Laugh Track Jacket Is Actually A Blazer

January 18, 2015 by 10 Comments

Picture it: your first open mic night at Larry’s Laugh Lounge. You’re up second in the lineup. It’s better than going first, but the crowd is far from hitting the two-drink minimum and your dad jokes are going over like a lead balloon. What now? Time for your secret weapon. You throw out the ‘tough crowd’ line while casually reaching into a pocket of your herringbone blazer. You press a button and the sound of crickets reaches the microphone. Someone chortles near the back. You smile, and remembering that Barbie joke from Reddit, your act takes a turn for the profane and the sweet sound of your first real laugh is forever burned in your memory.

This laugh track jacket from Adafruit’s [Becky Stern] is based on their own audio FX board, a standalone unit that can store and play WAV and OGG files. The board is also available with 16MB of flash for extended pre-recorded Foley artistry. This is an easy solder-and-sew project with a lot of wearable applications, and all of the components are available in the Adafruit store. There are plenty of places to get free sound effects that are already in WAV format, as the board does not support MP3s. As always, [Becky] has provided a clear and thorough guide with plenty of pictures and an introduction video that you can see after the break.

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Tracking Power Usage With A Raspi

January 18, 2015 by 29 Comments

With tiny, Internet-connected computers everywhere these days, home automation is finally hitting it big. [Jelora] was looking for a few more home automation projects and realized his electric meter had a pair of ‘digital information outputs’. With a Raspberry Pi and a few bits of wire, he figured out how to read this digital output and put a log of his electricity consumption up on the web.

The digital output on [Jelora]’s meter is a bit odd; it’s 1200 bps, 7 bits per character, parity, with one stop bit. It’s also a 50 kHz AC signal for a binary ‘0’ and nothing for a binary ‘1’. To read this signal, [Jelora] is using a diode to throw out half the signal, a 6N138 optoisolator so the Pi isn’t connected directly to the meter, and a small cap to smooth out the signal. Simple, and it works.

This cleaned up signal is then connected to serial to USB chip and a PHP script scrapes the data every minute. The data received from the meter is stored in a data base along with a few other bits of information: if the meter is being charged peak or off-peak rates, and the price per kWh. All this is saved on an IDE hard drive (more reliable than the SD card, surprisingly), and a ‘electricity cost per day’ is plotted on a nifty graph and served up by the Raspberry Pi.

Circuit Plotting With An HP Plotter

January 18, 2015 by 13 Comments

Over the last few years we’ve seen a few commercial products that aim to put an entire PCB fab line on a desktop. As audacious as that sounds, there were a few booths showing off just that at CES last week, with one getting a $50k check from some blog. [Connor] and [Feiran] decided to do the hacker version of a PCB printer: an old HP plotter converted to modern hardware with a web interface with a conductive ink pen.

The plotter in question is a 1983 HP HIPLOT DMP-29 that was, like all old HP gear, a masterpiece of science and engineering. These electronics were discarded (preserved may be a better word) and replaced with modern hardware. The old servo motors ran at about 1.5A each, and a standard H-Bridge chip and beefy lab power supply these motors were the only part of the original plotter that were reused. For accurate positioning, a few 10-turn pots were duct taped to the motor shafts and fed into the ATMega1284p used for controlling the whole thing.

One of the more interesting aspects of the build is the web interface. This is a small JavaScript app that is capable of drawing lines on the X and Y axes and sends the resulting coordinates from a server to the printer. It’s very cool, but not as cool as the [Connor] and [Feiran]’s end goal: using existing Gerber files to draw some traces. They’re successfully parsing Gerber files, throwing out all the superfluous commands (drills, etc), and plotting them in conductive ink.

The final iteration of hardware wasn’t exactly what [Connor] and [Feiran] had in mind, but that’s mostly an issue with the terrible conductivity of the conductive ink. They’ve tried to fix this by running the pen over each line five times, but that introduces some backlash. This is the final project for an electrical engineering class, so we’re going to say that’s alright.

Video below.

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3D Printed LED Guitar Chord Chart

January 18, 2015 by 12 Comments

Learning to play guitar can involve a lot of memorization – chords, scales, arpeggios, you name it. [MushfiqM] has made the process a bit easier with his Digital Chord Chart. Just about every beginning guitarist keeps a chord app, chord book, or even a chord poster handy. Usually these chord charts are in the form of tablature, which is a shorthand method of showing where each finger should go on the instrument. [MushfiqM] took things a step further by actually placing that chart on a 3D printed model of a guitar fretboard.

ledmatrixx[MushfiqM] started by rendering a 3D model of an abbreviated guitar using Autodesk Inventor. He then printed his creation in 3 parts: headstock, neck, and fretboard. The neck of the guitar was hollowed out to allow room for a matrix of LEDs which would show the finger positions. [MushfiqM] then painstakingly soldered in a charlieplexed matrix of 30 leds, all connected by magnet wire. The LEDs are controlled by an Arduino UNO, which has the chord and scale charts stored in flash.

For a user interface, [MushfiqM] used a 2×16 character based LCD and a low-cost IR remote control. All the user has to do is select a chord or scale, and it’s displayed on the fretboard.

There are a couple of commercial products out there which perform a similar function, most notably the Fretlight guitar. Those can get a bit pricy though – costing up to $400.00 USD for an LED enabled guitar.

[via Instructables]

Hackaday Retro Edition: Pen Computing

January 17, 2015 by 20 Comments

Although we’re well past the heyday of ‘pen computing’, and seemingly into a retro revival with laptops and tablets that come with Wacom styluses and digitizers, this doesn’t mean the pen computers of old weren’t useful. While they were mostly used for industrial applications, they were useful and some of the first practical applications of touch screen displays.

[Jason] got his hand on one of these ruggedized handheld PCs – specifically, an Itronix T5200. This three-pound mini notebook runs Windows CE Handheld PC Edition 3.01. The specs include a 74MHz RISC processor, 16 MB of RAM, 16MB of Flash, and a 7.3 inch monochrome touch screen with 640×240 resolution. It’s odd and old: when closed, it’s over two inches thick. You’ll be hard pressed to find a modern laptop that thick. [Jason]’s hardware is a pre-production version.

Unlike a lot of retro submissions that have somehow managed to pull up the Hackaday Retro Edition on old hardware, this machine actually has a browser. It’s old, it’s clunky, but it works. There are three options for getting this old computer up on the Internet – either IrDA, an RJ11 modem port, or RS232. [Jason] didn’t tell us which port he used to load up the retro edition, but he did send in a few pictures. You can check those out below.

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Handheld Linux Terminal Gets An A+

January 17, 2015 by 40 Comments

Are you all thumbs when it comes to Linux? If you follow [Chris]’s guide to building a handheld Linux terminal, that particular condition could work to your advantage. His pocket-sized machine is perfect for practicing command line-fu and honing your scripting skills on the go.

[Chris]’s creation is built around a Raspberry Pi A+ that he stripped to its essentials by removing the GPIO pins, HDMI and USB ports, the audio port, and the camera and display ports. It’s housed in a pair of plastic 2.5″ hard drive enclosures connected with a piano hinge, making it about the size of a Nintendo DS. The display is an Adafruit PiTFT touch screen and in order to save space, he soldered it directly to the Pi.

The 2.4GHz wireless thumb keyboard has all the special characters necessary for Linuxing, but the four USB ports from a dismantled hub provide flexibility. If [Chris] were to make another one, he might use this slightly larger screen from Tindie and add some charging ports to the case.

[Thanks for the tip, ar0cketman]

Arduino Reads Punch Cards

January 17, 2015 by 14 Comments

Punch cards were a standard form of program and data storage for decades, but you’d never know it by looking around today. Card punches and even readers are becoming rare and expensive. Sometimes it takes a bit of hacking [YouTube link] to get that old iron running again!

[Antiquekid3] managed to score an old punch card reader on Ebay, but didn’t have a way to interface with it. The reader turned out to be a Documation M-1000-L. After a bit of searching, [Antiquekid3] managed to find the manual [PDF link] on BitSavers. It turns out that the Documation reader used a discrete output for each row of data. One would think the Documation reader would be a perfect fit for the PDP-8 lurking in the background of [Antiquekid3’s] video, but unfortunately the ‘8 lacks the necessary OMNIBUS card to interface with a reader.

Undaunted, [Antiquekid3] threw some modern hardware into the mix, and used an Arduino Uno as a Documation to Serial interface. The Arduino had plenty of I/O to wire up with the card reader’s interface. It also had a serial interface which made outputting data a snap. The ATmega328 even had enough power to translate each card from one of IBM’s many keypunch formats to serial.

[Antiquekid3’s] test deck of cards turned out to be a floating point data set. Plotting the data with a spreadsheet results in a nice linear set of data points. Of course, no one knows what the data is supposed to mean! Want more punch card goodness? Check out this tweeting punch card reader, or this Arduino based reader which uses LEGO and a digital camera to coax the data from the paper.

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