With modern voice assistants we can tell a computer to play our favorite music, check the weather, or turn on a light. Like many of us, [nerdaxic] gave in to the convenience and perceived simplicity of various home automation products made by Google and Amazon. Also like many of us, he found it a bit difficult to accept the privacy implications that surround such cloud connected devices. But after selling his Home and Echo, [nerdaxic] missed the ability to control his smart home by voice command. Instead of giving in and buying back into the closed ecosystems he’d left behind, [nerdaxic] decided to open his home to a murderous, passive aggressive, sarcastic, slightly insane AI: GLaDOS, which you can see in action after the break.
Using open source designs from fellow YouTube creator [Mr. Volt], [nerdaxic] 3d printed as much of the GLaDOS animatronic model as he was able to, and implemented much of the same hardware to make it work. [nerdaxic] put more Open Source Software to use and has created a functional but somewhat limited home AI that can manage his home automation, give the weather, and tell jokes among other things. GLaDOS doesn’t fail to deliver some great one liners inspired by the original Portal games while heeding [nerdaxic]’s commands, either.
A ReSpeaker from Seeed Studio cleans up the audio sent to a Raspberry Pi 4, and allows for future expansion that will allow GLaDOS to look in the direction of the person speaking to it. With its IR capable camera, another enhancement will allow GlaDOS to stare at people as they walk around. That’s not creepy at all, right? [nerdaxic] also plans to bring speech-to-text processing in-house instead of the Google Cloud Speech-To-Text API used in its current iteration, and he’s made everything available on GitHub so that you too can have a villainous AI hanging on your every word.
Some of you around the world may have come across these Android-based gaming tables installed in your local fast-food outlet, and may even have been lucky enough to paw at one that was actually working at the time.
Originally based on an ancient mini PC, with a 1080p flat panel LCD and a touch overlay, they would have been mind-blowing for small children back in the day, but nowadays we expect somewhat more. YouTuber [BigRig Creates] got his hands on one, in a less than pleasant condition, but after a lot of soap and water, it was stripped down and the original controller junked in favour of a modern mini PC. To be clear, there isn’t much left beyond the casing and display from the original hardware, but we don’t care, as a lot of attention was paid to the software side of things to get it to triple-booting into Windows 10, Android x86 and Linux running emulation station, covering all those table-gaming urges you may have.
Internally, there is a fair amount of room for improvement on the wiring side of things, and [BigRig] is quick to admit that, but that’s what this learning game is all about. Now, many of you will choke on the very idea of playing games on a table system like this, after all, it’s pretty obvious this will be really hard on the back and neck. But, it does offer the easy option to switch from landscape to portrait orientation, simply by walking around the side, so it does have an upside. Also you’ve got a handy place to dump your beer and the takeaway when it arrives, so maybe not such a bad thing to have in your apartment? And, yes, it does run Doom.
We were particularly amused by the custom boot logo as well as the slick custom art in emulation station. It’s attention to detail like this that makes a build a great one and a conversation piece at parties. Now if only he could sort out that wiring job.
If you’ve got a collection of classic game consoles, finding the space to set them all up can be a challenge. But the bigger problem is figuring out how to hook them all up to a TV that, at best, might only have two or three inputs. [odelot] recently wrote in to tell us how he solved both problems with his voice-controlled wall of gaming history.
To mount the systems to the wall, [odelot] designed and printed angled brackets that attach to specially shaped pieces of 3 mm MDF. They do a pretty good job of holding the systems at a visually interesting angle while making themselves scarce, with only the notoriously slick-bottomed Wii needing some extra clips on the front to keep it from sliding off. He also printed up a series of blocks and pipes, no doubt a reference to Mario Bros., to hold the power and video cables for each system.
As to connecting them all up to his TV, [odelot] picked up an eight-device Extron VGA switch that features a serial port for remote control. After getting all the systems adapted over to the appropriate video standard, he then wired an ESP8266 to the switch and wrote some code that ties it into Amazon’s Alexa voice assistant.
By just saying the name of the system he wants to play, the microcontroller will flick the switch over to the appropriate input and turn on a ring of blue LEDs under the appropriate shelf to signify which console has been selected. There’s even an array of solid state relays that will eventually control the mains power going to each system, though [odelot] hasn’t fully implemented it yet. Currently the electronics for this project live on a fairly packed breadboard, but it looks like he’s in the early stages of designing a proper PCB to clean it all up.
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
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”→
Back in 2018 we covered a project that would break a video down into its individual frames and slowly cycle through them on an e-paper screen. With a new image pushed out every three minutes or so, it would take thousands of hours to “watch” a feature length film. Of course, that was never the point. The idea was to turn your favorite movie into an artistic conversation piece; a constantly evolving portrait you could hang on the wall.
[Manuel Tosone] was recently inspired to build his own version of this concept, and now thanks to several years of e-paper development, he was even able to do it in color. Ever the perfectionist, he decided to drive the seven-color 5.65 inch Waveshare panel with a custom STM32 board that he estimates can wring nearly 300 days of runtime out of six standard AA batteries, and wrap everything up in a very professional looking 3D printed enclosure. The end result is a one-of-a-kind Video Frame that any hacker would be proud to display on their mantle.
The Hackaday.IO page for this project contains a meticulously curated collection of information, covering everything from the ffmpeg commands used to process the video file into a directory full of cropped and enhanced images, to flash memory lifetime estimates and energy consumption analyses. If you’ve ever considered setting up an e-paper display that needs to run for long stretches of time, regardless of what’s actually being shown on the screen, there’s an excellent chance that you’ll find some useful nuggets in the fantastic documentation [Manuel] has provided.
We always love to hear about people being inspired by a project they saw on Hackaday, especially when we get to bring things full circle and feature their own take on the idea. Who knows, perhaps the next version of the e-paper video frame to grace these pages will be your own.
As we’ve traced our no-nonsense path through the world of Hi-Fi audio, we’ve started with the listener, understood the limitations of the human ear, and thence proceeded to the loudspeaker. We’ve learned a bit about speaker cabinets and their design, so it’s time to venture further down the chain to the amplifier that drives those speakers.
The sharp-eyed will be ready to point out that along this path also lies the speaker cables, but since we’ll be looking at interconnects at a later date we’ll be making the dubious and simplistic assumption for now that the wires between speaker and amplifier are ideal conductors that don’t have a bearing on listening quality. We’ll be looking at amplifiers in enough detail to warrant more than one piece on the subject, so today we’ll start by considering in a slightly abstract way what an amplifier does and where it can fall short in its task. We’ll be introducing probably the most important thing to consider in any audio system, namely distortion.
The job of an audio amplifier is to take an audio signal at its input and present the same signal on its output at a greater amplitude. In the case of a preamplifier it will usually be designed to work with high impedances in the order of 50 kΩ at both input and output, while in a power amplifier designed to drive speakers or headphones it will drive a much lower impedance. Commonly this will be 4 Ω or 8 Ω for loudspeakers, and 32 Ω for headphones. Continue reading “Know Audio: Amplifiers And Distortion”→
As we’ve started out on our journey through the world of Hi-Fi audio from a strictly practical and engineering viewpoint without being misled by any audiophile woo, we’ve already taken a look at the most important component in any audio system: the listener’s ear. It’s time to move down the chain to the next link; the loudspeaker.
Sound is pressure waves in the air, and the purpose of a loudspeaker is to move the air to create those waves. There are a variety of “exotic” loudspeaker technologies including piezoelectric and electrostatic designs, here we’ll be considering the garden variety moving-coil speaker. It’s most usually used for the large bass or smaller mid-range drivers in a typical speaker system. Continue reading “Know Audio: A Loudspeaker Primer”→