DiaCanvas is a generalized version of the drawing canvas used by DIA. It extends some features used by DIA and adds new ones, while preserving as many of the original features as possible. This project is no longer actively maintained. It is suggested that you try DiaCanvas2 instead.
gEDA is a suite of electronic design automation (EDA) tools. Currently, the project offers a mature suite of free software applications for electronics design, including schematic capture, attribute management, bill of materials (BOM) generation, netlisting into over 20 netlist formats, analog and digital simulation, and printed circuit board (PCB) layout.
HDLmaker generates hierarchical Verilog and VHDL code, PCB netlists, simulation and synthesis scripts/projects/make files, and schematics. It can translate Verilog/VHDL and HDLmaker projects into HTML, including extensive hyperlinking between the modules. It can also translate PADS PCB netlists into Verilog and VHDL and can do some simple VHDL to Verilog translations. HDLMaker synplifies the development of complex FPGAs and ASICs, and has extensive support for most Xilinx FPGAs.
Ngspice is a mixed-level/mixed-signal circuit simulator based on three open source software packages: Spice3f5, Cider1b1, and Xspice. Spice3 is the most famous and widely used circuit simulator. Cider is mixed-level simulator that includes Spice3f5 and adds DSIM, a device simulator. Cider couples the circuit level simulator to the device simulator to provide greater simulation accuracy (at the expense of greater simulation time). Xspice is an extension to Spice3 that provides code modeling support and simulation of digital components through an embedded event driven algorithm.
XCircuit is a UNIX/X11 program for drawing publishable-quality electrical circuit schematic diagrams and related figures, and producing circuit netlists through schematic capture. XCircuit regards circuits as inherently hierarchical, and writes both hierarchical PostScript output and hierarchical SPICE netlists. Circuit components are saved in and retrieved from libraries which are fully editable. XCircuit does not separate artistic expression from circuit drawing; it maintains flexiblity in style without compromising the power of schematic capture.
Transcalc is an analysis and synthesis tool for calculating the electrical and physical properties of different kinds of RF and microwave transmission lines. It uses GTK+ for its user interface. For each type of transmission line, it presents you with dialog boxes which allow you to enter values for the various parameters, and either calculate its electrical properties (analyze) or use the given electrical requirements to sythesize physical parameters of the required transmission line.