Author: Al Williams

4450 Articles

A RISC-V Security Key

December 26, 2023 by 6 Comments

The TKey is a RISC-V-based security key that plugs into a USB port. The device has a number of features, including a device-specific serial number, RAM scrambling, and a monitor that kills the CPU in the event of access to protected memory. There is also an FPGA that, on the end-user version, is locked down. This prevents you from changing the core features and the unique ID number for the device.

As part of the start-up code, the device calculates a hash of the application and merges it with the device ID and, potentially, a user-defined secret. If this number matches a previous calculation, it is reasonably certain that nothing has changed between the times of the calculations.

Continue reading “A RISC-V Security Key” →

Restoring The DC Bias

December 26, 2023 by 1 Comment

If you have a signal that passes through a capacitor or transformer, you will lose the DC portion of the signal. What do you do? If you need it, you can restore the DC bias using various techniques, as [Sam Ben-Yaakov] shows in a recent video.

These types of circuits were common in analog TVs, and, in fact, [Sam] shows the schematic of a TV to explain the need for the DC level. In that case, a vacuum tube diode does the work, but a solid state one will do the same job.

Continue reading “Restoring The DC Bias” →

Open Source Scanner Scans The Slides

December 26, 2023 by 9 Comments

What do you get when you join a slide projector and a digital camera? Filmolimo, an open source slide scanner. The scanner uses an M5Stack Fire, an ESP32 development board. Thanks to the ESP32, you can control the device via WiFi.

All the project files, including KiCAD design files, are on GitHub. Of course, you will probably have to adapt things to your specific camera and slide projector. The PCB is double-sided and looks easy to put together. The board is mostly opto-isolation and interface between the controller and the equipment. The software allows you to change things like the time between slides, for example.

This is one of those projects you probably only need for a bit. Unless, of course, you regularly scan slides. You can farm it out to a service provider, but what fun is that? If you have a few hundred thousand slides, you might need to go for speed. If you just have a few, you can get by with a simple adapter.

The Tech That Died In 2023

December 25, 2023 by 26 Comments

We don’t indulge too often in looking back, but [Chloe Albanesisu] at PC Magazine did and wrote the tech obituary for all the tech gadgets and services that died over this past year. Some of the entries are a bit predictable: Twitter died to be replaced by X, which is exactly like it, only different. Others we hardly noticed, like Netflix stopping its DVD shipments.

Google Glass died again, but this time it was the enterprise edition. Amazon gave up on both donating money through shopping and print subscriptions via Kindle.

Glass wasn’t the only Google casualty. Gmail lost its basic HTML version and shut down its smart whiteboard product, Jamboard. They also sold off their Internet domain business in an effort to focus on core businesses. Other notable Google shutdowns include their popular podcast app and Usenet support for Groups. Oh, and don’t forget their experiment in offering Pixels phones as a subscription. That’s done, too.

As you might expect, PC Magazine’s list is a bit consumer-oriented. What hacker-centric products and services vanished this year that you’ll miss? The Sculpteo Marketplace? XYZ Printing? Start up companies collapsed in 2023 at an alarming rate, but you didn’t hear about most of them. Were there any you were especially disappointed about? Let us know in the comments.

3D Printing With Plastic Cutlery

December 25, 2023 by 18 Comments

How many plastic spoons, knives, and forks do you think we throw away daily? [Stefan] noted that the compostable type is made from PLA, so why shouldn’t you be able to recycle it into 3D printing stock? How did it work? Check it out in the video below.

[Stefan] already has a nice setup for extruding filament. However, unsurprisingly, it won’t accept spoons and forks directly. A blender didn’t help, so he used an industrial plastic shredder. It reduced the utensils to what looked like coarse dust, which he then dried out. After running it through the extruder, the resulting filament was thin and brittle. [Stefan] speculates the plastic was set up for injection molding, but it at least showed the concept had merit.

In a second attempt, he cut the ground-up utensils with fresh PLA in equal measures. That is, 50% of the mix was recycled, and half was not. That made much more usable filament. So did a different brand of compostable plasticware.

The real test was to take dirty plasticware. This time, he soaked utensils in tomato sauce overnight. He cleaned, dried, and shredded the plastic. This time, he used 20% new PLA and some pigment, as well. We aren’t sure this is worth the effort simply on economics, but if you are committed to recycling, this might be worth your while.

It always seems like it should be easy to extrude filament. Until you try to do it, of course. Recycling plastic bottles is especially popular.

Continue reading “3D Printing With Plastic Cutlery” →

3D Printing Stacks

December 24, 2023 by 3 Comments

There is a big difference between building one of something and building, say, 100 of the same item. It isn’t surprising, then, that 3D printing in bulk differs from printing one object at a time. Of course, filling up your build plate is not a new idea. But [Keep Making] wants to encourage you to think in three dimensions and fill up your build volume in the Z axis, as well.

When you fill your X and Y axes, it is easy to see how the parts separate. But with stack printing, you must separate the parts from different layers. Each part has a single-layer gap, and the top surfaces are ironed for a better finish. Sometimes the prints may stick, and the video shows how to use a screw to pop off recalcitrant prints. The technique produces one side that isn’t as nice a finish as the other side, but it isn’t bad, and for many applications, you don’t care, anyway.

Before you get too excited about your own designs, you might try a simple test file and get your print settings dialed in. Obviously, if you need just two or three copies of something small, it is easier to step and repeat them across the build surface. But if you need to maximize your throughput or make multiple copies of large objects, this might be the technique for you.

Looks like an interesting technique that doesn’t require you to do anything strange like, say, waterproof your printer. No strings attached.

Continue reading “3D Printing Stacks” →

How Does A Sewing Machine Sew?

December 24, 2023 by 35 Comments

Like all Hackaday readers, we pride ourselves on having at least a passing acquaintance with how most things work. But we suspect to a lot of people, things we take for granted — computers, air conditioning, motors, and cell phones — are just black magic. That’s how we feel about sewing machines. Sure, there’s a motor. There’s a needle and some thread. But how does the machine make a stitch? We always wondered, but after watching a recent video from [Veritasium] we can at least claim we have an idea.

First, he shows the intrinsic problem: sewing by hand requires you to reverse the direction of the needle, and it isn’t clear how to make a simple machine to do that. Sure, today you could probably make a robot that sews like a human does, but sewing machines have been around for a very long time.

In addition to showing how a chain stitch and lock stitch work, the video shows the history of the machines, including 50,000-year-old needles and the progression of innovations required to get to the modern sewing machine. In addition, he shows a large model sewing machine to clearly explain the concepts.

You might think you don’t care about sewing, but machine sewing has touched nearly everyone. The video says that in 1900, a family might spend 15% of their income on clothes. In 2003, that number drops to under 4%, yet the family will have many more clothes than they did in 1900. This is possible because of machine sewing and other innovations.

You can, of course, make your own sewing machine. If you want to get an industrial one, we have some advice.

Continue reading “How Does A Sewing Machine Sew?” →