This One Simple Trick Rehabilitates Scratchy Sounding Speakers

We’ve all picked up a radio and switched it on, only to hear an awful scratchy noise emitting from the speaker. [Richard Langer] is no stranger to this problem, and has identified a cheap and unusual solution—using toilet paper!

The cause of the scratchy sound is that when the speaker’s paper cone warps, it can cause the voice coil to rub up against the magnet assembly. In time, this wears out insulation on the coil’s turns, damaging the speaker. [Richard] found that realigning the coil to its proper place would rectify the issue. This can be achieved by stuffing a small amount of toilet paper in the back of the speaker, between the cone and the metal housing.

To identify the right spot to put the paper, one simply presses on the back of the speaker with a pen while listening out for the scratchy sound to stop. The paper can then be stuffed into this area to complete the fix. This can realign the cone and voice coil and stop the scratchy sound for good.

[Richard] notes that this method can be quite long-lasting in some cases. Failing that, it should serve long enough for you to order a replacement speaker. Video after the break.

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MRI Resolution Progresses From Millimeters To Microns

Neuroscientists have been mapping and recreating the nervous systems and brains of various animals since the microscope was invented, and have even been able to map out entire brain structures thanks to other imaging techniques with perhaps the most famous example being the 302-neuron brain of a roundworm. Studies like these advanced neuroscience considerably but even better imaging technology is needed to study more advanced neural structures like those found in a mouse or human, and this advanced MRI machine may be just the thing to help gain better understandings of these structures.

A research team led by Duke University developed this new MRI technology using an incredibly powerful 9.4 Tesla magnet and specialized gradient coils, leading to an image resolution an impressive six orders of magnitude higher than a typical MRI. The voxels in the image measure at only 5 microns compared to the millimeter-level resolution available on modern MRI machines, which can reveal microscopic details within brain tissues that were previously unattainable. This breakthrough in MRI resolution has the potential to significantly advance understanding of the neural networks found in humans by first studying neural structures in mice at this unprecedented detail.

The researchers are hopeful that this higher-powered MRI microscope will lead to new insights and translate directly into advancements healthcare, and presuming that it can be replicated, used on humans safely, and becomes affordable, we would expect it to find its way into medical centers as soon as possible. Not only that, but research into neuroscience has plenty of applications outside of healthcare too, like the aforementioned 302-neuron brain of the Caenorhabditis elegans roundworm which has been put to work in various robotics platforms to great effect.

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Mystery 1802 Computer Was A Homebrew Project

[CelGenStudios] has an impressive collection of vintage hardware. One that really struck us came from a thrift store in Canada, so the original provenance of it is unknown. It looks like someone’s handmade interpretation of a SOL-20. There’s a wooden and sheet metal box containing a keyboard looted from an old dedicated word processor (back when a word processor was a machine, not a piece of software). Inside? Some vintage-looking hand-drawn PC boards, including a backplane with two boards. One contains an RCA 1802 and a little bit of memory. There’s also a video card with more memory on it than the CPU.

We loved the 1802, and we disagree with [CelGenStudios] that it “wasn’t that popular.” It was super popular in some areas. The CMOS processor was popular in spacecraft and among homebrew builders. There were a few reasons for that. Unlike some early CPUs, you didn’t need much to bootstrap a system. It would run on 5V and had a “DMA” mode to key data in with just a few simple switches and buttons. You didn’t need a ROM-based monitor to get the system to work. In addition, the design could be low power, and the static design meant you could slow or stop the clock for very low power compared to many other systems of the day.

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Making Neon Trees The Easy Way With No Oven Pumps Required

Neon lamps are fun and beautiful things. Hackers do love anything that glows, after all. But producing them can be difficult, requiring specialized equipment like ovens and bombarders to fill them up with plasma. However, [kcakarevska] has found a way to make neon lamps while bypassing these difficulties.

[kcakarevska] used the technique to great effect on some neon tree sculptures.
The trick is using magnesium ribbon, which is readily available form a variety of suppliers. The ribbon is cut into small inch-long fragments and pushed into a borosilicate tube of a neon sculpture near the electrode. Vacuum is then pulled on the tube down to approximately 5 microns of pressure. The tube is then closed off and the electrode is heated using an automotive-type induction heater. In due time, this vaporizes the magnesium which then creates a reactive getter coating on the inside of the tube. This picks up any oxygen, water vapor, or other contaminants that may have been left inside the tube without the need for an oven vacuum pumping stage. The tube is then ready to be filled with neon. After about 24 to 48 hours of running, the getter coating will have picked up the contaminants and the tube will glow well.

It’s a useful technique, particularly for complex neon sculptures that won’t readily fit in an oven for pumpdown. If the glasswork is still too daunting, though, you can always use other techniques to get a similar look. Video after the break.

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A Temperature-Sensing Magnetic Stir Bar

Magnetic stirring bars are the coolest piece of equipment you’ll see in a high-school chemistry lab. They’re a great way for agitating a solution without having to stand there manually and do it yourself. [Applied Science] has now made a magnetic stir bar that features an integrated temperature sensor.

The device is essentially an RFID temperature sensor snuck inside a custom-made magnetic stir bar. The bar is paired with a smart hotplate base that displays the temperature readings. As a bonus, it can detect when the magnetic stir bar is out of place or not in sync, prompting it to slow down the spin motor until the stir bar is turning properly again.

The video also notes that the stir bar could be instrumented for even greater functionality. A Hall effect sensor could measure the magnetic slip angle of the stir bar, and provide useful readings of liquid viscosity. Alternatively, a pressure sensor in the stir bar could potentially measure liquid level based on hydrostatic pressure.

It’s a great quality-of-life improvement for regular lab work. It eliminates the need for bulky temperature probes that often get in the way. We’ve featured some interesting temperature sensors before, too.

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VCF East 2023: Andy Geppert Talks Core Memory

Do you know core memory? Our prehistoric predecessors would store data in the magnetic fields of ferrite rings, reading out the ones and zeroes by setting the magnetic field and detecting if a small current is induced in a sense wire, indicating that the bit flipped, or not detecting the current, in which case it didn’t. Core memory is non-volatile, rad hard, and involved a tremendous amount of wire weaving to fabricate. And it’s pretty cool.

[Andy Geppert] wants to get you hands-on with this anachronistic memory, and builds kits to demo how it works. [Tom Nardi] and [Bil Herd] caught up with him at the Vintage Computer Festival East last weekend, and got him to demo his Core64 project for them. (Video, embedded below.)

The design of Core64 displays its state in lights at all times. And this means that you can write to it using either the onboard Pi Pico, for a blinky light show, or with a magnetic stylus, setting each bit’s magnetic state by hand. This turns it into a magnetic memory tablet and is a sweet demonstration of the principles that make it all work. Or, if you pulse the lines at just the right frequency, you can make the cores spin!

Watch [Andy] explaining it in our interview here, and stay tuned for more coming from VCF East 2023 soon.

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Ask Hackaday: Split Rail Op Amp Power Supply

Water cooler talk at the office usually centers around movies, sports, or life events. Not at Hackaday. We have the oddest conversations and, this week, we are asking for your help. It is no secret that we have a special badge each year for Supercon. Have you ever wondered where those badges come from? Sometimes we do too. We can’t tell you what the badge is going to be for Supercon 2023, but here’s a chance for you to contribute to its design.

What I can tell you is that at least part of the badge is analog. Part, too, is digital. So we were discussing a seemingly simple question: How do we best generate a bipolar power source for the op amps on a badge? Like all design requests, this one is unreasonable. We want:

  • Ideally, we’d like a circuit to give us +/- 9 V to +/- 12 V at moderately low current, say in the tens of milliamps. Actual values TBD.
  • Low noise: analog circuitry, remember?
  • Lightweight: it is going on a badge
  • Battery operated: the badge thing again
  • Cheap: we only have a couple bucks in the budget for power
  • Available in quantity: we’ll need ~600 of these

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