Building A Custom Linux Single Board Computer Just To Play Spotify

September 22, 2021 by Lewin Day 31 Comments

If you want to hook up an existing stereo or amplifier to Spotify, there’s a fair few options on the market. You can even just order a Raspberry Pi and be done with it. [Evan Hailey] went his own way, however, and built his own Spotify Box from scratch.

[Evan] even made this tidy wooden enclosure, learning yet more along the way!

Housed inside a tidy little wooden enclosure of his own creation, the Spotify Box can turn any amplifier into a remote-controlled Spotify player via Spotify Connect. Pick the songs on your smartphone, and they’ll play from the Spotify Box as simple as that.

The project is based on the Allwinner V3S, a system-on-chip with a 1.2GHz ARM-Cortex-A7 core, 64MB of DDR2 RAM, and an Ethernet transceiver for good measure. There’s also a high-quality audio codec built in, making it perfect for this application. It’s thrown onto a four-layer PCB of [Evan’s] own design, and paired with a Wi-Fi and BlueTooth transceiver, RJ-45 and RCA jacks, a push-button and some LEDs. There’s also an SD card for storage.

With a custom Linux install brewed up using Buildroot, [Evan] was able to get a barebones system running Spotifyd while communicating with the network. With that done, it was as simple as hooking up the Spotify Box to an amp and grooving out to some tunes.

Along the way, [Evan] learned all about compiling drivers and working with embedded Linux, as well as how to take a bare SoC and build it into a fully-functional single-board computer. When someone else says they “made” a Spotify player, he presumably gets to clear his throat.

If you fancy retro computers, consider interfacing Spotify with your classic Mac instead!

[Thanks to Jay Carlson for the tip!]

A man watching money being shredded in a picture frame

Banksy-Like Stock Tracker Shreds Your Money When The Market’s Down

September 20, 2021 by Robin Kearey 14 Comments

For anyone playing the stock market, and perhaps even more so for those investing in cryptocurrencies, watching the value of your portfolio go up and down can be a stressful experience. If you’d like to have a real-time display of your investments that adds even more stress, [Luis Marx] has got you covered. His latest project is a plexiglass case (video in German) that fills up with banknotes when your portfolio is up, and shreds those same notes when it’s down.

Inspired by an infamous Banksy artwork, [Luis] began by building a wood-and-plexiglass display case suitable for hanging on the wall in his office. He then installed a small paper shredder, modified with a servo so that it could be operated by an Arduino. Unable to find an off-the-shelf banknote dispenser, he designed and 3D-printed one, consisting of a spring-loaded tray and a motor-driven wheel.

The project also includes a Raspberry Pi, programmed to fetch market data from online sources and calculate the net profit or loss of [Luis]’s portfolio. The resulting system is a rather disturbing visualization of the ups and downs of the market: having to sweep strips of green paper off your floor adds insult to the pain of losing money.

If you want a less painful way to keep track of your investments, try this Rocketship. For those interested in traditional stock tickers, this ESP32 based one might be more to your liking.

Continue reading “Banksy-Like Stock Tracker Shreds Your Money When The Market’s Down” →

Lego Submarine Gets Balloon Ballast System

September 19, 2021 by Lewin Day 21 Comments

Lego is a fun building block which vast numbers of the world’s children play with every day. However, the mechanical Technic line of Lego building blocks has long offered greater options to the budding engineer. [Brick Experiment Channel] is one such soul, working hard on their latest Lego submarine.

The sub is built inside of a glass food container, chosen for its removable plastic lid with a watertight seal. This keeps all the mechanics dry, as well as the custom electronics built to allow a 27MHz RC controller to send signals to the Lego electronics. This is key as higher frequency radios such as Bluetooth or WiFi can’t penetrate water nearly as well.

A magnetic coupling fitted to a Lego motor is used to drive the propeller in the water without the leaks common when trying to seal a rotating shaft. A second coupling on a Lego servo along with a creative steering arrangement allows the propeller to be turned to steer the craft.

The ballast system is simple. A balloon is filled by a Lego motor running an air pump, capable of 3.0 mL a second and capable of creating a maximum pressure of 2.0 bar. When the balloon is inflated, the buoyancy goes up and the sub rises. Run the motor the other way and the balloon is emptied by a clever clutch and valve arrangement, reducing buoyancy and causing the sub to sink.

The sub isn’t perfect. Maintaining a set depth underwater can be difficult with the rudimentary ballast system, perhaps as the balloon changes shape with varying water pressure. Sometimes, Lego axles slip out of their gears, too, and the radio only works for a few meters under water.

However, simply building a Lego sub of any sort is a remarkable feat. It’s interesting to see the variances in the design compared to earlier projects from [Brick Experiment Channel], too, as we’ve featured their earlier subs before. Video after the break.

Continue reading “Lego Submarine Gets Balloon Ballast System” →

Banish Early Morning Zombification With The Zom-b-gone!

September 17, 2021 by Dave Rowntree 5 Comments

[Applied Procrastination] aka [Simen E. Sørensen] has a simple project to help those of us that struggle with early-morning zombification. By leveraging the backlight optics from a broken LCD monitor, it is possible to create an excellent diffused light source to simulate daylight, before your chosen waking time. The theory is that it is less shocking to the brain to be woken more gradually than an alarm may do. The increasing light level is to prepare the brain with a slowly increasing light level, reminiscent of daybreak, before being properly awoken by an alarm, regardless of the actual light level outdoors. This particularly useful for those of us in more northern regions, such as [Simen]’s native Norway, where mornings are very dark in the winter months.

Daylight is not purely a diffuse source however, it depends on the degree of atmospheric scattering, local reflections and such, but as far as we’re concerned here, we can just aim for as diffuse a light source a possible.

The implementation makes use of the existing LCD metal frame, the light guide panel (usually a big hunk of acrylic covered in etched markings on one side) the diffuser/brightener sheet, and the prism sheet. A white LED strip mounted around the frame edge directs light into the light guide, which with a combination of total internal reflection and scattering on one side only, effectively turns the light through 90 degrees, and spreads it out evenly across that surface. The result of this optical sandwich is flat, even light, exactly what you want for a display, and also for simulating daylight.

Nestled beneath the expected 3D printed frame, is a custom PCB derived by smooshing together the designs from the Adafruit DS3231 RTC module and the Arduino Nano, an additional push button and rotary encoder complete the minimalistic UI, and allow the device to double up as general purpose lamp during the day. Despite a few wobbles with assembling the frame, and some incorrect PCB footprinting, the whole thing came together pretty nicely. This is a perfect thing to do with broken LCD monitors, eeking out a new life and keeping the amount of landfill to a minimum.

For further details of the hardware and codes, see the Zom-b-Gone Github.

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Putting An Afterburner On An Electric Ducted Fan

September 17, 2021 by Lewin Day 30 Comments

Afterburners are commonly agreed to be the coolest feature of military fighter aircraft. Injecting raw fuel into the exhaust stream of a jet engine, afterburners are responsible for that red-hot flaming exhaust and the key to many aircraft achieving supersonic flight. [Integza] wanted to see if the same concept could be applied to an electric ducted fan, and set out to find out.

Of course, building an afterburner for an EDF does add a lot of complication. A flame tube was installed downstream of the EDF, fitted with a brass tube drilled carefully to act as a fuel injector. The flame tube was also fitted with an automotive glow plug in order to ignite the fuel, which was lighter refill gas straight from a can. The whole assembly is wrapped up inside a clear acrylic tube that allows one to easily see what’s happening inside with the combustion.

Results were mixed. While the fuel did combust, but in a rather intermittent fashion. In proper operation, an afterburner would run with smooth, continuous, roaring combustion. Additionally, no thrust measurements were taken and the assembly barely shook the desk.

Thus, if anything, the video serves more as a guide of how to burn a lot of lighter gas with the help of an electric fan. The concept does has merit, and we’ve seen past attempts, too, but we’d love to see a proper set up with thrust readings with and without the afterburner to see that it’s actually creating some useful thrust. Video after the break. Continue reading “Putting An Afterburner On An Electric Ducted Fan” →

Taking A Deep Dive Into SPI

September 16, 2021 by Jim Heaney 9 Comments

With the prevalence of libraries, it has never been easier to communicate with hundreds of different sensors, displays, and submodules. But what is really happening when you type SPI.begin() into the Arduino IDE? In his most recent video, [Ben Eater] explores the Serial Peripheral Interface (SPI) and how it really works.

Most Hackaday readers probably know [Ben] from his breadboard-based computers, such as the 6502 build we featured in 2019. Since then he has been hard at work, adding new and interesting additions to his breadboard computer, as well as diving into different communication protocols to better understand and implement them. For this video, [Ben] set the goal of connecting the BME280, a common pressure, temperature, and humidity sensor with an SPI interface, to his breadboard 6502 computer. Along the way, [Ben] discusses how exactly SPI works, and why there is so much conflicting nomenclature and operations when looking at different SPI devices.

If breadboard computers aren’t your thing, there are tons of other uses for the BME280, such as helping to modernize a Casio F-91W.

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Making A Car Key From A Ratcheting Wrench

September 12, 2021 by Lewin Day 45 Comments

Car keys these days are remarkably complex beasts. Covered in buttons and loaded with security transponders, they often cost hundreds of dollars to replace if you’re unlucky enough to lose them. However, back in the day, keys used to just be keys — a hunk of metal in a mechanical pattern to move some levers and open a door. Thus, you could reshape a wrench into a key for an old car if that was something you really wanted to do.

The concept is simple. Take a 12mm ratcheting wrench, and shape the flat section into a profile matching that of a key for an older car without any electronic security features. The first step is to cut down the shaft, before grinding it down to match the thickness and width of the original key.

The profile of the key is then drawn onto the surface, and a Dremel used with a cutting disc to create the requisite shape. Finally, calipers are used to mark out the channels to allow the key to slide into the keyway, before these are also machined with the rotary tool.

Filing and polishing cleans up the final result to create a shiny, attractive ratchet wrench key. Even better, it does a great job of opening the car, too.

Similar machining techniques can be used to duplicate a key from just a photo (something I did back in 2019 to prank my friend). Alternatively, 3D printing can be great for reproducing even high-security keys. Video after the break.

Continue reading “Making A Car Key From A Ratcheting Wrench” →