I have been following ktechlab, ever since it nearly was born. Seen the original Authors work on this program. After which the maintainer gave up; on the program and passed it to the new maintainer. Now the new maintainer is struggling. To keep ktechlab up and running as before. I have found another interesting project: http://www.kde-apps.org/content/show.php/Keda?content=59527.
If the project is stopped for ktechlab I do have a wish. The wish for the current maintainer before shutting down. Actually copying all the work from ktechlab.org to sourceforges project page. Where it would still be up, hosted on sourceforge. So anyone could pick up the work! I'm surprised that we have gazillion text editors. Yet something as scientific as this program is a commodity.
On windows you have number of programs of course shareware. Such as: Tina,Circuit Wizard, Crocodile clips (more students tailored) and others floating around. Qucs is another open source circuit simulator. However it does not really do the simulations as Ktechlab does. It is not a WYSIWYG simulation. Mweehh I do not like that program as much. Perhaps it has some expansion for the ktechlab type simulation. Which may happen some day, although I did email the main maintainer. They did not have any plans to add the said things. GEDA's maintainers do not even see it in the future to do such a thing at all. They will continue to be stubborn, or have very little man power. Who knows? but it is not taking off either.
Although looking at some parts of that app is promising. But it is only PCB and circuit design and such. The simulations are very weak in linux it seems at this time. Creating such a program is not piece of cake either however. For each redundant none scientific app like to see a scientific app. Anyhow the open source is great but could use more available man power on the science front. Esp Electronics the obsession is so much with other fronts. :-)