20:00

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.

Posthumous Composition Being Performed by the Composer

25 Abril 2025 at 11:00
Revivification: a Room with cymbals and plinth

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.

While he was still alive, Lucier entered into a collaboration with a team of artists and biologists to create an exhibit that would push art, science and our notions of what it means to live beyond one’s death into new ground.

The resulting exhibit, titled Revivication, is a room filled with gong-like cymbals being played via actuators by Lucier’s brain…sort of. It is a brain organoid, a bundle of neurons derived from a sample of his blood which had been induced into pluripotent stem cells. The organoid sits on a mesh of electrodes, providing an interface for triggering the cymbals.

Brain Organoid on a mesh of electrodes.
A brain organoid derived from Alvin Lucier’s blood cells sits on a mesh of electrodes.

“But the organoid isn’t aware of what’s happening, it’s not performing” we hear you say. While it is true that the bundle of neurons isn’t likely to have intuited hundreds of years of music theory or its subversion by experimental methodology, it is part of a feedback loop that potentially allows it to “perceive” in some way the result of its “actions”.

Microphones mounted at each cymbal feed electrical stimulus back to the organoid, presumably providing it with something to respond to. Whether it does so in any meaningful way is hard to say.

The exhibit asks us to think about where creativity comes from. Is it innate? Is it “in our blood” so to speak? Do we have agency or are we being conducted? Can we live on beyond our own deaths through some creative act? What, if anything, do brain organoids experience?

This makes us think about some of the interesting mind-controlled musical interfaces we’ve seen, the promise of pluripotent stem cell research, and of course those brain computer interfaces. Oh, and there was that time the Hackaday Podcast featured Alvin Lucier’s I Am Sitting in a Room on What’s that Sound.

❌
❌