Fail Of The Week: Car Starter Motors Aren’t The Best Fit For EBikes

April 14, 2023 by Dan Maloney 40 Comments

A lot of what real engineering is all about is designing to the limits of your materials, with a healthy margin for error. On the other hand, seat-of-the-pants engineering often takes the opposite tack — working with the materials you have and finding their limits after the fact. While the former is more rigorous and better suited to anything where life and limb are on the line, there’s something to be said for the flexibility that informal engineering offers.

[Austin Blake]’s latest eBike is a case study in informal engineering. [Austin] started out wondering if a starter motor from a car engine would make a decent electric bike motor. Our first instinct before watching the video below was to answer that question with a resounding “No!” Yes, starter motors seem like a natural for the job, delivering high torque in a compact package. But starting a car engine is the very definition of a low-duty-cycle application, since it should only take a second or two of cranking to get an engine started. Pressing a motor designed for such a task into continuous duty seems like, well, a non-starter.

And to be fair, [Austin] fully acknowledges this from the start. He even retrofits the motor, wisely replacing the shaft bushings with proper bearings in an attempt to get a better duty cycle. And it works, at least for a while — with the motor, a homebrew battery, and an ESC mounted to a bike frame, the bike was actually pretty peppy. But bearings aren’t the only thing limiting a starter motor to intermittent duty operation. The short drive really heated up the motor, and even with a few ventilation holes knocked in the motor housing, it eventually released the Magic Smoke. The video has all the gory details.

As always, we like to stress that “Fail of the Week” is not necessarily a badge of shame. We appreciate it whenever someone shows us the way not to go, as [Austin] did here. And let’s keep in mind that he’s had success with this approach before, albeit with a much, much bigger starter motor.

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Retro Gadgets: The 1983 Pocket Oscilloscope

April 14, 2023 by Al Williams 29 Comments

In the 1980s, an oscilloscope was typically a bulky affair with a large CRT, and a heavy power supply. So it probably grabbed a lot of attention in 1983 when Calvert Instruments Incorporated ran an ad in magazines like Radio Electronics. The ad touted a 5 MHz scope that was pocket-sized and weighed 4 ounces. The ad proudly proclaimed: CRT oscilloscopes just became obsolete!

Indeed they would, but if you are wondering who Calvert Instruments was, so are we. We have never heard of them before or since, and we don’t know for certain if any of these devices were ever actually produced. What did it use instead of a CRT? The CI Model 210 Pocket-O-Scope was not only solid state but used an LED screen 1.5 inches square. That’s small, but it packed in 210 LEDs for “high resolution.” We assume that was also the genesis of the model number. Judging from the product picture, there were 14 LEDs in the X direction and 15 in the Y direction. High resolution, for sure!

There were some early LCD scopes (like the Iskrascope and one from Scopex) around the same time, but it would be the 1990s before we would see LCD oscilloscopes and even longer before CRTs were totally squeezed out.

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This Week In Security: QueueJumper, JS VM2 Escape, And CAN Hacking

April 14, 2023 by Jonathan Bennett 9 Comments

You may not be familiar with the Microsoft Message Queuing (MSMQ) service, a store and forward sort of inter-process and inter-system communication service. MSMQ has become something of a legacy product, but is still available as an optional component in Windows. And in addition to other enterprise software solutions, Microsoft Exchange turns the service on by default. That’s why it’s a bit spooky that there’s a one packet Remote Code Execution (RCE) vulnerability that was just patched in the service.

CVE-2023-21554, also known as QueueJumper, is this unauthenticated RCE with a CVSS score of 9.8. It requires sending a packet to the service on TCP port 1801. The Check Point Research team scanned for listening MSMQ endpoints on the public Internet, and found approximately 360,000 of them. And no doubt far more are listening on internal networks. A one packet exploit is a prime example of a wormable problem, and now that the story has broken, and the patch is available, expect a rapid reverse engineering. Beware, the queue jumpers are coming.

JavaScript VM Escape

The VM2 library is a rather important JavaScript package that sandboxes code, letting a project run untrusted code securely. Or, that’s the idea. CVE-2023-29017 is an example of how hard sandboxing is to get right. It’s another CVSS 9.8 vulnerability, and this one allows a sandbox escape and code execution.

This one now has public Proof of Concept code, and this package has over 16 million monthly installs, so the attack surface is potentially pretty wide. The flaw is fixed in version 3.9.15. Continue reading “This Week In Security: QueueJumper, JS VM2 Escape, And CAN Hacking” →

Tinkercad Gets A Move On

April 13, 2023 by Al Williams 22 Comments

Going to the movies is an experience. But how popular do you think they’d be if you went in, bought your popcorn, picked your seat, and the curtain would rise on a large still photograph? Probably not a great business model. If a picture is worth 1,000 words, then a video is worth at least a million, and that’s why we thought it was awesome that Tinkercad now has a physics simulator built right in.

Look for this icon on the top right toolbar.

It all starts with your 3D model or models, of course. Then there’s an apple icon. (Like Newton, not like Steve Jobs.) Once you click it, you are in simulation mode. You can select objects and make them fixed or movable. You can change the material of each part, too, which varies its friction, density, and mass. There is a play button at the bottom. Press it, and you’ll see what happens. You can also share and you have the option of making an MP4 video like the ones below.

We, of course, couldn’t resist. We started with a half-sphere and made it larger. We also rotated it so the flat side was up. We then made a copy that would become the inside of our bowl. Using the ruler tool, we shaved about 2 mm off the length and width (X and Y) of the inner sphere. We also moved it 2 mm up without changing the size.

Using the alignment tools, you can then center the inner piece in the X and Y axis. Change the inner color to a hole and group the objects. This forms a simple bowl shape. Then we moved the workplane to a random part of the inner surface of our bowl and dropped a sphere. Nothing complicated.

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Signed Distance Functions: Modeling In Math

April 12, 2023 by Matthew Carlson 13 Comments

What if instead of defining a mesh as a series of vertices and edges in a 3D space, you could describe it as a single function? The easiest function would return the signed distance to the closest point (negative meaning you were inside the object). That’s precisely what a signed distance function (SDF) is. A signed distance field (also SDF) is just a voxel grid where the SDF is sampled at each point on the grid. First, we’ll discuss SDFs in 2D and then jump to 3D.

SDFs in 2D

A signed distance function in 2D is more straightforward to reason about so we’ll cover it first. Additionally, it is helpful for font rendering in specific scenarios. [Vassilis] of [Render Diagrams] has a beautiful demo on two-dimensional SDFs that covers the basics. The naive technique for rendering is to create a grid and calculate the distance at each point in the grid. If the distance is greater than the size of the grid cell, the pixel is not colored in. Negative values mean the pixel is colored in as the center of the pixel is inside the shape. By increasing the size of the grid, you can get better approximations of the actual shape of the SDF. So, why use this over a more traditional vector approach? The advantage is that the shape is represented by a single formula calculated at many points. Most modern computers are extraordinarily good at calculating the same thing thousands of times with slightly different parameters, often using the GPU. GLyphy is an SDF-based text renderer that uses OpenGL ES2 as a shader, as discussed at Linux conf in 2014 . Freetype even merged an SDF renderer written by [Anuj Verma] back in 2020. Continue reading “Signed Distance Functions: Modeling In Math” →

Analog Anoraks: The Op Amp Contest Starts Now!

April 11, 2023 by Elliot Williams 28 Comments

We thought it was time to give the analog side of Hackaday their chance to shine, and what’s the quintessential analog IC? The op amp! Whether you’re doing tricky signal conditioning, analog computations like it’s 1960, or just making music sound good, op amps are at the heart of many designs. This contest, starting right now, is your chance to show off what you can do with a good op amp, or a few.

And for everyone else, here’s your chance to dip your toes into the warm analog waters. Whether you’ve always wanted to build a Chua’s chaos circuit or just to listen to music, there’s probably an op-amp project that will fit your personal bill. All you have to do to enter is set up a project on Hackaday.io, and use the pull-down menu to enter. We welcome shows of op-amp bravado, naturally, but we’re also stoked to see your simple projects that might help our digital friends leave their world of black and white, and enter into the shades of grey.

Thanks to Digi-Key, our sponsor for the challenge, there are three $150 shopping sprees on the line for the winners. And as always, there are some honorable mention categories to help whet your analog whistle, and to give us an excuse to feature a lot of great projects. You’ve got until June 6, to get your entry in, but these aren’t necessarily simple builds, so get going now.

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A Miniature MNT For Every Pocket

April 11, 2023 by Kerry Scharfglass 35 Comments

Last time Hackaday went hands on with a product from German company MNT, it was the Reform laptop; a full size computer with a full feature set and fully open source design. Now they’re back with the same value proposition and feature set crammed into a much more adorable (and colorful!) package with the MNT Pocket Reform. If you want the big Reform’s open source philosophy in a body fit for a coat pocket, this might be the computing device for you.

To refresh your memory, MNT is a company that specializes in open source hardware and the software to support it. They are probably best known for the Reform, their first laptop. Its marquis feature is a fully open design, from the mechanical components (designed with OSS tools) to the PCBAs (designed with KiCad) to the software (designed with, uh, software). When originally shipped that product packed a DIMM-style System On Module (SOM) with a default configuration containing a quad core NXP i.MX8M Quad and 4GB of RAM, as well as mini PCIe Card and M key m.2 2280 slots on the motherboard for storage and connectivity. That computer was designed to be easily serviceable and included a plethora of full sized ports along with easy to source cylindrical battery cells. The Pocket Reform takes the same intent and channels it into a much smaller package.

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