Adding Automatic Emergency Braking To An RC Car

July 2, 2025 by 1 Comment

Modern RC cars can be pretty darn fast. That’s fun and all, but it also makes it easy to crash them into things. This problem inspired [Narrow Studios] to whip up something to offer a bit of protection.

The concept is simple enough—the RC car just needs some way to detect obstacles and stop before hitting them. The build relies on ultrasonic sensors as rangefinders to spot solid objects in the path of the vehicle. An Arduino Nano is in charge of reading the sensors. When it appears the car is approaching a wall or similar obstacle, it fires off a PWM signal to the car’s motor controller commanding it to brake. The additional hardware is held to the car with a bunch of custom printed brackets.

The setup isn’t perfect; the video notes that if you insist on accelerating quickly when close to a wall, you still have a fair chance of hitting it. That’s largely put down to the refresh time of the sensors and the overall system, which could be improved with further work. Still, if you’re always crashing your RC car into walls or curbs, this kind of thing might appeal to you.

We’ve featured some other great RC projects before, too.

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Whack-A-Disk

July 1, 2025 by 11 Comments

By now most floppy disks have been relegated to the dustbin of history, with a few exceptions for obscure industrial applications using legacy hardware and, of course, much of the world’s nuclear weapons arsenals. In fact, they’re so rare to see in the world anymore that many below a certain age don’t recognize the “save” symbol commonly used in application user interfaces. Without a use case, and with plenty of old floppies still laying around, [Rob] took a pile of them and built this Whack-a-Mole-style game.

The game has a number of floppy-disk-specific features compared to the arcade classic, though. First, there’s no mallet, so the player must push the floppy disks into the drive manually. Second, [Rob] went to somewhat exceptional lengths to customize the drives to that sometimes the disks jump out of the drive, forcing the player to grab them and put them back in to score points in the game. He did this without needing to install high-powered solenoids in the drives too. As for the game software itself, it all runs on an Amiga 600 and even includes a custom-made soundtrack for the 30-second game.

Getting the drives just right did take a number of prototypes, but after a few versions [Rob] has a working game that looks fun to play and is a clever use of aging hardware, not to mention the fact that it runs on a retro computer as well. Of course, for the true retro feel, you’ll want to make sure you find a CRT for the display somewhere, even though they’re getting harder to find now than old floppy disk drives.

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Challenge: Square A Voltage

July 1, 2025 by 18 Comments

Your design task, should you decide to accept it: given an input voltage, square it. Ok, that’s too hard since squaring 8 volts would give you 64 volts, so let’s say the output should be 10% of the square, so 8 volts in would result in 6.4V. How do you do it? [Engineering Prof.] knows how and will show you what you can do in the video below.

The circuit uses two op amps and some transistors. However, the transistors are used in a way that depends on the temperature, so it is important to use a transistor array so they are matched and will all be at the same temperature.

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A Crypto Miner Takes The Straight And Narrow

July 1, 2025 by 29 Comments

As it stands, cryptocurrency largely seems to be a fad of the previous decade, at least as far as technology goes. During that time, many PC users couldn’t get reasonably priced graphics cards since most of them were going into these miners. In contrast, nowadays any shortages are because they’re being used to turn the Internet into an AI-fueled wasteland. But nonetheless, there is a lot of leftover mining hardware from the previous decade and unlike the modern AI tools getting crammed into everything we own, this dated hardware is actually still useful. [Zendrael] demonstrates this by turning an old mining rig into a media server.

The mining rig is essentially nothing more than a motherboard with a large number of PCI slots, each designed for a GPU. PCI slots can do many other things, though, so [Zendrael] puts a terabyte solid state drive in each but one of the PCI cards using NVMe to PCI adapters. The final slot still hosts a GPU since the computer is being converted to a media server, and this allows it to do various encodings server-side. Even with only 4 GB of memory, the machine in its new configuration is more than capable of running Debian and spinning up all of the necessary software needed for a modern media server like Jellyfin, Nextcloud, and Transmission.

With many people abandoning miners as the value of them declines over time, it’s possible to find a lot of hardware like this that’s ready to be put to work on something new and useful. Hopefully all of the GPUs and other hardware being put to use today in AI will find a similar useful future, but until then we’ll note that you don’t need super powerful hardware to run some of those models on your own.

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There Are Better Lego-Compatible Universal Joints Out There

July 1, 2025 by 11 Comments

Lego’s Technic line features all kinds of mechanical devices, from cogs to gears to chains and even pneumatic components. However, the vast majority of these components are made out of plastic and are only capable of toy-like levels of performance. In the competitive world of Lego YouTube, builders often push these parts to their limits, breaking them more often than you might think. To that end, [Brick Experiment Channel] has been investigating stouter Lego-compatible universal joints from a variety of third-party manufacturers.

The video starts with a simple demonstration, showing that a Lego universal joint pops apart at just 0.4 Nm of torque. It’s no surprise, given it relies on tiny plastic pins in snap-fit joints. However, this means that it’s not that hard to build a stronger universal joint to outperform the stock parts.

The video steps through a range of other options available on the market. For example, CaDA builds a universal joint using aluminium sleeves, a copper center, and steel pins to join everything together. It’s so strong that the plastic Lego axles fail long before the joint does. Tested with third-party aluminum axles, it eventually fails at 2.3 Nm of torque when the aluminum sleeve snaps. An all-steel joint from MTP goes even harder, eventually stripping out its axle mount at 4 Nm. The rest of the video goes on to explore angular performance, size, and other design features.

It’s fair to say that if you’re swapping out universal joints and axles for aluminum steel parts, you’re not really playing with Lego anymore. At the same time, it’s neat that there exists a sort of defacto standard kit for mechanical experimentation that is now being expanded upon with stronger components. Video after the break.

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Fingers installing a service loop in a wire in a connector

Are Service Loops A Good Idea?

July 1, 2025 by 23 Comments

Well, here’s an interesting idea: the service loop. Ever heard of it? We haven’t!

In the video, the presenter explains the service loop serves two purposes: on the one hand it may provide strain relief, but chiefly these loops are installed so there will be extra available slack in the cable if you need to rewire it some day to change the configuration of your pinout.

One major problem with the service loop may be that the single turn is enough to create an inductor which will then induce noise and cross-talk all over the place. Our rule of thumb is always to completely unroll wires and cables before using them. Do you have a theory about the benefits or problems with service loops? If you do, we’d love to hear what you think in the comments!

If you’re interested in strain relief, we’ve covered that before, and you don’t need a service loop to do it! Check out Cheap Strain Relief By Casting Hot Glue In A 3D Print and Arduino Uno Strain Relief.

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The rust language logo being branded onto a microcontroller housing

C++ Encounters Of The Rusty Zig Kind

July 1, 2025 by 87 Comments

There comes a time in any software developer’s life when they look at their achievements, the lines of code written and the programming languages they have relied on, before wondering whether there may be more out there. A programming language and its associated toolchains begin to feel like familiar, well-used tools after you use them for years, but that is no excuse to remain rusted in place.

While some developers like to zigzag from one language and toolset to another, others are more conservative. My own journey took me from a childhood with QuickBasic and VisualBasic to C++ with a bit of Java, PHP, JavaScript, D and others along the way. Although I have now for years focused on C++, I’m currently getting the hang of Ada in particular, both of which tickle my inner developer in different ways.

Although Java and D never quite reached their lofty promises, there are always new languages to investigate, with both Rust and Zig in particular getting a lot of attention these days. Might they be the salvation that was promised to us C-afflicted developers, and do they make you want to zigzag or ferrously oxidize?

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