Google Drive Now Bootable

July 2, 2024 by Bryan Cockfield 22 Comments

USB drives are incredibly useful, both storing files for transport between different computers and for creating bootable drives that let us use or install other operating systems on our computers. While online file storage systems like Dropbox and Google Drive have taken over a large percentage of the former task from USB drives, they have not been able to act as bootable media, ensuring that each of us have a few jump drives lying around. That might not be the case anymore, though, as this guide is the first we know of to be able to use Google Drive to boot to a Linux system.

Unlike the tried-and-true jump drive methods, however, this process is not straightforward at all. It relies on two keys, the first of which is FUSE which allows a filesystem to be created in userspace. The second is exploiting a step in boot process of Linux systems where the kernel unpacks a temporary filesystem, called initramfs, in order to load the real filesystem. Normally a user doesn’t interact much with this step, but that doesn’t mean it’s impossible. A tool called dracut allows using an existing Linux installation to build a custom initramfs and in this case, the custom initramfs is built to include the proper support for both networking and FUSE.

The proof of concept in this demonstration originally ran in a container, using an existing project called google-drive-ocamlfuse to interact with Google Drive itself. From there, after sorting out some issues with root access, networking, malfunctioning symlinks, and various timeouts on the (perhaps predictably) slow system, the whole contraption was moved over to a laptop so it could be tested on real hardware. Everything runs, and although the original creator of this behemoth admits it is a bit “silly” they note that there may be some real-world use cases for something like this. We still won’t expect everyone to throw out their jump drives anytime soon, though. If you’re not feeling like your Linux skills are up to the challenge of something like this, we’d recommend you start with our own [Al Williams]’s Linux Fu series.

Broken Lens Provides Deep Dive Into Camera Repair

May 13, 2024 by Dan Maloney 18 Comments

While most of us are probably willing to pick up the tools and void the warranty on just about anything, often just to see what’s inside, many of us draw the line at camera gear. The tiny screws, the complex mechanisms, and the easily destroyed optical elements are all enough to scare off the average hacker. Not so for [Anthony Kouttron], who tore into a broken eBay Sigma lens and got it working again.

Now, to be fair, modern lenses tend to have a lot more in them that’s amenable to repair than back in the old days. And it seemed from the get-go that [Anthony]’s repair was going to be more electronic than optical or mechanical. The 45-mm lens was in fantastic shape physically, but wouldn’t respond to any controls when mounted to a camera body. Removing the lens bayonet mount exposed the main controller PCB, which is tightly packed with SMD components and connectors for the flex cables that burrow further into the lens to its many sensors and actuators. By probing traces with his multimeter, [Anthony] found a DC-DC converter on the main PCB with an unknown component nearby. This turned out to be an SMD fuse, and as luck would have it, it was open. Replacing the fuse got the lens working again, and while there’s always the nagging suspicion that whatever blew the fuse the first time could happen again, the repair seems to have worked.

Despite the simplicity of the fix, [Anthony] continued the teardown and shared a lot of tips and tricks for lens repairs, including where he would have looked next if the fuse had been good. One tip we loved was the use of double-sided tape to organize parts as they’re removed; this is particularly important with camera gear where screws or different lengths can make for a really bad day on reassembly.

Feeling the need to dive deeper into lens repair? This step-by-step repair should keep you satisfied.

the PTC fuse to blame for the fault described, on the ROG Ally board, with a wire soldered across the fuse

ROG Ally SD Card Slot Fix Shines Light On PTC Fuse Failure Modes

May 4, 2024 by Arya Voronova 9 Comments

The Asus ROG Ally is a handheld that, to our pleasant surprise, has attracted a decently sized modding community. Recently, we’ve stumbled upon a Reddit post investigating a somewhat common failure mode of this handheld — the microSD card slot going out of order, where an inserted card fails to be recognized, pretty irritating to encounter. Now, it turns out, this is down to a certain model of PTC fuses being failure-prone.

It makes sense to fuse the SD card slot. The cards are dense pieces of technology that are subject to some wear and tear in daily use. As such, it’s not unheard of that a microSD card can short-circuit internally — heating up to the point of melting plastic and giving people severe burns. Given that such a card is typically connected to a beefy 3.3 V rail, any mass-manufactured device designer could want to put a fuse between the 3.3 V rail and the card. However, on some ROG Ally batches, a certain make of the fuse is used, that appears to be likely to develop faults: the fuse’s resistance increasing dramatically during the card’s normal operation, with the SD card being supplied subpar power as a result.

There’s a fair bit of investigating happening in the comment section, with people posting oscilloscope captures, using breakouts to tap the SD card, and figuring out the fuse part numbers for the affected models. As for Reddit’s solution, it’s short-circuiting the fuse with a piece of thin wire — we would probably source a suitable fuse and solder it on top of the faulty one.

This isn’t the first ROG Ally modification we’ve covered so far, and given the activity we’re seeing, it’s unlikely to be our last.

Do You Trust Your Cheap Fuses?

April 11, 2024 by Jenny List 33 Comments

When a fuse is fitted in a power rail, it gives the peace of mind that the circuit is protected. But in the case of some cheap unbranded fuses of the type that come in kits from the usual online suppliers that trust can be illusory, as they fail to meet the required specification.

[Andreas Spiess] has used just these fuses for protection for years as no doubt have many of you, so it was something of a shock for him to discover that sometimes they don’t make the grade. He’s taken a look at the issue for himself, and come up with an accessible way to test your fuses if you have any of those cheap ones.

It’s an interesting journey into the way fuses work, as we’re reminded that the value written on the fuse isn’t the current at which it blows but the maximum it’s intended to take. The specification for fuses should have a graph showing how quickly one should blow at what currents above that level, and the worry was that this time would be simply too long for the cheap ones.

In the video below the break, he looks at the various set-ups required to test a fuse, and instead of a bank of large power supplies, he came up with a circuit involving an 18650 cell and three one ohm resistors in parallel. The resulting 1/3 ohm resistor should pass in the region of 10 A when connected across the 18650, so with a 5 A fuse in that circuit and a storage ‘scope he’s able to quickly test a few candidates. He found that the cheap fuses he had were slower to blow than a Bosch part but weren’t as worrisome as he’d at first thought. If you have any of these parts, maybe you should take a look at them too?

Continue reading “Do You Trust Your Cheap Fuses?” →

Resistor Swap Gives Honda Insights More Power

January 31, 2024 by Bryan Cockfield 122 Comments

A common complaint around modern passenger vehicles is that they are over-reliant on electronics, from overly complex infotainment systems to engines that can’t be fixed on one’s own due to the proprietary computer control systems. But even still, when following the circuits to their ends you’ll still ultimately find a physical piece of hardware. A group of Honda Insight owners are taking advantage of this fact to trick the computers in their cars into higher performance with little more than a handful of resistors.

The relatively simple modification to the first-generation Insight involves a shunt resistor, which lets the computer sense the amount of current being drawn from the hybrid battery and delivered to the electric motor. By changing the resistance of this passive component, the computer thinks that the motor is drawing less current and allows more power to be delivered to the drivetrain than originally intended. With the shunt resistor modified, which can be done with either a bypass resistor or a custom circuit board, the only other change is to upgrade the 100 A fuse near the battery for a larger size.

With these two modifications in place, the electric motor gets an additional 40% power boost, which is around five horsepower. But for an electric motor which can output full torque at zero RPM, this is a significant boost especially for a relatively lightweight car that’s often considered under-powered. It’s a relatively easy, inexpensive modification though which means the boost is a good value, although since these older hybrids are getting along in years the next upgrade might be a new traction battery like we’ve seen in the older Priuses.

Thanks to [Aut0l0g1c] for the tip!

A ZX Spectrum Raytracer, In BASIC

January 26, 2024 by Dave Rowntree 12 Comments

[Gabriel Gambetta] knows a few things about ray tracers, being the author of Tiny Raytracer, a raytracer written in just 912 bytes of JavaScript. As a long-time fellow sufferer of the UK-designed ZX Spectrum, could these two love affairs be merged? Could the Tiny Raytracer fit on the ZX Spectrum? In BASIC? The answer is an affirmative, albeit with our beloved speccy’s many limitations.

Ray tracing with only 15 primary colours

The story starts with [Gabriel]’s Computer Graphics From Scratch (CGFS) raytracer algorithms and an existing code base that was ported to the ZX Spectrum’s very limited BASIC dialect, using VSCode for editing, BAS2TAP to generate a tape image file (essentially an audio track) and executed with FUSE. With the toolchain sorted, [Gabriel] adds just enough code to deal with the ray intersection equations of a sphere, and renders a three-sphere scene to a 32×22 pixel colour image, taking a mere 15 minutes of runtime. Fellow sufferers will remember the spectrum had a 32×22 block attribute array (or colour array) with two colour values for foreground and background pixels. Each attribute block contains 8×8 pixels, each of which could be foreground (on) or background (off.) The next stage was then to expand the code to handle pixels as well as blocks, by simply expanding the raytracing to the full 256×176 resolution, and for each block simply determine the two most common colours, and run with those for the whole block. It sort of works, in a very spectrum-esq ‘attribute clash’ kind of fashion.

Continue reading “A ZX Spectrum Raytracer, In BASIC“ →

Just How Dodgy Are Cheap USB Chargers Anyway?

November 3, 2023 by Dan Maloney 49 Comments

Aside from apparently having both the ability to reproduce on their own and simultaneously never being around when you need one, USB chargers seem innocuous enough. The specs are simple: convert mains voltage to 5 volts, and don’t kill anyone while doing it. Both specs are typically met by most designs, but judging by [DiodeGoneWild]’s latest USB charger teardown, the latter only just barely, and with a whole lot of luck.

The sad state of plug-in USB power supplies is one of [DiodeGoneWild]’s pet gripes, and deservedly so. Most USB chargers cram a lot of electronics into a mighty small volume, and are built to a price point, meaning that something has to give in the design. In the case of the two units he tears apart in the video below, it’s pretty clear where the compromises are. Neither unit met the specs on the label in terms of current supplied and voltage regulation, even the apparently more capable quick charger, which is the first to go under the knife. The PCB within holds some alarming surprises, like the minimal physical isolation between the mains part of the circuit and the low-voltage section, but the real treat is the Schottky diode that gets up to 170°C under full load. Safety tip: when you smell plastic burning, throw the thing out.

The second charger didn’t fare any better; although it didn’t overheat, that’s mainly because it shut itself off before it could deliver a fraction of its rated 1 amp output. The PCB construction was shoddy in the extreme, with a squiggly trace standing in for a proper fuse and a fraction of a millimeter separation between primary and secondary traces. The flyback transformer was a treat, too; who doesn’t want to rely on a whisper-thin layer of cheap lacquer to keep mains voltage out of your phone?

All in all, these designs are horrible, and we have to thank [DiodeGoneWild] for the nightmares we’ll have whenever we plug into one of these things from now on. On the other hand, this was a great introduction to switch-mode power supply designs, and what not to do with our own builds. Continue reading “Just How Dodgy Are Cheap USB Chargers Anyway?” →