Ideal Diodes And How To Build Them

[Julian] knows that real diodes you can buy don’t work exactly like we say they do. That’s actually pretty common. We routinely ignore things like wire resistance and source resistance in batteries. Diodes have problems that are harder to ignore, such as the forward voltage drop. So, while a real diode will only pass current in one direction, it will also drop some of the voltage. [Julian] shows you how you can get simulated ideal diodes and why you might want them in a recent video you can see below.

The video starts with a simple demonstration and enumerates some of the practical limitations. Then, he pulls out some ideal diode modules. These typically don’t solve every problem, so they aren’t really ideal in the theoretical sense. But they typically appear to have no forward voltage drop.

Continue reading “Ideal Diodes And How To Build Them”

Fundamentals Of FMCW Radar Help You Understand Your Car’s Point Of View

Pretty much every modern car has some driver assistance feature, such as lane departure and blind-spot warnings, or adaptive cruise control. They’re all pretty cool, and they all depend on the car knowing where it is in space relative to other vehicles, obstacles, and even pedestrians. And they all have another thing in common: tiny radar sensors sprinkled around the car. But how in the world do they work?

If you’ve pondered that question, perhaps after nearly avoiding rear-ending another car, you’ll want to check out [Marshall Bruner]’s excellent series on the fundamentals of FMCW radar. The linked videos below are the first two installments. The first covers the basic concepts of frequency-modulated continuous wave systems, including the advantages they offer over pulsed radar systems. These advantages make them a great choice for compact sensors for the often chaotic automotive environment, as well as tasks like presence sensing and factory automation. The take-home for us was the steep penalty in terms of average output power on traditional pulsed radar systems thanks to the brief time the radar is transmitting. FMCW radars, which transmit and receive simultaneously, don’t suffer from this problem and can therefore be much more compact.

Continue reading “Fundamentals Of FMCW Radar Help You Understand Your Car’s Point Of View”

Inside The RLL Hard Drive Protocol

If you are younger than a certain age, RLL probably doesn’t mean much to you. Old consumer-grade hard drives used MFM (modified frequency modulation like a floppy disk uses) and soon went to IDE (integrated drive electronics). There was a brief period when RLL (run length limited) drives were the way to get a little more life out of the MFM technology. [W1ngsfly] has an RLL drive on his bench and uses his scope and some other gear to put it through its paces. You can watch over his shoulder in the video below.

The hardware interface and drive are the same for an MFM and an RLL drive. However, an RLL-aware controller can pack more bits on the same platter by using the newer modulation scheme. Some older disks were good enough for MFM but too sloppy to successfully take an RLL format, but — in theory — any MFM drive could be an RLL drive and vice versa.

Continue reading “Inside The RLL Hard Drive Protocol”

Make Your Own Remy The Rat This Halloween

[Christina Ernst] executed a fantastic idea just in time for Halloween: her very own Remy the rat (from the 2007 film Ratatouille). Just like in the film Remy perches on her head and appears to guide her movements by pulling on hair as though operating a marionette. It’s a great effect, and we love the hard headband used to anchor everything, which also offers a handy way to route the necessary wires.

Behind Remy are hidden two sub-micro servos, one for each arm. [Christina] simply ties locks of her hair to Remy’s hands, and lets the servos do the rest. Part of what makes the effect work so well is that Remy is eye-catching, and the relatively small movements of Remy’s hands are magnified and made more visible in the process of moving the locks of hair.

Originally Remy’s movements were random, but [Christina] added an MPU6050 accelerometer board to measure vertical movements of her own arm. She uses that sensor data to make Remy’s motions reflect her own. The MPU6050 is economical and easy to work with, readily available on breakout boards from countless overseas sellers, and we’ve seen it show up in all kinds of projects such as this tiny DIY drone and self-balancing cube.

Want to make your own Remy, or put your own spin on the idea? The 3D models and code are all on GitHub and if you want to see more of it in action, [Christina] posts videos of her work on TikTok and Instagram.

[via CBC]

A Robust Guide To The Xbox 360 Glitch Hack

The Xbox 360 was a difficult console to jailbreak. Microsoft didn’t want anyone running unsigned code, and darn if they didn’t make it difficult to do so. However, some nifty out of the box thinking and tricky techniques cracked it open like a coconut with a crack in it. For the low down, [15432] has a great in-depth article on how it was achieved. The article is in Russian, so you’ll want to be armed with Google Translate for this one.

The article gets right into the juice of how glitch attacks work—in general, and with regards to the Xbox 360. In the specific case of the console, it was all down to the processor’s RESET line. Flicker it quickly enough, and the processor doesn’t actually reset, but nonetheless its behavior changes. If you time the glitch right, you can get the processor to continue running through the bootloader’s instructions even if a hash check instruction failed. Of course, timing it right was hard, so it helps to temporarily slow down the processor.

From there, the article continues to explore the many and varied ways this hack played out against Microsoft’s copy protection across multiple models and revisions of the Xbox 360. The bit with the BGA ball connections is particularly inspired. [15432] also goes even deeper into a look at how the battle around the Xb0x 360’s DVD-ROM drive got heated.

We seldom talk about the Xbox 360 these days, but they used to grace these pages on the regular. Video after the break.

Continue reading “A Robust Guide To The Xbox 360 Glitch Hack”

Hackaday Hacked!

Well, that was “fun”. Last week, we wrote a newsletter post about the state of Hackaday’s comments. We get good ones and bad ones, and almost all the time, we leave you all up to your own devices. But every once in a while, it’s good to remind people to be nice to our fellow hackers who get featured here, because after all they are the people doing the work that gives us something to read and write about. The whole point of the comment section is for you all to help them, or other Hackaday readers who want to follow in their footsteps.

Someone decided to let loose a comment-reporting attack. It works like this: you hit the “report comment” button on a given comment multiple times from multiple different IP addresses, and our system sends the comments back to moderation until a human editor can re-approve them. Given the context of an article about moderation, most everyone whose comment disappeared thought that we were behind it. When more than 300 comments were suddenly sitting in the moderation queue, our weekend editors figured something was up and started un-flagging comments as fast as they could. Order was eventually restored, but it was ugly for a while.

We’ve had these attacks before, but probably only a handful of times over the last ten years, and there’s basically nothing we can do to prevent them that won’t also prevent you all from flagging honestly abusive or spammy comments. (For which, thanks! It helps keep Hackaday’s comments clean.) Why doesn’t it happen all the time? Most of you all are just good people. Thanks for that, too!

But despite the interruption, we got a good discussion started about how to make a comment section thrive. A valid critique of our current system that was particularly evident during the hack is that the reported comment mechanism is entirely opaque. A “your comment is being moderated” placeholder would be a lot nicer than simply having the comment disappear. We’ll have to look into that.

You were basically divided down the middle about whether an upvote/downvote system like on Reddit or Slashdot would serve us well. Those tend to push more constructive comments up to the top, but they also create a popularity contest that can become its own mini-game, and that’s not necessarily always a good thing. Everyone seemed pretty convinced that our continuing to allow anonymous comments is the right choice, and we think it is simply because it removes a registration burden when someone new wants to write something insightful.

What else? If you could re-design the Hackaday comment section from scratch, what would you do? Or better yet, do you have any examples of similar (tech) communities that are particularly well run? How do they do it?

We spend our time either writing and searching for cool hacks, or moderating, and you can guess which we’d rather. At the end of the day, our comments are made up of Hackaday readers. So thanks to all of you who have, over the last week, thought twice and kept it nice.

Power Supply PCB Redesign

We’ve often heard you should do everything twice. The first time is to learn what you need to do, and the second time is to do it right. We bet [Ian Carey] would agree after taking his old linear power supply PCB and changing it to a switching regulator design. You can see more about the project in the video below.

The first power-up revealed a problem with the 3.3V output. We’ve often thought it is harder to troubleshoot a new design than it is to repair something that is known to have worked at one time.

Continue reading “Power Supply PCB Redesign”