Using Your PC As A Simple Signal Generator

April 3, 2011 by Mike Nathan 29 Comments

dc_offset_circuit

[Debraj] needed a simple signal generator for a project he was working on, but didn’t have one handy. He found that the easiest and cheapest way to get clean, reliable signaling was by using something that was already sitting on his desk – his PC.

He found that the tone generator built into Audacity was quite useful, at least for generating waveforms at less than 20 KHz or so. Upon plugging his scope into his sound card’s audio jack, he observed that the PC had good frequency fidelity, though it required an additional DC offset as most cards are built to remove that offset from the waveform.

Using a LM358 as a non-inverting summing amplifier, he was able to apply a steady DC offset and generate usable signals for his micro controller projects. A schematic for his offset circuit is available on his site, should you wish to build one of your own.

[Debraj] also notes that though Audacity is a ~~cheap~~ free way to generate simple signals, any number of complex signals can be generated using MATLAB if you happen to own a copy.

Solar-powered MP3 Playing Speaker

March 31, 2011 by Mike Nathan 5 Comments

solar_speakers

[Valentin] bought a small battery-powered cube speaker with a built-in amp some time ago, but didn’t have much patience for replacing or recharging the batteries. It sat on the shelf for awhile until he decided to revive an old MP3 player he had sitting around.

He gutted a pair of solar garden lamps, retaining the solar panels, the built-in charging circuits, as well as the included rechargeable batteries. The MP3 player was disassembled, and its components were built into the speaker enclosure. The player’s buttons were relocated to the outer shell of the speaker box with a few pieces of wire, allowing him to easily control his music without having to build in a method for opening the case. Both the speaker and the MP3 player are powered by the batteries salvaged from the solar lamps, which is why he opted to mount both of the solar panels on the the side of the speaker enclosure rather than just one.

We like it even though the speaker looks a bit rough at the moment, especially where the MP3 player’s buttons were transplanted. After a few minutes of touch-up work however, it’ll look great.

If you’re interested in some more solar hacks, check out this solar-powered junkbot, these solar toys for kids, and this solar-powered WiFi repeater we featured in the past.

Headphones Use Standard-sized But Proprietary Rechargeable Batteries

March 30, 2011 by Mike Szczys 83 Comments

Here’s something we haven’t run across before. We’re familiar with proprietary battery shapes (we’re looking at you, digital camera manufacturers), or custom recharge connections (look of death directed toward cellphone manufacturers), but using electrical tricks to force AAA brand loyalty is a new one. It seems that’s exactly what is happening with [OiD’s] wireless headphones which were manufactured by Phillips.

The headphones take AAA sized batteries and can use either disposable or rechargeable varieties. There is a warning label advising that only Phillips brand rechargeables should be used, and sure enough, if you try a different brand the performance suffers both in charging time and in battery life. The original batteries are labelled as Nickel Metal Hydride at 1.2V and 550 mAh, which falls within common specs. But [OiD] noticed that there is an extra conductor in the battery compartment that makes contact with the sides of the battery case. Further inspection reveals that a reverse-biased diode makes contact through this conductor with a portion of the battery which has not been painted. This is not true with other brands, allowing the circuit to distinguish between OEM and replacements.

[OiD] shorted out that connection and immediately saw a performance boost from his replacement batteries. It’s hard to know exactly what’s going on here without a full schematic for the circuit, but we’d love to hear your speculation on this setup in the comments. Is this a low tech version of the identity chips that camera batteries sometimes hide?

Music Synthesized From The Game Of Life

March 27, 2011 by Mike Nathan 12 Comments

gameoflife_synth

[vtol] has built a very elaborate system of electronic sound machines, which can be patched together in various ways in order to create all sorts of sounds and sound effects. The modules range from simple noise synthesizers to pitch shifters, sequencers, and effects processors. The most recent addition to his synthesizer system is a matrix sequencer named 2112, which focuses on generating random sounds from a very familiar mechanism.

The sequencer simulates Conway’s Game of Life, representing the colony movements in beeps and buzzes, creating a nearly infinite array of random sound effects. Using firmware from the Game of Life board by Ladyada, the sequencer generates different sound patterns based upon the number of colonies on the board. The output varies according to the shapes and proximity of the organisms to one another. Since it is part of his already modular system, the 2112 board can be combined with any number of his other sound generators and effects machines to make all sorts of circuit bent music.

Keep reading to check out the trio of videos below demonstrating the Game of Life board in action.

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Arduino And Open Sound Control Without An Ethernet Shield

March 27, 2011 by Mike Szczys 7 Comments

Open Sound Control (OSC) is a communications protocol that can be seen as a modern alternative to MIDI. It’s specifically designed to play nicely with network communication systems. The problem with using it along with Arduino-based gadgets is that you then need to use something like an Ethernet shield to provide the network connection. [Liam Lacey] decided to use Processing as a go-between for OSC and the Arduino in lieu of the Ethernet Shield. One of the major benefits of this method is that it gives you some flexibility when it comes to how the Arduino communicates. Since a USB connected Arduino can be addressed by the Processing sketch in the same way as an AVR chip connected via an RS232 serial port, [Liam’s] method will allow you to prototype on an Arduino board, but transition to your own non-USB hardware for the finished project. The one big drawback to this method is the need to have a computer connected to your controller, but we’d bet you’d need one to run MAXmsp anyway.

SudoGlove Gets A Big Software Upgrade

March 26, 2011 by Mike Szczys 11 Comments

[Jeremy Blum] recently finished writing a couple of software packages for his SudoGlove system that turns it into a music controller with a lot of features. We’ve seen the hardware in a previous post and as a goal for this iteration he decided not to alter the hardware or the firmware controlling it whatsoever–making this a PC-side software only hack. It’s nice to see improvement on the original ideas as we feel most of the glove-based projects we’ve covered end up getting thrown in the junk box after the developer’s interest wanes.

After the break you can see and hear a demonstration of the complete system. The front end of application shown ~~was written using Processing and~~ includes a slew of user configurations for each sensor on the glove itself. Under the hood [Jeremy] built on the PureData framework in order to really unlock the potential for translating physical movement into synthesized sound. There is also a visual feedback application which will help you practice your movements, important if you’re giving live performances where each finger is a different instrument. Everything for this project, both hardware and software, has been released under a CC license so check out [Jeremy’s] site if you’re interested in building on part or all of the good work he’s done.

Update: [Jeremy] wrote in with a bit of a correction for our synopsis. The application shown in the video is written entirely in PureData and the visual debugger was written with Processing. The two are standalone packages that don’t depend on each other. He also sent us a link to download the code packages.

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WiFi Radio Plays Your Tunes In Style

March 26, 2011 by Mike Nathan 9 Comments

wifi_radio

Instructables user [Jan] likes listening to music while hacking away in his workshop, but listening to the same CDs gets tired and boring after awhile. He contemplated listening to streaming audio over the Internet, but hated the idea of needing a computer around at all times. After a bit of reading, he found some information about building a WiFi radio, and got started on constructing his own.

Using a guide he found at the MightyOhm, he hacked an Asus router to use OpenWRT, adding a music player daemon to tune in various stations. He added a small LCD display and an ATmega32 to drive it, as well as a rotary encoder to allow him to switch between stations.

The case was built using several layers of MDF which were cut using a CNC mill, and joined together with glue and wooden dowels. The front and back panels were milled out of alucobond sheets, with the remainder of the case covered in white wood veneer. The detail that went into this build is great, we especially love the “WiFi Symbol” speaker grilles.

All of his code and schematics are available for download, should you desire to make a WiFi radio of your own. Stick around to see a video of his completed radio in action.

[via MightyOhm]

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