Computing Via (Virtual) Dominos

April 18, 2024 by 4 Comments

Back in 2012, [Matt Parker] and a team built a computer out of dominos for the Manchester Science Festival. [Andrew Taylor], part of the team that built the original,  has built a series of virtual domino puzzles to help explain how the computer worked. He also links to a video from the event, but be warned: the video contains some spoilers for the puzzles. If you are ready for spoilers, you can watch the video below.

The original computer could add two three-bit numbers and provide a four-bit result. We don’t want to give away the answers, but the inverter is quite strange. If you don’t want to puzzle it out, you can press the “reveal answer” to see [Andrew’s] solutions. Press “play” and watch the dominos fall.

Continue reading “Computing Via (Virtual) Dominos” →

Remove Wall Plugs Fast With A Custom Tool

April 18, 2024 by 25 Comments

The best thing about buying your own home is that you can hang things on the walls. It’s a human right all too often denied to renters the world over. Regardless, five years later, when you’re doing the mandatory minimalist remodel, you’ll be ruing the day you put in all those wall anchors. At that point, consider removing them with this nifty tool from [XDIY with Itzik].

The design aims to remove wall anchors as cleanly as possible. It’s easiest to watch the video to get the idea of how it works.

The tool features a block which holds a bearing. That bearing acts as a rotating stop for a wood screw. The idea is that you place the block against the wall, and use a power drill to drive a wood screw into the anchor at high speed. The screw can’t move forward, so the threads basically yank the plug out of the wall, and relatively neatly at that. Once removed, there’s a little push stopper you can use to hold the old plug in place as you remove the wood screw from the device, ready to go again.

[Itzik] demonstrates the device by removing ten wall plugs in just 40 seconds. If you’ve got a lot to do, or it’s a job you do regularly, you might like to have this tool in your kit.

Oftentimes, having the right tool can make a job ten times faster, and this seems like one of those cases. Video after the break.

Continue reading “Remove Wall Plugs Fast With A Custom Tool” →

DIY Quad-Motor Go-Kart Is A Thrilling Ride

April 18, 2024 by 18 Comments

[Peter Holderith] set out some time ago to build an electric go-kart. That by itself is not terribly unusual, but where his project diverts from the usual is in the fact that each of the four wheels has an integrated hub motor.

It might not look it, but each wheel has an integrated hub motor.

This kart project is a bit of a work in progress, with [Peter] previously building (then scrapping) a failed attempt at a cheap suspension system. But it’s completely operational with all four wheels able to deliver a monstrous amount of power despite being limited by the power supply (a battery pack salvaged from an Audi Q5 Hybrid).

The kart might not look it, but it weighs 177 pounds (80 kg) with the battery and motors accounting for nearly half of that. What is is like to drive? “Nothing short of thrilling,” says [Peter]. It’s got no suspension and is pretty bare bones, not to mention limited in power by the battery, but [Peter] finds it a satisfying drive that nevertheless delivers car-like cues in the driving experience. The build isn’t done, and [Peter] plans to see if more power is available by switching battery chemistries rather than add more battery weight.

Building and driving electric vehicles can be remarkably satisfying, and it’s an area in which hobbyists can meaningfully innovate. Self-balancing one-wheeled vehicles for example look like a ton of fun. Heck, researchers have discovered that even rats seem to enjoy driving just for the fun of it.

Early CD Player Teardown

April 18, 2024 by 13 Comments

While CD players are nothing new today, they were the height of high-tech in the early 1980s. [w1ngsfly] shows us the inside of a Phase Linear 9500 player from 1983. Not only does it have many components, but it is also mechanically unusual.

The CD loads into a toaster-like slot and even pops out like a piece of toast. The tracking mechanism is quite complex, and there’s something that looks suspiciously like a dial string from an old slide rule tuner radio. Apparently, the unit was made by Kyocera and is internally similar to a Kyocera DA-01.

There’s a “head position” indicator that is actually just an LED connected to the tracking mechanism. The front panel controls look great but also allow you to control the head position exactly. As [w1ngsfly] mentions, it is almost like moving a turntable’s tonearm where you can drop it anywhere you want.

If we recall, they were about $600 to $1,000 new. If Phase Linear doesn’t ring a bell, they were well known in their day. Founded by [Bob Carver] and [Steve Johnston], the company was bought by Pioneer before the introduction and, later, by Jensen before the introduction of the 9500. [Bob] would go on to found Carver Corporation. You can find plenty of history about the company online.

We’ve seen CD players that look older. These days, CD drives are cheap and they are easy enough to control.

Continue reading “Early CD Player Teardown” →

IKEA BEKANT sit/stand desk with a new controller attached

LYFT: Standing Up For Better IKEA BEKANT Control

April 18, 2024 by 5 Comments

The IKEA BEKANT sit/stand desk is kind of a lifesaver — even if you don’t personally go between sit and stand much, the adjustability makes sharing the desk a breeze. Sharing was the case in [Matthias]’ house during the pandemic, as he and his wife took turns using the desk. Switching between their two preferred heights quickly became annoying, so [Matthias] engineered LYFT, a replacement controller that stores up to four settings.

In addition, the new SAMD21-based controller allows them to raise and lower the desk without having to hold the button down. And finally, having a digital readout showing the position is just plain cool. As you’ll see in the manual (PDF), LYFT is as easy to set up and use as the average flat-packed product.

In order to make this work, [Matthias] had to figure out how the desk’s motors communicate out of the box, and he did so with the help of a BEKANT controller project by [Greg Cormier]. You won’t find LYFT at the blue and yellow, at least not yet; for now, you’ll have to shop Tindie or build it yourself.

A standard-compliant MXM card installed into a laptop, without heatsink

MXM: Powerful, Misused, Hackable

April 18, 2024 by 17 Comments

Today, we’ll look into yet another standard in the embedded space: MXM. It stands for “Mobile PCI Express Module”, and is basically intended as a GPU interface for laptops with PCIe, but there’s way more to it – it can work for any high-power high-throughput PCIe device, with a fair few DisplayPort links if you need them!

You will see MXM sockets in older generations of laptops, barebones desktop PCs, servers, and even automotive computers – certain generations of Tesla cars used to ship with MXM-socketed Nvidia GPUs! Given that GPUs are in vogue today, it pays to know how you can get one in low-profile form-factor and avoid putting a giant desktop GPU inside your device.

I only had a passing knowledge of the MXM standard until a bit ago, but my friend, [WifiCable], has been playing with it for a fair bit now. On a long Discord call, she guided me through all the cool things we should know about the MXM standard, its history, compatibility woes, and hackability potential. I’ve summed all of it up into this article – let’s take a look!

This article has been written based on info that [WifiCable] has given me, and, it’s also certainly not the last one where I interview a hacker and condense their knowledge into a writeup. If you are interested, let’s chat!

Continue reading “MXM: Powerful, Misused, Hackable” →

Unraveling The Secrets Of Apple’s Mysterious Fisheye Format

April 18, 2024 by 11 Comments

Apple has developed a proprietary — even mysterious — “fisheye” projection format used for their immersive videos, such as those played back by the Apple Vision Pro. What’s the mystery? The fact that they stream their immersive content in this format but have provided no elaboration, no details, and no method for anyone else to produce or play back this format. It’s a completely undocumented format and Apple’s silence is deafening when it comes to requests for, well, anything to do with it whatsoever.

Probably those details are eventually forthcoming, but [Mike Swanson] isn’t satisfied to wait. He’s done his own digging into the format and while he hasn’t figured it out completely, he has learned quite a bit and written it all up on a blog post. Apple’s immersive videos have a lot in common with VR180 type videos, but under the hood there is more going on. Apple’s stream is DRM-protected, but there’s an unencrypted intro clip with logo that is streamed in the clear, and that’s what [Mike] has been focusing on.

Most “fisheye” formats are mapped onto square frames in a way similar to what’s seen here, but this is not what Apple is doing.

[Mike] has been able to determine that the format definitely differs from existing fisheye formats recorded by immersive cameras. First of all, the content is rotated 45 degrees. This spreads the horizon of the video across the diagonal, maximizing the number of pixels available in that direction (a trick that calls to mind the heads in home video recorders being tilted to increase the area of tape it can “see” beyond the physical width of the tape itself.) Doing this also spreads the center-vertical axis of the content across the other diagonal, with the same effect.

There’s more to it than just a 45-degree rotation, however. The rest most closely resembles radial stretching, a form of disc-to-square mapping. It’s close, but [Mike] can’t quite find a complete match for what exactly Apple is doing. Probably we’ll all learn more soon, but for now Apple isn’t saying much.

Videos like VR180 videos and Apple’s immersive format display stereoscopic video that allow a user to look around naturally in a scene. But to really deliver a deeper sense of presence and depth takes light fields.