Just a pile of strawberries.

Can You Freeze-Dry Strawberries Without A Machine?

June 20, 2024 by 45 Comments

Summer has settled upon the northern hemisphere, which means that it’s time for sweet, sweet strawberries to be cheap and plentiful. But would you believe they taste even better in freeze-dried format? I wouldn’t have ever known until I happened to get on a health kick and was looking for new things to eat. I’m not sure I could have picked a more expensive snack, but that’s why we’re here — I wanted to start freeze-drying my own strawberries.

While I could have just dropped a couple grand and bought some kind of freeze-drying contraption, I just don’t have that kind of money. And besides, no good Hackaday article would have come out of that. So I started looking for alternative ways of getting the job done.

Dry Ice Is Nice

Dry ice, sublimating away in a metal measuring cup.
Image via Air Products

Early on in my web crawling on the topic, I came across this Valley Food Storage blog entry that seems to have just about all the information I could possibly want about the various methods of freeze-drying food. The one that caught my eye was the dry ice method, mostly because it’s only supposed to take 24 hours.

Here’s what you do, in a nutshell: wash, hull, and slice the strawberries, then put them in a resealable bag. Leave the bag open so the moisture can evaporate. Put these bags in the bottom of a large Styrofoam cooler, and lay the dry ice on top. Loosely affix the lid and wait 24 hours for the magic to happen.

I still had some questions. Does all the moisture simply evaporate? Or will there be a puddle at the bottom of the cooler that could threaten my tangy, crispy strawberries? One important question: should I break up the dry ice? My local grocer sells it in five-pound blocks, according to their site. The freeze-drying blog suggests doing a pound-for-pound match-up of fruit and dry ice, so I guess I’m freeze-drying five entire pounds of strawberries. Hopefully, this works out and I have tasty treats for a couple of weeks or months. Continue reading “Can You Freeze-Dry Strawberries Without A Machine?” →

McDonald’s Terminates Its Drive-Through Ordering AI Assistant

June 18, 2024 by 71 Comments

McDonald’s recently announced that it will be scrapping the voice-assistant which it has installed at over 100 of its drive-throughs after a two-year trial run. In the email that was sent to franchises, McDonald’s did say that they are still looking at voice ordering solutions for automated order taking (AOT), but it appears that for now the test was a disappointment. Judging by the many viral videos of customers struggling to place an order through the AOT system, it’s not hard to see why.

This AOT attempt began when in 2019 McDonald’s acquired AI company Apprente to create its McD Tech Labs, only to sell it again to IBM who then got contracted to create the technology for McDonald’s fast-food joints. When launched in 2021, it was expected that McDonald’s drive-through ordering lanes would eventually all be serviced by AOT, with an experience akin to the Alexa and Siri voice assistants that everyone knows and loves (to yell at).

With the demise of this test at McDonald’s, it would seem that the biggest change is likely to be in the wider automation of preparing fast-food instead, with robots doing the burger flipping and freedom frying rather than a human. That said, would you prefer the McD voice assistant when going through a Drive-Thru® over a human voice?

A closeup of the ring, inner electronics including a lit green LED seen through the inner transparent epoxy, next to the official app used to light up the LED for a demo.

New Part Day: A Hackable Smart Ring

June 16, 2024 by 35 Comments

We’ve seen prolific firmware hacker [Aaron Christophel] tackle smart devices of all sorts, and he never fails to deliver. This time, he’s exploring a device that seems like it could have come from the pages of a Cyberpunk RPG manual — a shiny chrome Bluetooth Low Energy (BLE) smart ring that’s packed with sensors, is reasonably hacker friendly, and is currently selling for as little as $20.

The ring’s structure is simple — the outside is polished anodized metal, with the electronics and battery carefully laid out along the inside surface, complete with a magnetic charging port. It has a BLE-enabled MCU, a heartrate sensor, and an accelerometer. It’s not much, but you can do a lot with it, from the usual exercise and sleep tracking, to a tap-sensitive interface for anything you want to control from the palm of your hand. In the video’s comments, someone noted how a custom firmware for the ring could be used to detect seizures; a perfect example of how hacking such gadgets can bring someone a brighter future.

The ring manufacturer’s website provides firmware update images, and it turns out, you can upload your own firmware onto it over-the-air through BLE. There’s no signing, no encryption — this is a dream device for your purposes. Even better, the MCU is somewhat well-known. There’s an SDK, for a start, and a datasheet which describes all you would want to know, save for perhaps the tastiest features. It’s got 200 K of RAM, 512 K of flash, BLE library already in ROM, this ring gives you a lot to wield for how little space it all takes up. You can even get access to the chip’s Serial Wire Debug (SWD) pads, though you’ve got to scrape away some epoxy first.

As we’ve seen in the past, once [Aaron] starts hacking on these sort of devices, their popularity tends to skyrocket. We’d recommend ordering a couple now before sellers get wise and start raising prices. While we’ve seen hackers build their own smart rings before, it’s tricky business, and the end results usually have very limited capability. The potential for creating our own firmware for such an affordable and capable device is very exciting — watch this space!

Continue reading “New Part Day: A Hackable Smart Ring” →

A clipping of the "3D Printing & Modelling" skill tree. An arrow pointing up says "Advanced" and there are several hexagons for various skills on the page including blanks for writing in your own options and some of the more advanced skills like "Print in Nylon or ASA material"

Maker Skill Trees Help You Level Up Your Craft

June 11, 2024 by 12 Comments

Hacking and making are great fun due to their open ended nature, but being able to try anything can make the task of selecting your next project daunting. [Steph Piper] is here with her Maker Skill Trees to give you a map to leveling up your skills.

Featuring a grid of 73 hexagonal tiles per discipline, there’s plenty of inspiration for what to tackle next in your journey. The trees start with the basics at the bottom and progressively move up in difficulty as you move up the page. With over 50 trees to select from (so far), you can probably find something to help you become better at anything from 3D printing and modeling to entrepreneurship or woodworking.

Despite being spoiled for choice, if you’re disappointed there’s no tree for your particular interest (underwater basket weaving?), you can roll your own with the provided template and submit it for inclusion in the repository.

Want to get a jump on an AI Skill Tree? Try out these AI courses. Maybe you could use these to market yourself to potential employers or feel confident enough to strike out on your own?

[Thanks to Courtney for the tip!]

Continue reading “Maker Skill Trees Help You Level Up Your Craft” →

Raspberry Pi Goes Public

June 11, 2024 by 57 Comments

We’ve heard rumors for the last few months, and now it looks like they’ve come true: the business side of Raspberry Pi, Raspberry Pi Holdings has become a publicly listed company on the London Stock Exchange.

We heard rumblings about this a while back, and our own [Jenny List] asked the question of what this means for the hobbyist and hacker projects that use their products. After all, they’ve been spending a lot of money making new silicon, and issuing stock helps them continue. Jenny worried that they’d forget that what sells their hardware is the software, but ends up concluding that they’ll probably continue doing more of the same thing, just with better funding.

Raspberry Pi CEO [Eben Upton] said basically the same when we asked him what a floatation would mean for the Raspberry Pi Foundation, which is the non-profit arm of the Raspberry Empire, and which is responsible for a lot of the educational material and outreach that they do. (Fast-forward to minute 40.) Before the share issue, the Foundation wholly owned Holdings, and received donations to fund its work. Now that there has been a floatation, it looks like the Foundation will owns 70% of Holdings, and will use this endowment to finance its educational mission.

We don’t have a crystal ball, but we suspect this changes not much at all. Raspberry Pi Holdings Ltd is doing great business by producing niche single-board computers that appeal both to the hacker and industrial markets, and the Raspberry Pi Foundation now has a more concrete source of funding to continue its educational goals. But the future will tell!

Switching Regulator Layout For Dummies

June 10, 2024 by 43 Comments

Last time, we went over switching regulator basics – why they’re wonderful, how do you find a switching regulator chip for your purpose, and how to easily pick an inductor for one. Your datasheet should also tell you about layout requirements. However, it might not, or you might want to deviate from them – let’s go more in-depth on what those requirements are about.

Appreciate The Feedback

The two resistors on the right decide what your output voltage will be, and their output is noise-sensitive

There’s a few different switching regulator topologies. Depending on your regulator’s topology and how many components your chip contains, you might need some external components – maybe a Schottky diode, maybe a FET, or maybe even a FET pair. It’s often that the FET is built-in, and same goes for diodes, but with higher-current regulator (2 A to 3 A and above), it’s not uncommon to require an external one. For sizing up those, you’ll want to refer to the datasheet or existing boards.

Another thing is input and output capacitors – don’t skimp on those, because some regulators are seriously sensitive to the amount of capacitance they’re operating with. Furthermore, if you fail to consider things like capacitance dropping with voltage, you might make your regulator very unhappy – not that a linear regulator would be happy either, to be clear. We’ve covered an explainer on this recently – do check it out!

One thing you will likely need, is a feedback resistor divider – unless your switching regulator is pre-set for a certain voltage or is digitally controlled, you need to somehow point it to the right voltage, in an analog way. Quite a few switching regulators are set for a certain voltage output, but most of them aren’t, and they will want you to add a resistor divider to know what to output. There’s usually a formula for resistor divider calculation, so, pick a common resistor value, put it in as one of the resistors into the formula, get the other resistor value out of that formula, and see what’s the closest value you can actually buy. Don’t go below about 10 kΩ so that you don’t have unnecessary idle power consumption, but also don’t go too far above 100 kΩ to ensure good stability of the circuit. Continue reading “Switching Regulator Layout For Dummies” →

The Dyke Delta: A DIY Flying Wing Fits Four

June 4, 2024 by 24 Comments

The world of experimental self-built aircraft is full of oddities, but perhaps the most eye-catching of all is the JD-2 “Dyke Delta” designed and built by [John Dyke] in the 1960s. Built to copy some of the 1950’s era innovations in delta-style jet aircraft, the plane is essentially a flying wing that seats four.

And it’s not just all good looks: people who have flown them say they’re very gentle, they get exceptional gas mileage, and the light wing-loading means that they can land at a mellow 55 miles per hour (88 kph). And did we mention the wings fold up so you can store it in your garage?

Want to build your own? [John] still sells the plans. But don’t jump into this without testing the water first — the frame is entirely hand-welded and he estimates it takes between 4,000 and 5,000 hours to build. It’s a labor of love. Still, the design is time-tested, and over 50 of the planes have been built from the blueprints. Just be sure to adhere to the specs carefully!

It’s really fun to see how far people can push aerodynamics, and how innovative the experimental airplane scene really is. The JD-2 was (and probably still is!) certainly ahead of its time, and if we all end up in flying wings in the future, maybe this plane won’t look so oddball after all.

Continue reading “The Dyke Delta: A DIY Flying Wing Fits Four” →