Can You Freeze-Dry Strawberries Without A Machine?

June 20, 2024 by Kristina Panos 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?” →

A persistence-of-vision business card which displays information when shaken (not stirred).

2024 Business Card Challenge: Make Them Shake Your Handiwork

June 11, 2024 by Kristina Panos 2 Comments

Before COVID, people traditionally sealed their initial introduction to each other with a handshake. Nowadays, that activity seems kind of questionable. But you can still give them something to shake if you build this persistence of vision (POV) business card from [chaosneon] to show your credentials in blinkenlights form.

As you might have guessed, the input comes from a tilt switch. The user simply shakes the card back and forth, and the sensor detects the direction and cadence of the shake. Cleverly, the pattern plays forward-ways on the swing, and backwards on the back stroke, which just reinforces the POV effect. Don’t worry about how slow or fast to shake it, because the timing adjusts for your speed.

The first version used individual white LEDs, hand-soldered to an ATtiny2313. Now, in the updated version which you can see in the demo video after the break, [chaosneon] is using an RGB NeoPixel strip, which only needs one data wire to connect to the microcontroller. Thanks to this, [chaosneon] was able to to downsize to an ATtiny85.

Continue reading “2024 Business Card Challenge: Make Them Shake Your Handiwork” →

A business card-sized, solar-powered weather station.

2024 Business Card Challenge: Weather Or Not You Get The Job

June 11, 2024 by Kristina Panos 6 Comments

What’s the easiest way to break the ice with someone you’ve just met? If you’re not immediately talking shop, than it’s probably the time-tested subject of the weather. So what better way to get the conversation started than with a lovely solar-powered circuit sculpture of a business card that displays the weather?

We love that the frame has a built-in stand; that’s a great touch that really turns this card into something that someone might keep on their desk long-term. The brains of this operation is an ESP32 TTGO E-paper board, which checks the battery voltage first before connecting to Wi-Fi and getting data from the OpenWeatherMap API. It displays the information and then goes to sleep for 15 minutes.

For power, [BLANCHARD Jordan] is using a 5 V solar panel and a small battery from an old vape pen. We love to see projects that keep those things out of the landfills, so don’t sleep on using them.

You have just a few weeks left to enter the 2024 Business Card Challenge, so fire up those soldering irons and get hackin’!

A business card-sized love detector in a 3D-printed package.

2024 Business Card Challenge: Who Do You Love?

June 10, 2024 by Kristina Panos 5 Comments

When you hand your new acquaintance one of your cards, there’s a chance you might feel an instant connection. But what if you could know almost instantly whether they felt the same way? With the Dr. Love card, you can erase all doubt.

As you may have guessed, the card uses Galvanic Skin Response. That’s the fancy term for the fact that your skin’s electrical properties change when you sweat, making it easier for electricity to pass through it. There are two sensors, one on each short end of the card where you would both naturally touch it upon exchange. Except this time, if you want to test the waters, you’ll have to wait 10-15 seconds while Dr. Love assesses your chemistry.

The doctor in this case is an RP2040-LCD-0.96, which is what it sounds like — a Raspberry Pi Pico with a small LCD attached. For the sensors, [Un Kyu Lee] simply used 8mm-wide strips of nickel. If you want to build your own, be sure to check out the build guide and watch the video after the break for a demonstration of Dr. Love in action.

Continue reading “2024 Business Card Challenge: Who Do You Love?” →

8-Tracks Are Back? They Are In My House

June 10, 2024 by Kristina Panos 56 Comments

What was the worst thing about the 70s? Some might say the oil crisis, inflation, or even disco. Others might tell you it was 8-track tapes, no matter what was on them. I’ve heard that the side of the road was littered with dead 8-tracks. But for a while, they were the only practical way to have music in the car that didn’t come from the AM/FM radio.

If you know me at all, you know that I can’t live without music. I’m always trying to expand my collection by any means necessary, and that includes any format I can play at home. Until recently, that list included vinyl, cassettes, mini-discs, and CDs. I had an 8-track player about 20 years ago — a portable Toyo that stopped working or something. Since then, I’ve wanted another one so I can collect tapes again. Only this time around, I’m trying to do it right by cleaning and restoring them instead of just shoving them in the player willy-nilly.

Update: I Found a Player

A small 8-track player and equally small speakers, plus a stack of VHS tapes. — I have since cleaned it.

A couple of weeks ago, I was at an estate sale and I found a little stereo component player and speakers. There was no receiver in sight. I tested the player with the speakers and bought them for $15 total because it was 75% off day and they were overpriced originally. While I was still at the sale, I hooked it up to the little speakers and made sure it played and changed programs.

Well, I got it home and it no longer made sound or changed programs. I thought about the play head inside and how dirty it must be, based on the smoker residue on the front plate of the player. Sure enough, I blackened a few Q-tips and it started playing sweet tunes again. This is when I figured out it wouldn’t change programs anymore.

I found I couldn’t get very far into the player, but I was able to squirt some contact cleaner into the program selector switch. After many more desperate button presses, it finally started changing programs again. Hooray!

I feel I got lucky. If you want to read about an 8-track player teardown, check out Jenny List’s awesome article. Continue reading “8-Tracks Are Back? They Are In My House” →

A stack of PCB business cards that can play Snake on an 8x8 LED matrix.

2024 Business Card Challenge: Snakes On A Business Card

June 2, 2024 by Kristina Panos No comments

Once [Lambert the Maker] saw the Arduboy, he knew the thing was ripe for remixing into a business card with an 8×8 LED matrix instead of an OLED screen. [Lambert] already has a PCB business card for work, but it looks like it doesn’t do anything. So this Snake-playing card is for their personal information.

The brains of this operation is an STM32F0, which required a bit of finesse when it came to programming the LEDs. According to the datasheet, the max current through a given GPIO pin is 30 mA. The LEDs are running at 20 mA through the limiting resistor, so the code only turns on one LED at a time and makes sure the previous one is off first. The whole screen is updated every 125 ms, and persistence of vision takes care of making the animation look right.

In the short videos after the break, you’ll see a preview followed by brief videos on versions one and two. The prototype was built in 2020, when the board house only offered green PCBs with their assembly service. Fast forward to 2024, when the board house is now offering colors other than green.

Version two is actually thinner than a credit card, and features tiny buttons instead of cap-sense pads for input. [Lambert] also added a floating ADC pin that acts as a random number generator, placing the apple in a new location every time the game is powered on.

Continue reading “2024 Business Card Challenge: Snakes On A Business Card” →

A small internet radio in 3D-printed case with a knob and an OLED screen.

GlobeTune Will Widen Your Musical Horizons

June 1, 2024 by Kristina Panos 12 Comments

Are you tired of the same old music, but can’t afford any new tunes, even if they’re on dead formats? Boy, do we know that feeling. Here’s what you do: build yourself a GlobeTune music player, and you’ll never want for new music again.

The idea is simple, really. Just turn what we assume is a nice, clicky knob, and after a bit of static (which is a great touch!), you get a new, random radio station from somewhere around the globe. [Alexis D.] originally built this as a way to listen to and discover new music while disconnecting from the digital world, and we think it’s a great idea.

[Alexis D.] has production in mind, so after a Raspberry Pi Zero W prototype, they set about redesigning it around the ESP32. The current status seems to be hardware complete, software forthcoming. [Alexis D.] says that a crowdfunding campaign is in the works, but that the project will be open-sourced once in an acceptable state. So stay tuned!

Speaking of dead-ish formats, here’s an Internet radio in a cassette form factor.