How To Build A Small Solar Power System

December 30, 2023 by Jenny List 41 Comments

We live in an exciting time with respect to electrical power, one in which it has never been easier to break free from mains electricity, and low-frequency AC power in general. A confluence of lower-power appliances and devices using low-voltage external switch-mode supplies, readily available solar panels and electronic modules, and inexpensive high-capacity batteries, means that being your own power provider can be as simple as making an online order.

But which parts should you choose? Low Tech Magazine has the answer, in the form of a guide to building a small solar power system. The result is an extremely comprehensive guide, and though it’s written for a general audience there’s still plenty of information for the Hackaday reader.

Perhaps the most important part is that it’s demystifying the subject, there in front of us are a set of pretty straightforward recipes for personal power. The computer this is being written on spends a significant proportion of its time on the road with the ever-present company of a very hefty USB-C power pack for example, and the realization that a not-too-expensive solar panel and USB PD source could lessen the range anxiety and constant search for a train seat with a socket for a writer on the move is quite a powerful one.

Take a look and see whether your life could use bit of inexpensive off-grid power, meanwhile we’re quite pleased that the USB-C PD standard has eased some of the DC problems we expressed frustration at back in 2016.

Peltier Mini Fridge For Class By Class

December 30, 2023 by Al Williams 13 Comments

How do you keep a few sodas in your classroom cool? Well, if you are teacher [Ethan Hunt], you have your students design and build a solid-state mini refrigerator that can beat his prototype fridge. The prototype uses a Peltier effect module to get three cans down to 11 C (52 F), with a final goal of reaching 5 C (41 F). It’s not all fun and games either — [Ethan] provides a suggested lesson plan with a total of thirteen modules made to fit in an hour each.

Peltier effect modules, also known as solid-state heat pumps, used to be exotic tech but are now quite common. They are actually the reverse of the Kelvin effect. Thermocouples exploit the Kelvin effect by measuring current flowing due to temperature differences.

Solid-state heat pumps use current flowing to create a comparable temperature difference. However, that’s also the catch. One side of the heat pump gets cold, but the other side gets equally hot. That heat has to go somewhere. The same is true, of course, of a “real” refrigerator or an air conditioner.

The lessons would be perfect to adapt for a class, a kid’s club, or even homeschooling. We’d love to see what your students build. You probably won’t be making liquid nitrogen with this setup. But we have seen more than one mini-fridge.

Sound-Reactive Light Saber Flips Allegiance Via Vowel Sounds

December 29, 2023 by Donald Papp 4 Comments

Students [Berk Gokmen] and [Justin Green] developed an RP2040-based LED-illuminated lightsaber as a final project with a bit of a twist. It has two unusual sound-reactive modes: disco mode, and vowel detection mode.

Switching allegiances (or saber color, at least) is only a sound away.

Disco mode alters the color of the saber dynamically in response to incoming sounds. Color and brightness are altered in response to incoming frequencies picked up by the on-board microphone, making a dynamic light show that responds particularly well to music.

The second mode is vowel detection, and changes the lightsaber’s color depending on spoken sounds. The “ee” sound makes the saber red, and the “ah” sound turns it blue. This method requires a lot of processing and filtering, and in the end it works, but is quite dependent on individual speakers for calibration.

The sound functionality centers around FFTs (Fast Fourier Transforms) which are fundamental to processing signals like audio in a meaningful way, and is a method accessible to embedded devices like microcontrollers with ADCs.

The lightsaber is battery-powered and wireless, and there are loads of details about the finer points of the design (including challenges and tradeoffs) on the project page, and the source code is available on GitHub. A video demonstration and walkthrough is embedded below.

Continue reading “Sound-Reactive Light Saber Flips Allegiance Via Vowel Sounds” →

Edgar Thomson Steel Works in the mid-1990s (Credit: David Rochberg - Own work, CC BY 2.5)

How US Steel Changed From World-Leading To Industry-Trailing

December 29, 2023 by Maya Posch 68 Comments

It was recently announced that US Steel will be acquired by Tokyo-based Nippon Steel for a measly $14.1 billion , ending the former’s 122 year history as a former US industrial powerhouse. Yet what happened to degrade what was once the number one steel maker in the world upon its formation out of two existing industrial giants in 1901 into a has-been? This is the topic that [Brian Potter] dives into in a recent article.

Most of the how and why can be condensed into a simple reluctance to follow industry innovations, often passing on new technologies. This went well until the post-WWII era, when foreign competition began to heat up, with this competition more than happy to embrace whatever new steel making technologies became available. Case in point was the replacement of open hearth furnaces with basic oxygen furnaces by the early 1950s, which US Steel only began to adopt in the 1960s. These were then themselves largely replaced by contemporary electric arc furnaces, in a constant renewal process that US Steel failed to adapt to, unlike its more nimble competitors.

By the early 1980s US Steel’s US market share had already dropped to around 20% as Japanese steel makers in particular were eating its lunch. As US Steel and other US steel makers kept falling behind on the competition, shedding plants and workers in an attempt to stay profitable, it should come as no surprise that this would be US Steel’s ultimate fate.

(top image: Edgar Thomson Steel Works in the mid-1990s (Credit: David Rochberg – Own work, CC BY 2.5) )

Flashlight Door Lock Is A Bright Idea

December 29, 2023 by Kristina Panos 44 Comments

There are many ways to lock a door. You could use a keypad, an RFID card, a fingerprint or retina scan, Wi-Fi, Bluetooth, the list goes on. You could even use a regular old metal key. But none of these may be as secure as [mircemk]’s Arduino-based door lock that employs a smartphone’s flashlight as a pass code.

At first blush, this seems horribly insecure. Use a plain old flashlight to open a door? Come on. But the key is in the software. In fact, between the typed-in pass code and the flash of light it generates, this lock kind of has two layers of security.

Here’s what’s going on: inside the accompanying smart phone application, there’s a list of passwords. Each of these passwords corresponds to a flash of light in milliseconds. Enter the correct password to satisfy the Arduino, and the phone’s flashlight is activated for the appropriate number of milliseconds to unlock the door.

As you’ll see in the video below, simply flashing the light manually doesn’t unlock the door, and neither does entering one of the other, bogus passwords. Although it does activate the flashlight each time, they don’t have the appropriate light-time length defined.

Hardware-wise, there is an Arduino Nano Every in charge of the LDR module that reads the flashlight input and the 12 V relay that unlocks the door. Be sure to check it out it the video after the break.

If you want to keep your critters from bringing wild critters back inside, check out this Wi-Fi cat door that lets you have a look at what might be dangling from their jaws before unlocking the door.

Continue reading “Flashlight Door Lock Is A Bright Idea” →

Gentoo Linux, Now A Bit Less For The 1337

December 29, 2023 by Jenny List 37 Comments

Among users of Linux distributions there’s a curious one-upmanship, depending on how esoteric or hardcore your distro is. Ubuntu users have little shame, while at the other end if you followed Linux From Scratch or better still hand-compiled the code and carved it onto the raw silicon with a tiny chisel, you’re at the top of the tree*. Jokes aside though, it’s fair to say that if you were running the Gentoo distribution you were something of a hardcore user, because its source-only nature meant that everything had to be compiled to your liking. We’re using the past tense here though, because in a surprise announcement, the distro has revealed that it will henceforth also be available as a set of precompiled binary packages.

There may be readers with long and flowing neckbeards who will decry this moment as the Beginning of the End, but while it does signal a major departure for the distro if it means that more people are spurred to take their Linux usage further and experiment with Gentoo, this can never be a bad thing. Gentoo has been on the list for a future Jenny’s Daily Drivers OS review piece, and while we’re probably going to stick with source-only when we do it, it’s undeniable that there will remain a temptation to simply download the binaries.

Meanwhile this has been written on a machine running Manjaro, or Arch-for-cowards as we like to call it, something that maybe confers middle-ranking bragging rights. Read a personal tale of taking off those Linux training wheels.

* Used a magnifying glass? You’re just not cutting it!