Open Source Hardware
Open Source Hardware is hardware that keeps its designs available in a way similar to the open source in software.
Open Source Hardware is used as an alternative to the related and perhaps broader term of Open Hardware. It is in the process of being replaced more and more by the successor movement, i.e. Open Design.
Typology
Developed by Make magazine at http://www.makezine.com/blog/archive/2007/04/open_source_hardware_what.html
The original article has many examples with diagrams.
Electronic hardware can be divided up into layers, each of which has different document types and licensing concerns. Each level can be open sourced, but the exact nature of what it means to open it varies. In practice, not every layer is fully open. Often only a subset of the layers are released, documented or open source.
1/ Hardware (Mechanical) diagrams
Dimensions for enclosures, mechanical subsystems, etc. For 2d models, preferred document type is vector graphics file, with dimension prints, DXF or AI, etc.
2/ Schematics & Circuit diagrams
Symbolic diagrams of electronic circuitry, includes parts list (sometimes inclusively). Often paired with matching layout diagram. Preferred document type is any sort of image (PDF, BMP, GIF, PNG, etc)
3/ Parts list
What parts are used, where to get them, part numbers, etc.
4/ Layout diagrams
Diagrams of the physical layout of electronic circuitry including the placement of parts, the PCB copper prints and a drill file. This is often paired with a schematic. Preferred distribution is Gerber RS274x and Excellon (for drills). These are like PostScript for printers but the primitives aren't text and arcs, they're lines of solder and components.
5/ Core/Firmware
The source code for that runs on a microcontroller/microprocessor chip. In some cases, the code may be the design of the chip hardware itself (in VHDL). Preferred distribution: text file with source code in it, as well as compiled 'binary' for the chip.
6/ Software/API
The source code that communicates or is used with the electronics from a computer.
Examples
Here are a few examples (some previously noted) of projects that are close to "pure" open source hardware projects:
Compiled by Makezine at http://www.makezine.com/blog/archive/2007/04/open_source_hardware_what.html
Arduino - physical computing platform at http://www.arduino.cc/
Chumby - information device at http://www.chumby.com/
Daisy MP3 player - An open source MP3 player, at http://www.makezine.com/daisy/
RepRap / Fab@Home - Open source 3D printer, at http://www.reprap.org/bin/view/Main/WebHome
OpenEEG - an EEG design that is OS & available as a kit, at http://openeeg.sourceforge.net/doc/
x0xb0x - Roland 303 clone MIDI synth at, http://www.ladyada.net/make/x0xb0x/
See also:
More Information
A business model for open source hardware, at http://pages.nyu.edu/~gmp216/papers/bmfosh-1.0.html
See related items on Open Hardware, Open Design, Open Cores
See the info on the Open Hardware Licence