# Acoustic Impulse Marker Tracks Sounds With A Pencil

Two students at Cornell University have put together a rather curious sound tracking device called an Acoustic Impulse Marker.

[Adam Wrobel] and [Michael Grisanti] study electrical and computer science, and for their final microcontroller class they decided to build this device using the venerable ATmega 1284p.

The system uses a three-microphone array to accurately position sharp noises within 5 degrees of accuracy. The microcontroller detects the “acoustic delay” between the microphones which allows it to identify the location of the sound’s source vector. It does this using an 8-stage analog system which converts the sounds from each microphone into a binary signal, which identifies when each microphone heard the noise. The resultant 3 binary signals are then compared for their time delay, it selects the two closest microphones, and then does a simple angle calculation based on the magnitudes of each to determine the sounds position. Continue reading “Acoustic Impulse Marker Tracks Sounds With A Pencil”

# The Effects Are IN The Guitar? It’s So Simple…

We’ve all had that problem. Up on stage, rocking out Jimi Hendrix-style on guitar with your band, but frustrated at having to mess around with foot pedals to control all of the effects. [Richard] solved this problem in a unique way: he put a preamp and a microcontroller in a guitar that can create some very interesting effects.

For the musically challenged, electric guitars often have several sets of electromagnetic pickups that detect vibrations in the strings at different points along the strings. Selecting different pickup combinations with a built-in switch changes the sound that the guitar makes. [Richard] wired the pickups in his Fender Stratocaster to the microcontroller and programmed it to switch the pickups according to various patterns. The effect is somewhat like a chorus pedal at times and it sounds very unique.

The volume and tone knobs on the guitar are used to select the programmed patterns to switch various pickups at varying speeds. This has the added bonus of keeping the stock look of the guitar in tact, unlike some other guitars we’ve seen before. The Anubis preamp, as it is called, is a very well polished project and the code and wiring schematic are available on the project site along with some audio samples.

# 120 Node Rasperry Pi Cluster For Website Testing

[alexandros] works for resin.io, a website which plans to allow users to update firmware on embedded devices with a simple git push command. The first target devices will be Raspberry Pis running node.js applications. How does one perform alpha testing while standing up such a service? Apparently by building a monster tower of 120 Raspberry Pi computers with Adafruit 2.8″ PiTFT displays. We’ve seen some big Raspberry Pi clusters before, but this one may take the cake.

The tower is made up of 5 hinged sections of plywood. Each section contains 24 Pis, two Ethernet switches and two USB hubs. The 5 sections can be run on separate networks, or as a single 120 node monster cluster. When the sections are closed in, they form a pentagon-shaped tower that reminds us of the classic Cray-1 supercomputer.

Rasberry Pi machines are low power, at least when compared to a desktop PC. A standard Raspi consumes less than 2 watts, though we’re sure the Adafruit screen adds to the consumption. Even with the screens, a single 750 watt ATX supply powers the entire system.

[alexandros] and the resin.io team still have a lot of testing to do, but they’re looking for ideas on what to do with their cluster once they’re done pushing firmware to it. Interested? Check out their Reddit thread!

# PrintBot Prints On The Ground, Uses Talcum Powder

Yes, this is a printing ‘bot but it’s not a 3D Printer. Even though it’s called Printbot, don’t get it confused with other products that may begin with ‘Print’ and end in ‘bot’. Printbot is half Roomba, half old inkjet print carriage drive and the remaining half is a small PC running Windows CE.

The whole point of this ‘bot is to draw/write/print things on the floor. No, not in ink, in talcum powder! The Roomba drives in one axis as the powder is systematically dropped in the ‘bots wake. It works one line at a time, similar to how a progressive scan TV displays an image on the screen. The PC on board the Printbot reads 8-bit gray scale images from a USB drive, re-samples the image and outputs the image one line at a time to an external microcontroller. The microcontroller is responsible for driving the Roomba forward as well as moving the hopper’s position and dispensing the powder in the correct place. Check out the small photo below. That black and white strip is not there for good looks. It is part of the encoder positioning system that is responsible for communicating the location of the hopper back to the microcontroller.

# Retrotechtacular: The Future’s So Bright, We’re Gonna Need Photochromic Windowpanes

This is a day in the life of the Shaw family in the summer of 1999 as the Philco-Ford Corporation imagined it from the space-age optimism of 1967. It begins with Karen Shaw and her son, James. They’re at the beach, building a sand castle model of their modular, hexagonal house and discussing life. Ominous music plays as they return in flowing caftans to their car, a Ford Seatte-ite XXI with its doors carelessly left open. You might recognize Karen as Marj Dusay, who would later beam aboard the USS Enterprise and remove Spock’s brain.

The father, Mike Shaw, is an astrophysicist working to colonize Mars and to breed giant, hardy peaches in his spare time. He’s played by iconic American game show host Wink Martindale. Oddly enough, Wink’s first gig was hosting a Memphis-based children’s show called Mars Patrol. He went on to fame with classics such as Tic Tac Dough, Card Sharks, Password Plus, and Trivial Pursuit.

Mike calls up some pictures of the parent trees he’s using on a screen that’s connected to the family computer. While many of today’s families have such a device, this beast is almost sentient. We learn throughout the film that it micromanages the family within an inch of their lives by keeping tabs on their physiology, activities, financial matters, and in James’ case, education.

# Hackaday 10th Anniversary: Non-Binary Computing

When [Thundersqueak] was looking for a project for The Hackaday Prize, she knew it needed to be a special project. IoT devices and microcontrollers are one thing, but it’s not really something that will set you of from the pack. No, her project needed to be exceptional, and she turned to logic and balanced ternary computing.

[Thundersqueak] was inspired to design her ternary computer from a few very interesting and nearly unknown historical computing devices. The first was the [Thomas Fowler] machine, designed all the way back in 1838. It could count to several thousand using a balanced ternary mechanical mechanism. The [Fowler] machine was used to calculate logs, and the usual boring mathematical tasks of the time.

A bit more research turned up the Setun, an electronic computer constructed out of vacuum tubes in 1958. This computer could count up to 387,000,000 with eighteen ternary digits. On the binary machine you’re using right now, representing that would take twenty-nine binary digits. It’s about a 2.5 times more efficient way of constructing a computer, and when you’re looking for the right vacuum tubes in 1950s USSR, that’s a great idea.

[Thundersqueak] isn’t dealing with vacuum tubes – she has a world of semiconductors at her fingertips. After constructing a few truth tables for ternary logic, she began designing circuits to satisfy the requirements of what this computer should do. The design uses split rails – a negative voltage, a positive voltage, and ground, with the first prototype power supply made from a 741 Op-amp. From there, it was just breadboarding stuff and checking her gates, transistors, and truth tables to begin creating her ternary computer.

With the basic building blocks of a ternary computer done, [Thundersqueak] then started to design a basic ALU. Starting with a half adder, the design then expanded to a full adder with ripple carry. We’re sure there are plans for multiplying, rotating, and everything else that would turn this project into a CPU.

# Internet-Connected TI-84

Just before the days where every high school student had a cell phone, everyone in class had a TI graphing calculator. In some ways this was better than a cell phone: If you wanted to play BlockDude instead of doing trig identities, this was much more discrete. The only downside is that the TI calculators can’t easily communicate to each other like cell phones can. [Christopher] has solved this problem with his latest project which provides Wi-Fi functionality to a TI graphing calculator, and has much greater aspirations than helping teenagers waste time in pre-calculus classes.

The boards are based around a Spark Core Wi-Fi development board which is (appropriately) built around a TI CC3000 chip and a STM32F103 microcontroller. The goal of the project is to connect the calculators directly to the Global CALCnet network without needing a separate computer as a go-between. These boards made it easy to get the original Arduino-based code modified and running on the new hardware.

After a TI-BASIC program is loaded on the graphing calculator, it is able to input the credentials for the LAN and access the internet where all kinds of great calculator resources are available through the Global CALCnet. This is a great project to make the math workhorse of the classroom even more useful to students. Or, if you’re bored with trig identities again, you can also run a port of DOOM.