Keep Coffee Warm Through Induction Heating

April 11, 2021 by Bryan Cockfield 13 Comments

Transformers have an obvious use for increasing or decreasing the voltage in AC systems, but they have many other esoteric uses as well. Electric motors and generators are functionally similar and can be modeled as if they are transformers, but the truly interesting applications are outside these industrial settings. Wireless charging is essentially an air-core transformer that allows power to flow through otherwise empty space, and induction cooking uses a similar principle to induce current flow in pots and pans. And, in this case, coffee mugs.

[Sajjad]’s project is an effort to keep his coffee warm while it sits on his desk. To build this special transformer he places his mug inside a coil of thick wire which is connected to a square wave generator. A capacitor sits in parallel with the coil of wire which allows the device to achieve resonance at a specific tuned frequency. Once at that frequency, the coil of wire efficiently generates eddy currents in the metal part of the coffee mug and heats the coffee with a minimum of input energy.

While this project doesn’t work for ceramic mugs, [Sajjad] does demonstrate it with a metal spoon in the mug. While it doesn’t heat up to levels high enough to melt solder, it works to keep coffee warm in a pinch if a metal mug isn’t available. He also plans to upgrade it so it takes up slightly less space on his desk. For now, though, it can easily keep his mug of coffee hot while it sits on his test bench.

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Smart Lid Spies On Sourdough Starter, Sends Data Wirelessly

March 4, 2021 by Donald Papp 16 Comments

[Justin Lam] created a wonderfully-detailed writeup of his Smart Sourdough Lid project, which was created out of a desire to get better data on the progress and health of his sourdough starters, and to do so more efficiently. The result is a tidy, one-piece lid that constantly measures temperature, humidity, and height of the starter in the jar. Data is sent wirelessly for analysis, but there is also a handy OLED display on the top of the lid that shows immediately useful data like how much the starter has peaked, and how much time has passed since it did so.

The PCB was optimized for size, and not designed with mounting in mind, so a hot-glued machine screw serves as a “button extender”. Issues like this can happen when enclosures are designed after the fact; it’s something to which we can all relate.

We really like how focused the design is, and the level of detail [Justin] goes into to explain his design decisions and describe how well they worked out. This isn’t [Justin]’s first kick at the can when it comes to getting data on his sourdough, after all. We remember his earlier work using computer vision to analyze sourdough starters, and he used what he learned to inform this new design; the smart lid is easier to use and handles data much more efficiently.

The project’s GitHub repository has all the information needed to build your own. The lid is ESP8266-based and integrates a VL6180X time-of-flight (ToF) distance sensor, DHT22 to sense temperature and humidity, and a small SSD1306 OLED display for data. A small custom PCB keeps the modules tidy, and a 3D-printed custom enclosure makes it one tidy package.

[Justin] also analyzes the results he obtained and talks about what they mean in the last part of his writeup, so if you’re into baking and interested in his findings, be sure to give that a look.

How To Bake Brownies With A Perfect Glossy Skin

February 14, 2021 by Lewin Day 35 Comments

If you’re anything at all like this writer, you don’t spend a lot of time inspecting brownies past the initial object identification phase, preferring to insert them directly into the mouth post-haste. But those with more of an aesthetic focus take great care to produce brownies with a glossy, attractive skin. [Adam Ragusea] decided to find out what it takes to get a perfect brownie skin, time after time.

After many, many trays of brownies, [Adam], with the assistance of [Dr. Pia Sörensen], determined that the key seems to be making a brownie mixture with very finely dissolved sugar, in sucrose form, with a carefully controlled amount of water in the mixture. This produces a thick mixture which can hold together against the gases bubbling out during the cooking process, and produces a nice glossy skin. Too much water, and the mixture isn’t viscous enough to hold up, leading to brownies full of pock marks, while alternative sugars like fructose and glucose likely disrupt the ordered structure of sucrose molecules necessary for a shiny surface.

Together, [Adam] and [Pia] do a great job of exploring the molecular chemistry behind the process, as well as ruling out several myths that have been perpetuated in the viciously insular brownie subculture. All they’re missing is a set of standardised reflectivity tests executed with an Arduino and some photodiodes, but we’ll assume that was just cut for time. We’ve seen other hacks in the realm of molecular gastronomy before, like this homebrew kitchen centrifuge. Video after the break.

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Spinach Photo Prints

February 13, 2021 by Brian McEvoy 14 Comments

Some people like spinach in their salads. Others would prefer it if it never gets near their fork. Still, other folks, like [Almudena Romero], use it for printing pictures, and they’re the folks we’ll focus on today.

Anthotypes are positive images made from plant dyes that fade from light exposure. Imagine you stain your shirt at a picnic and leave it in the sun with a fork covering part of the stain. When you come back, the stain not sheltered by cutlery is gone, but now you have a permanent fork shape logo made from aunt Bev’s BBQ sauce. The science behind this type of printmaking is beautifully covered in the video below the break. You see, some plant dyes are not suitable for light bleaching, and fewer still if you are not patient since stains like blueberry can take a month in the sun.

The video shows how to make your own plant dye, which has possibilities outside of anthotype printing. Since the dye fades in sunlight, it can be a temporary paint, or you could use samples all over your garden to find which parts get lots of sunlight since the most exposed swatches will be faded the most. Think of a low-tech UV meter with logging, but it runs on spinach.

If the science doesn’t intrigue you, the artistic possibilities are equally cool. All the pictures have a one-of-a-kind, wabi-sabi flare. You take your favorite photo, make it monochrome, print it on a transparent plastic sheet, and the ink will shield the dye and expose the rest. We just gave you a tip about finding the sunniest spot outdoors, so get staining.

Anthotype printing shares some similarities with etch-resist in circuit board printing processes, but maybe someone can remix spinach prints with laser exposure!

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Would You Like Fries With Your Insect Burger, Ma’am?

February 10, 2021 by Jenny List 167 Comments

A trip to a supermarket is a rare luxury in a pandemic lockdown, but were I to cruise the aisles with my basket today I’d probably come away with a healthy pile of fruit and veg, a bit of meat and fish, and maybe some cheese. My shopping basket in 2031 though might have a few extras, and perhaps surprisingly some of them might be derived from insects. That’s a future made a little closer, by EU scientists declaring that farmed insect products are safe for humans and animals to eat.

Global map showing meat consumption in 2013 — Is meat consumption at this level sustainable? Our World In Data, CC BY 3.0.

We humans, like some of our fellow great ape cousins, are omnivores. We can eat anything, even if we might not always want to eat some things twice. As such, the diets of individual populations would in the past have varied hugely depending on the conditions that existed wherever they lived, giving us the ability to spread to almost anywhere on the planet — and we have.

Over the past few hundred years this need to subsist only on foods locally available has been marginalized by advances in agriculture. For those of us in developed countries, any foodstuff that takes our fancy can be ours for a trivial effort. This has meant an explosion of meat consumption as what was once a luxury food has become affordable to the masses, and in turn a corresponding agricultural expansion to meet demand that has placed intolerable stresses on ecosystems and is contributing significantly to global warming. It’s very clear that a mass conversion to veganism is unlikely to take place, so could farmed insects be the answer to our cravings for meat protein? It’s likely to be a tough sell to consumers, but it’s a subject that bears more examination. Continue reading “Would You Like Fries With Your Insect Burger, Ma’am?” →

Machine Learning In The Kitchen Makes For Tasty Mashup Desserts

February 3, 2021 by Kristina Panos 21 Comments

What did you do during lockdown? A whole lot of people turned to baking in between trips to the store to search for toilet paper and hand sanitizer. Many of them baked bread for some reason, but like us, [Sara Robinson] turned to sweeter stuff to get through it.

The first Cakie ever made. Image via Google Cloud

Her pandemic ponderings wandered into the realm of baking existentialist questions, like what separates baked goods from each other, categorically speaking? What is the science behind the crunchiness of cookies, the sponginess of cake, and the fluffiness of bread?

As a developer advocate for Google Cloud, [Sara] turned to machine learning to figure out why the cookie crumbles. She collected 33 recipes each of cookies, cake, and bread and built a TensorFlow model to analyze them, which resulted in a cookie/cake/bread lineage for each recipe in a set of percentages. Not only was the model able to accurately classify recipes by type, [Sara] was able to use the model to come up with a 50/50 cookie-cake hybrid recipe. The AI delivered a list of ingredients to which she added vanilla extract and chocolate chips for flavor. From there, she had to wing it and come up with her own baking directions for the Cakie.

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NASA Challenge Offers Prizes For Sprouting Astronaut Food Systems

January 25, 2021 by Maya Posch 53 Comments

Humans have unfortunately not yet evolved the ability to photosynthesize or recharge from an electricity source, which is why astronauts well into the future of spaceflight will need to have access to food sources. Developing ways to grow food in space is the focus of the new Deep Space Food Challenge that was just launched by NASA and Canada’s Space Agency (CSA).

With a total of twenty $25,000 USD prizes for US contestants and ten $30,000 CAD prizes for the Canucks in Phase 1 of the challenge, there’s some financial incentive as well. In Phase 2, the winning teams of the concept phase have to show off their kitchen skills, and in the final Phase 3 (deadline by Fall 2023) the full food growing system has to be demonstrated.

The possible systems here would likely involve some kind of hydroponics, aeroponics or even aquaponics, to save the weight of lugging kilograms of soil into space. None of this is truly new technology, but cramming it into a package that would be able to supply a crew of four with enough food during a three-year mission does seem fairly challenging.

The NASA rules are covered in their Phase 1 Rules PDF document. While international teams are also welcome to compete, they cannot receive any prizes beyond recognition, and Chinese citizens or companies with links to China are not to allowed to compete at all.