Electronics and Telecommunication Engg

Octave

Homepage: http://www.octave.org/
License: GNU GPL
Description:
GNU Octave is a high-level language, primarily intended for numerical computations. It provides a convenient command line interface for solving linear and nonlinear problems numerically, and for performing other numerical experiments using a language that is mostly compatible with Matlab. It may also be used as a batch-oriented language.
Octave has extensive tools for solving common numerical linear algebra problems, finding the roots of nonlinear equations, integrating ordinary functions, manipulating polynomials, and integrating ordinary differential and differential-algebraic equations. It is easily extensible and customizable via user-defined functions written in Octave's own language, or using dynamically loaded modules written in C++, C, Fortran, or other languages.
Online Manual
FAQ's
Examples
Contribute to Octave

TinyCAD

HomePage:http://tinycad.sourceforge.net/
License: GNU GPL
Description:
TinyCAD is a program to help you draw circuit diagrams. It comes complete with symbol libraries to get you started straight away. As well as being able to simply print your designs, you can use TinyCAD to publish your drawings by copying and pasting into a Word document, or saving as a PNG bitmap for the web.

You can use TinyCAD as a front end to a PCB layout program (see the links), by getting TinyCAD to create a netlist of your circuit.
[Online Manual http://tinycad.sourceforge.net/support.html]
[FAQ's http://tinycad.sourceforge.net/faq.html]
[Examples http://tinycad.sourceforge.net/screenshots.html]
[Contribute to TinyCAD http://tinycad.sourceforge.net/Sourceforge.html]