LibreCAD is a free, open source, slim, cross-platform and multi-language 2D CAD application developed by R. van Twisk.

Features

• Open and edit dxf and cxf files.
• Zoom in / zoom out with mouse wheel.
• Draw elements such as Points, 2 Points, Angle, Horizontal line,Vertical line, Rectangle, Parallel line, Parallel through point, Bisector, Tangent( P,C ), Tangent( C,C ), Orthogonal, Relative angle, Freehand Line, Polygon( Cen, Cor ), Polyline, Spline, Ellipse, Circle, Concentric Circles, Arc, Text, Hatch, Image, etc.
• Perform modifications such as Move, Copy, Rotate, Scale, Mirror, Trim, Lengthen, Bevel, Round, Divide, Stretch, Properties, Attributes, Delete, Delete selected, Explode Text into Letters, Explode, etc.
• Add, Edit, Toggle, Remove, Freeze, Defreeze layers.
• Add, Edit, Insert, Create, Rename, Remove, Explode, Freeze, Defreeze blocks.
• Multiple units available: Inch, Foot, Mile, Millimeter, Centimeter, Meter, Kilometer, Microinch, Mil, Yard, Angstrom, Nanometer, Micron, Decimeter, Decameter, Hectometer, Gigameter, Astro, Lightyear, Parsec.
• Export to bmp, png, ppm, xbm, xpm files.
• Multi-Language UI: English, French, German, Italian, Spanish, Greek, Czech, Danish, Polish, Russian, etc.
• Plus many more.

LibreCAD works on Windows 7, Windows XP, Mac OS X, etc.

LibreCAD is a 10.2MB download available from SourceForge.net.

Alternatively, you may also be interested in DraftSight as well as A9CAD.

A9CAD is a free, lightweight, multiple-document interface and simple two-dimensional computer-aided design and drafting utility for Windows developed and released by A9Tech.

Features

• Easy to get started, no learning curve.
• Open, edit and save to DWG, DXF files( up to DWG/DXF 2000 ), you can convert the DWG files saved by Autocad 2010 to the old version with A9Convert, then open it with A9CAD.
• Draw elements like Point, Line, Rectangle, Arc, Circle, Ellipse, PolyLine, Text, Image, Dimension( Align, Vertical, Horizontal, Angular, Diameter, Radial ).
• Perform modifications such as Select, Deselect, Erase, Copy, Move, Scale, Rotate, Explode, Trim, Extend, Fillet, Offset, Break, Mirror, Join.
• Change the properties( color, dim style, linetype, lineweight, pen width, etc. ) of selected entry.
• Layer Manager, Dim Style Editor, Text Style Editor.
• Zoom in or out with Ctrl + mouse wheel.
• Pan with middle mouse button.
• Print and print preview.
• Export to emf files.

A9CAD works on Windows 7, Windows XP, Windows Vista and Windows 2000.

A9CAD is a 15.5MB download available from CNET and the developer’s website.

DraftSight is a free, cross-platform, professional level design, drafting, engineering and architectural sketching application that allows to create, open, save, edit and view DWG, DXF, DWT files, you can use it as an alternative to Autodesk AutoCAD.

Features

• Zoom in or out with Ctrl + mouse wheel.
• Pan with middle mouse button.
• Draw Line, Infinite Line, Rich Line, Ray, 3D PolyLine, PolyLine, Polygon, Rectangle, Sketch, Arc, Circle, Ring, Spline, Ellipse, Point, Block, Table, Bound Area, Hatch/Fill, Region, Mask, Text, Shape, Mesh( 2D Solid ), 3D Face, 3D Mesh, Tabulated, Edge, Ruled, Revolved ).
• Create, show, hide, freeze, lock, unlock, isolate, unisolate, activate, delete, thaw layers.
• Modify selected entries, the available tools include: copy, delete, mirror, move, offset, pattern, rotate, scale, stretch, chamfer, fillet, split at point, split, weld, extend, trim, edit hatch, display order, edit polyline, explode.
• Mouse gestures.
• Highly customizable.
• Well documented, it has a 186-page getting started guide pdf document which covers the fundamental skills and a strong foundation for advancement. Even if you have no CAD experience, you’ll be able to get started right away.
• 5 units systems available: Scientific, Decimal, Engineering, Architectural, Fractional.
• Export to bmp, emf, jpg, pdf, png, sld, svg( Scalable Vector graphics Format ), tif, stl( Stereolithography ) files.
• And many more…

DraftSight supports Windows 7, Windows XP, Mac OS X and Linux.

DraftSight is a 55.4MB download available from the developer’s website.

The CPU( central processing unit ) is the brain/heart of the computer, notebook, netbook, iPad, iPhone, iPod, Android mobiles and BlackBerry, it’s actually an electronic circuit, TinyCAD is a free and open source circuit diagram design software for Windows, you can use it as an alternative to VeeCAD, AutoCAD, ExpressPCB, Cadence OrCAD and Easy PCB.

Features

• Zoom in or out with mouse wheel.
• Several hundreds of predefined components( symbols ) available, including Quand NAND gates, Input NOR, Bridge Rectifier, Small Green Radial LED, NPN Transistor, LED( Light Emitting Diode ), etc. It also supports custom symbol libraries.
• Very detailed document available.
• Create PCB( printed circuit board ) net list: export the design’s netlist for import into a PCB drawing application, supported output file formats: TinyCAD, PADS-PCB, Eagle SCR, Protel, gEDA PCB, XML, etc.
• Check design rules: duplicated reference, unassigned reference designators, non-case distinct net names, etc.
• Generate symbol references.
• Export part list to plain text file or CSV file.
• Create spice net list.
• Export as png or emf picture files.
• Allows to print and print preview.
• Automatically backup every 10 minutes.
• Auto snap wires, auto drag wires, auto place junctions.
• Show the grid, snap to grid,
• Customize colors for wire, power, junction, bus, pin, no connect.

TinyCAD supports all 32-bit Windows operating systems including but not limited to Windows 7, Windows XP.

TinyCAD is a 4.4MB download available from SourceForge.net.

Early this month we reviewed TinyCAD, which is a freeware for designing circuit diagram. Logisim( LODJ-uh-sim ) is a free, open source, lightweight, easy-using, cross-platform, multi-language and portable alternative to TinyCAD which is suitable for students, it can be used to create larger circuits, hierarchical circuits and wire bundles.

Features

• Built-in tens of predefined circuit components( gates, plexers, arithmetic, flip-flops, inputs and outputs, and RAM memory ): Wiring tool, Splitter, Pin, Tunnel, Pull Resistor, Probe, Clock, Bit Extender, Constant, NOT Gate, Buffer, AND Gate, OR Gate, NAND Gate, NOR Gate, XOR Gate, XNOR Gate, Odd Parity, Even Parity, Controlled Buffer, Controlled Inverter, Multiplexer, Demultiplexer, Decoder, Priority Encoder, Bit Selector, Adder, Subtractor, Multiplier, Divider, Negator, Comparator, Shifter, Bit Adder, Bit Finder, D Flip-Flop, T Flip-Flop, J-K Flip-Flop, S-R Flip-Flop, Register, Counter, Shift Register, Random Generator, RAM, ROM, Button, Joystick, Keyboard, LED, 7-Segment Display, Hex Digit Display, LED Matrix, TTY.
• Well-documented, it comes with a beginner’s tutorial and extremely detailed document.
• Combinational analysis.
• Allows to export to PNG, JPEG of GIF image.
• Allows to use OpenGL or DirectX to accelerate the graphic processing.
• Allows to choose first/second radix when wire poked: Binary, Octal, Signed Decimal, Unsigned Decimal, Hexadecimal.
• 3 gate shapes available: shaped, rectangular, DIN 40700.
• Supports multi-language: English, German, Russian, Spanish, Portuguese.

Logisim supports Windows 7, Windows XP, Mac OS X and Linux.

Logisim is a 5.91MB download available from SourceForge.net.