How To Turn Cheap Speakers Into Something A Little Better

July 5, 2024 by 25 Comments

[Adam Francis] bought some cheap speaker drivers from AliExpress. Are they any good? Difficult to tell without a set of enclosures for them, so he made a set of transmission line cabinets. The resulting video proves that a decent sounding set of speakers shouldn’t have to cost the earth, and is quite entertaining to watch.

The design he’s going for is a transmission line, in effect a folded half-wave resonant tube terminated at one end and open at the other, with the speaker close to half way along. There is a lot of nuance to perfecting a speaker cabinet, but this basic recipe doesn’t have to be optimum to give a good result.

So after having some MDF cut to shape and glueing it all together, he ends up with some semi decent speakers for not a lot of money. The video is entertaining, with plenty of Britishisms, but the underlying project is sound. We’d have a pair on our bench.

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Useless Robot Gets Cute, Has Personality

July 4, 2024 by 4 Comments

Useless robots (or useless machines) are devices that, when switched on, exist only to turn themselves back off. They are fun and fairly simple builds that are easy to personify, and really invite customization by their creators. Even so, [tobychui]’s Kawaii Useless Robot goes above and beyond in that regard. Not only will his creation dutifully turn itself off, but if the user persists in engaging it, Kawaii Useless Robot grows progressively (and adorably) upset which ultimately culminates in scooting about and trying to run away.

If anything, it gets cuter when upset.

This is actually a ground-up re-imagining of an original work [tobychui] saw from a Japanese maker twelve years ago. That original Kawaii Useless Robot did not have any design details, so [tobychui] decided to re-create his own.

Behind the laser-cut front panel is a dot matrix LED display made up of eight smaller units, and inside are a total of four motors, an ESP32 development board, and supporting electronics. A neat touch is the ability to allow connections over Wi-Fi for debugging or remote control. The project page has some nice photos of the interior that are worth checking out. It’s a very compact and efficient build!

Watch it in action in the video (embedded below) which also includes a tour of the internals and a thorough description of the functions.

Inspired to make your own useless machine? Don’t be afraid to re-invent the whole concept. For example, we loved the one that physically spins the switch and the clock that falls to the floor when it detects someone looking at it. That last one is a close relative of the clock that displays the wrong time if and only if someone is looking.

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Cavity Filters, The Black Art You Have A Chance Of Pursuing

July 4, 2024 by 12 Comments

A tuned circuit formed by a capacitor and an inductor is a familiar enough circuit, and it’s understood that it will resonate at a particular frequency. As that frequency increases, so the size of the capacitor and inductor decrease, and there comes a point at which they can become the characteristic capacitance and inductance of a transmission line. These tuned circuits can be placed in an enclosure, at which they can be designed for an extremely high Q factor, a measure of quality, and thus a very narrow resonant point. They are frequently used as filters for that reason, and [Fesz] is here with a video explaining some of their operation and configurations.

Some of the mathematics behind RF design can be enough to faze any engineer, but he manages to steer a path away from that rabbit hole and explain cavity filters in a way that’s very accessible. We learn how to look at tuned circuits as transmission lines, and the properties of the various different coupling methods. Above all it reveals that making tuned cavities is within reach.

They’re a little rare these days, but there was a time when almost every TV set contained a set of these cavities which were ready-made for experimentation.

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Shapeways Files For Bankruptcy

July 4, 2024 by 37 Comments

One of the earliest hobbyist-friendly on-demand 3D printing and fabrication shops, Shapeways, is filing for bankruptcy. As these financial arrangements always go, this may or may not mean the end of the service, but it’s a sure sign that their business wasn’t running as well as you’d hope.

One of the standout features of Shapeways was always that they made metal printing affordable to the home gamer. Whether it was something frivolous like a custom gear-shifter knob, or something all-too functional like a prototype rocket engine, it was neat to have the alternative workflow of iterative design at home and then shipping out for manufacturing.

We don’t want to speculate too much, but we’d be surprised if the rise of similar services in China wasn’t part of the reason for the bankruptcy. The market landscape just isn’t what it was way back in 2013. (Sadly, the video linked in this article isn’t around any more. If anyone can find a copy, post up in the comments?) So while Shapeways may or may not be gone, it’s not like we can’t get metal parts made anymore.

Still, we’re spilling a little for the OG.

Thanks [Aaron Eiche] for the breaking news tip!

A small 3D-printed printing press with a print that says THE QUICK BROWN FOX JUMPED OVER THE LAZY BROWN DOG.

Mini 3D-Printed Press Is Sure To Make An Impression

July 4, 2024 by 9 Comments

Making stamps out of potatoes that have been cut in half is always a fun activity with the kids. But if you’ve got a 3D printer, you could really step up your printing game by building a mini relief printing press.

To create the gear bed/rack, [Kevr102] used a Fusion 360 add-in called GF Gear Generator. At first this was the most finicky part of the process, but then it was time to design the roller gears. However, [Kevr102] got through it with some clever thinking and a little bit of good, old-fashioned eyeballing.

Per [Kevr102], this press is aimed at the younger generation of printers in that the roller mechanism is spring-loaded to avoid pinched fingers. [Kevr102] 3D-printed some of the printing tablets, which is a cool idea. Unfortunately it doesn’t work that well for some styles of text, but most things came out looking great. You could always use a regular linocut linoleum tile, too.

This isn’t the first 3D-printed printing press to grace these pages. Here’s one that works like a giant rubber stamp.

A Cute Sentry Scans Your Net For Scullduggery

July 4, 2024 by 10 Comments

As long as we get to make our own network security tools, why not make them look cute? Netgotchi may not be much more than an ESP8266 running network scans and offering up a honeypot service, but it smiles while sits on your desk and we think that’s swell.

Taking inspiration from a recent series of red-team devices that make hacking adorable, most obviously pwnagotchi (and arguably Flipper), Netgotchi lives on the light side of the Force. Right now, it enumerates the devices on your network and can alert you when anything sketchy joins in. We can totally imagine customizing this to include other network security or health checks, and extending the available facial expressions accordingly.

You might not always be thinking about your network, and if you’re like us, that’s probably just fine. But we love standalone displays that show one thing in an easily digestable manner, and this fits the bill, with a smile.

Cloudflare Adds Block For AI Scrapers And Similar Bots

July 4, 2024 by 19 Comments

It’s no big secret that a lot of the internet traffic today consists out of automated requests, ranging from innocent bots like search engine indexers to data scraping bots for LLM and similar generative AI companies. With enough customers who are less than amused by this boost in useless traffic, Cloudflare has announced that it’s expanding its blocking feature for the latter category of scrapers. Initially this block was only for ‘poorly behaving’ scrapers, but now it apparently targets all of such bots.

The block seems to be based around a range of characteristics, including the user agent string. According to Cloudflare’s data on its network, over 40% of identified AI bots came from ByteDance (Bytespider), followed by GPTBot at over 35% and ClaudeBot with 11% and a whole gaggle of smaller bots. Assuming that Imperva’s claims of bots taking up over half of today’s internet traffic are somewhat correct, that means that even if these bots follow robots.txt, that is still a lot of bandwidth being drained and the website owner effectively subsidizing the training of some company’s models. Unsurprisingly, Cloudflare notes that many website owners have already taken measures to block these bots in some fashion.

Naturally, not all of these scraper bots are well-behaved. Spoofing the user agent is an obvious way to dodge blocks, but scraper bot activity has many tell-tale signs which Cloudflare uses, as well as statistical data across its global network to compute a ‘bot score‘ for any requests. Although it remains to be seen whether false positives become an issue with Cloudflare’s approach, it’s definitely a sign of the times that more and more website owners are choosing to choke off unwanted, AI-related traffic.