Know Audio: Amplifier Nuts And Bolts

August 24, 2021 by Jenny List 31 Comments

As we’ve followed a trail through Hi-Fi and audio systems from the listener’s ear towards the music source, we’ve reached the amplifier. In our previous article we gave a first introduction to distortion and how some amplifier characteristics can influence it, and here we’ll continue along that path and look at the amplifier itself. What types of audio amplifier circuits will you encounter, and what are their relative merits and disadvantages?

A Few Amplifier Basics

Horowitz and Hill's Transistor Man — Horowitz and Hill’s Transistor Man

If you know anything about a transistor, it’s probably that it’s a three terminal device whose output pin forms part of a potential divider whose state is dependent on what is presented to its input pin. The Art of Electronics had it as a cartoon of a man standing inside a bipolar transistor and adjusting a variable resistor between collector and emitter while watching an ammeter on the base.

Properly biased in its conducting range, a transistor can behave as a linear device, in which the potential divider voltage moves in response to the input in a linear relationship, and thus the voltage on the output is an amplified version of the voltage on the output. This is the simplest of transistor amplifiers, and because different types of amplifier are referred to by lettered classes, it’s known as a class A amplifier. Continue reading “Know Audio: Amplifier Nuts And Bolts” →

Game Boy Advance SP Case Mod Adds Battery Capacity And Modern Interfaces

August 24, 2021 by Robin Kearey 5 Comments

While there’s nothing quite like running retro games on their original hardware, using older consoles in today’s day and age can be a hassle due to incompatibilities with modern chargers and headphones. [tito] and [kyle] worked together to update Nintendo’s Game Boy Advance SP with a whole bunch of new features, tightly packed inside a 3D-printed replacement backshell. (Video, embedded below.)

The original 600 mAh battery has been replaced with a 1600 mAh pack for several hours of additional screen time. A Qi standard wireless power module as well as a USB-C connector allows charging the battery without carrying the original mains adapter. A Bluetooth module enables the use of wireless headphones, and a 3.5 mm jack enables classic earbuds as well, a feature lost when the SP replaced the original GBA.

The new backshell fits exactly on the original console, making it about 10 mm thicker. Although this makes it slightly less portable, it is apparently more comfortable to hold for those with big hands. The new functionality is implemented using off-the-shelf circuit boards, connected together with flying wires that are soldered to the required points on the GBA’s circuit board. The original connectors and switches remain in place and functional, and the entire operation can be undone if you want to return the device to its original state.

Others have added USB charging to the original GBA, or even stretched that handheld to become twice as wide. But adding significant new functionality previously required replacing the handheld’s entire contents.

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As ISS Enters Its Final Years, Politics Take Center Stage

August 24, 2021 by Tom Nardi 40 Comments

There was a time when the idea of an international space station would have been seen as little more than fantasy. After all, the human spaceflight programs of the United States and the Soviet Union were started largely as a Cold War race to see which country would be the first to weaponize low Earth orbit and secure what military strategists believed would be the ultimate high ground. Those early rockets, not so far removed from intercontinental ballistic missiles (ICBMs), were fueled as much by competition as they were kerosene and liquid oxygen.

Space Shuttle docked to Mir space station in 1995. — *Atlantis* docked to *Mir* in 1995.

Luckily, cooler heads prevailed. The Soviet Almaz space stations might have carried a 23 mm cannon adapted from tail-gun of the Tu-22 bomber to ward off any American vehicles that got too close, but the weapon was never fired in anger. Eventually, the two countries even saw the advantage of working together. In 1975, a joint mission saw the final Apollo capsule dock with a Soyuz by way of a special adapter designed to make up for the dissimilar docking hardware used on the two spacecraft.

Relations further improved following the dissolution of the Soviet Union in 1991, with America’s Space Shuttle making nine trips to the Russian Mir space station between 1995 and 1997. A new era of cooperation had begun between the world’s preeminent space-fairing countries, and with the engineering lessons learned during the Shuttle-Mir program, engineers from both space agencies began laying the groundwork for what would eventually become the International Space Station.

Unfortunately after more than twenty years of continuous US and Russian occupation of the ISS, it seems like the cracks are finally starting to form in this tentative scientific alliance. With accusations flying over who should take the blame for a series of serious mishaps aboard the orbiting laboratory, the outlook for future international collaboration in Earth orbit and beyond hasn’t been this poor since the height of the Cold War.

Continue reading “As ISS Enters Its Final Years, Politics Take Center Stage” →

How Do You Make A Raspberry Pi On A Stick?

August 24, 2021 by Michael Shaub 38 Comments

We agree with [magic-blue-smoke] that one of the only things more fun than a standard Raspberry Pi 4 is the Compute Module form factor. If they are not destined to be embedded in a system, these need a breakout board to be useful. Each can be customized with a myriad board shapes and ports, and that’s where the real fun starts. We’ve already seen projects that include custom carrier boards in everything from a 3D Printer to a NAS and one that shows we can build a single-sided board at home complete with high-speed ports.

[magic blue smoke] used this ability to customize the breakout board as an opportunity to create a hackable media player “stick” with the Raspberry Pi built-in. We love that this Raspberry Pi CM4 TV Stick eliminates all the adapters and cables usually required to connect a Pi’s fiddly micro HDMI ports to a display and has heat sinks and an IR receiver to boot. Like a consumer media player HDMI stick, all you need to add is power. Continue reading “How Do You Make A Raspberry Pi On A Stick?” →

Wood And Glue Scale Kayak Is Super

August 24, 2021 by Michael Shaub 7 Comments

While we don’t feature many woodworking projects here, we always love learning from people who really know their stuff in any medium. [Brian Oltrogge] showed us a hands-off way to shape aluminum with this 3D print sand-casting project and now brings us a very hands-on kayak project.

We have seen kayaks made from plastic wrap and 3D printed parts, and in the video after the break, [Brian Oltrogge] is building a scale model to validate a wood kayak design created with Rhino 3D and Grasshopper. Besides being a joy to watch the craft of the project, the video is full of great hacks. The “buck” that the wood is formed over sits on CNC cut stands that slot into it. The thickness of three layers of laminated veneer fits the 1:4 scale model perfectly representing 3/4” plywood, and the laser-cut parts use the exact pattern that the final full-size CNC will.

There are also some great tool hacks hidden in the video. [Brian Oltrogge] tells us about a spiral scroll saw blade that can cut in any direction, but as a bonus tip, we also can see a clamp compressing the saw while the blade is tensioned. Watch the video through the end to see some clever wall-mounting brackets too.

The video doesn’t tell us what a Stitch & Glue boat is or how the full-scale will be assembled. To find out more about that, see this charmingly odd vintage film from Chesapeake Light Craft.

Thanks for the tip [Keith Olson]

Wooden Monowheel Build Is Simplicity Itself

August 23, 2021 by Dave Rowntree 9 Comments

Monowheels are nothing new, first being patented in the middle of the 19th century, but never really went mainstream due to, well, quite a lot of obvious issues. We’ve got problems with forward visibility, stability, steering, especially at speed, and the hilariously-named ‘gerbiling’ where the rider can spin around inside the wheel akin to a gerbil in a wheel. Fun times! But obviously that didn’t stop [The Q] from adding to the monowheel corpus by building one out of wood.

Sometimes people take on these projects simply for a laugh, like this bright orange one we covered a while back. Sometimes they’re powered by a motor, be it electric or internal combustion. Some are hand-cranked, some are pedal-powered, its all been tried.

[The Q] is no stranger to interesting wooden builds, and this video from a year ago shows him building a very simple direct-pedal-drive monowheel. The vast majority of the structure is wood, glued and screwed the old-fashioned way, with a bit of metalwork where necessary. We particularly like the simple counterweight solution which doubles up as a parking brake. It may look a little ungainly, but we can’t think of a simpler solution that would make much sense.

The build video after the break is six and half minutes of well executed videography for your viewing pleasure.

Continue reading “Wooden Monowheel Build Is Simplicity Itself” →

ESP8266 weather widget with touchscreen display

Nothing Should Cloud The Build Of This Wieldy Weather Widget

August 23, 2021 by Kristina Panos 9 Comments

Weather is one of those things that seems to be endlessly interesting to hackers. We may decry the notion that weather can be accurately predicted two days out, much less seven, but if there’s an extended forecast available, by gosh we’re gonna take a gander at it.

So why pick up your phone or open a browser tab every time you want to check the temperature? If you’re so into it, you should build a desktop weather widget. [opengreenenergy] has written a great guide to a tidy build of this classic and oh-so-useful project that covers everything from the soldering to obtaining an API key. Inside is an ESP8266 and a 2.8″ touch screen display that shows localized conditions via Open Weather Map. The main screen shows the time, date, current weather, 7-day forecast, and the moon phase for each day, and subsequent screens go into further detail. It’s informative without being busy.

We love the streamlined look of the snap-fit enclosure. This may be a fairly simple project, but the build as designed is challenging due to the space constraints inside. Check out the video after the break, which features the venerable Stickvise.

What? You’ve never heard of the Stickvise? You must be new around here. Allow me to introduce you two.

Continue reading “Nothing Should Cloud The Build Of This Wieldy Weather Widget” →