Mini Cheetah Clone Teardown, By None Other Than Original Designer

December 19, 2022 by Donald Papp 21 Comments

[Ben Katz] designed the original MIT Mini Cheetah robot, which easily captured attention and imagination with its decidedly un-robotic movements and backflips. Not long after [Ben]’s masters thesis went online, clones of the actuators started to show up at overseas sellers, and a few months after that, clones of the whole robot. [Ben] recently had the opportunity to disassemble just such a clone by Dogotix and see what was inside.

Amusingly, one of the first things he noticed is that the “feet” are still just off-the-shelf squash balls, same as his original mini cheetah design. As for the rest of the leg, inside is a belt that goes past some tensioners, connecting the knee joint to an actuator in the shoulder.

As one may expect, these parts are subject to a fair bit of stress, so they have to be sturdy. This design allows for slender yet strong legs without putting an actuator in the knee joint, and you may recall we’ve seen a similar robot gain the ability to stand with the addition of a rigid brace.

It’s interesting to read [Ben]’s thoughts as he disassembles and photographs the unit, and you’ll have to read his post to catch them all. But in the meantime, why not take a moment to see how a neighbor’s curious sheep react to the robot in the video embedded below? The robot botches a backflip due to a low battery, but the sheep seem suitably impressed anyway.

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What’s Inside A Super-Cheap Projector? Not A Lot!

December 18, 2022 by Donald Papp 39 Comments

[Raymond Ma] has a penchant for browsing Aliexpress and purchasing curious pieces of hardware that are as high on promises as they are low on cost. This is a process he aptly sums up with his opening line of “I should have known better, but…” Luckily, these devices all get torn down and analyzed so we can each enjoy and share a little slice of disappointment.

One such item is the $30 USD YT200 mini projector, which at 320×180 is almost as low on pixels as it is on cost. Still, [Raymond] looks inside to find out if there is perhaps more hacking potential than there is image resolution.

The YT200 lacks any kind of normal video input, and the anemic 15 lumen output is brazenly branded as a feature to protect children’s eyes from excessive brightness.

Light from the single LED is collimated with some Fresnel lenses. That light passes through an LCD panel, and from there the image bounces off a mirror and through a focusing lens housed in a spiral guide. Focal adjustments are made with a small lever, and the whole assembly provides just enough friction to prevent the lens from moving out of focus on its own.

The device actually does work fairly well for what it is: a way to play a range of different media types off a connected USB storage device. As long as one is in a dark room, anyway.

[Raymond] hopes to find some alternate use for the device. Might we suggest projecting into a frosted glass globe to create a sort of spherical display? A spooky eye animation on a USB stick might pair well with that.

Sonos Speakers Free To Sing Again

December 15, 2022 by Chris Lott 69 Comments

Over at the EEVBlog, [Dave Jones] takes a second look at the Sonos Play 5 Gen 1 that he rescued from the dumpster recently. Despite being solidly built, [Dave] discovered that even the stereo line-in jack can’t be used without registering an account with Sonos. Not to be defeated, he hacks these speakers to make them work standalone.

Bluetooth Audio Amplifier Module (Fosi Audio)

The hack here involves fitting the speaker cabinet with new “guts” in the form of a wireless stereo 2×50 watt digital amplifier [Dave] found online for under $30. This particular model, the Fosi TB21, is almost a perfect fit for the Sonos cabinet — with only minimal Dremel tool encouragement required. It turned out the power supply section of the Sonos main board was easy to isolate. [Dave] couldn’t use the existing amplifiers, so he removed them from their power supply and re-routed the power supply to the Fosi module. He also removed the Sonos wireless interface board from the cabinet, and used an online design tool to make a simple first order Butterworth crossover network set to 2800 Hz to connect the speakers.

The new amplifier board is mounted in the shallow base of the speaker cabinet. It could have easily been oriented either way, but [Dave] chose to install it knobs-forward. This also gave him a reason to toss out the Sonos badge. The resulting modified unit looks very professional, and works well as a Bluetooth speaker for the lab.

We wrote about the opposite conversion last year, where old speakers from the 1960s were hacked to add Sonos capability. You can read about the controversy surrounding Sonos here, and we discussed the issue on the Hackaday Podcast in episode 058.

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The Story Behind The TVGuardian Curse Catcher

December 14, 2022 by Chris Lott 23 Comments

The recent flurry of videos and posts about the TVGuardian foul language filter brought back some fond memories. I was the chief engineer on this project for most of its lifespan. You’ve watched the teardowns, you’ve seen the reverse engineering, now here’s the inside scoop.

Gumby is Born

TVG Model 101 Gumby (Technology Connections)

Back in 1999, my company took on a redesign project for the TVG product, a box that replaced curse words in closed-captioning with sanitized equivalents. Our first task was to take an existing design that had been produced in limited volumes and improve it to be more easily manufactured.

The original PCB used all thru-hole components and didn’t scale well to large quantity production. Replacing the parts with their surface mount equivalents resulted in Model 101, internally named Gumby for reasons long lost. If you have a sharp eye, you will have noticed something odd about two parts on the board as shown in [Ben Eater]’s video. The Microchip PIC and the Zilog OSD chip had two overlapping footprints, one for thru-hole and one for SMD. Even though we preferred SMD parts, sometimes there were supply issues. This was a technique we used on several designs in our company to hedge our bets. It also allowed us to use a socketed ICs for testing and development. Continue reading “The Story Behind The TVGuardian Curse Catcher” →

Portable Commodore 64 Lives!

November 27, 2022 by Al Williams 17 Comments

When you think of a luggable computer, you might think of the old Compaq or — if you are old enough — a Kaypro. But you don’t see as many Commodore SX-64 computers. [The 8-Bit Guy] has wanted one for a while and finally got one, but it wasn’t working. No problem! Just fix it!

The device actually looks sleek compared to some other portables of the era and had a color screen, but — probably due to the price — they didn’t sell very well. The outside of the device looked pretty clean other than some loose screws and clips. The space key was quite yellow but at least there was a keyboard cable which is nearly impossible to find anymore.

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Detecting Radiation For Fun And Profit

November 9, 2022 by Al Williams 19 Comments

It used to be that every well-stocked doomsday bunker had a Geiger counter. These days, you don’t have to have a big tube-based meter. You can inexpensively get a compact digital instrument to handle your radiation detection needs. [DiodeGoneWild] reviews and tears down such a unit from FNIRSI. The case looks like several other similar instruments we’ve seen lately, so presumably, someone is mass-producing these handheld meter cases. You can see the video, below. The meter reads the absolute radioactivity and can also measure cumulative exposure.

After measuring a few common radioactive items, we get to the teardown. Inside, of course, is an ordinary tube. A few screws reveal a typical rechargeable battery, a fairly simple PCB with a microcontroller and battery backup for the real-time clock. A lot of the board is involved in multiplying voltage up to the several hundred volts required for the Geiger tube.

The other side of the PCB has only buttons, a vibration motor, and, of course, the LCD. We don’t know how you might test the relative accuracy other than comparing it to a known-good meter. The bare tube was, of course, more sensitive without the plastic cover, but that could be calibrated out, too.

A Geiger counter doesn’t have to have a lot of parts. Either way, a surprising number of things will set them off.

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Look Inside This “Meditation Headband” And Integrate It Into Your Own Projects

October 23, 2022 by Donald Papp 10 Comments

Muse makes a variety of wearable devices aimed at measuring brain and body activity, and [Becky Stern] did a detailed teardown of the Muse S model, revealing what goes on inside the device.

The Muse S is a soft, sleep-friendly biofeedback wearable mounted on silver-plated fabric. Not only does [Becky] tear it down, but she provides loads of magnified images and even has it CT scanned. The headband has conductive fabric embedded into it, and the core of the device is stuffed with three separate PCBs that get pretty thoroughly scrutinized.

While the Muse S is sold mainly as a meditation aid and works with a companion app, there is, fortunately, no need to go digging around with a screwdriver and soldering iron to integrate it into other projects. The Muse S is supported by the Brainflow project which opens it up to different applications. Brainflow is a library intended to obtain, parse, and analyze EEG, EMG, ECG, and other kinds of data from biosensors.

If you think Muse and Brainflow sound familiar, that might be because of another project we featured that integrated a Muse 2 and Brainflow with Skyrim VR, creating a magic system whose effectiveness depends on the player’s state of mind. Good things happen when hardware and software are accessible to users, after all.

You can watch a video tour of the teardown in the video, embedded just under the page break.

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