Now we're seeing a relative explosion in free tools for engineering electronics. It is easy just to hit the Net and use the myriad resources available. Some of those online tools prove to be worthless, and it's back to blind searching or some paid tool, but free software extends far beyond the functionality of a simple calculator.
To help sort out the nonsense from the useful online tools, check out the list in Figure 1.
Calculatoredge: when one calculator isn't enough
One of the more useful tools in an engineer's toolbox is a physical calculator. Why does it seem to get lost when it's truly needed? Workstations usually save the day. Those included in your OS of choice (Windows, iOS, Linux, etc.) are good for simple tasks but not so great for other things, even in scientific mode.
Searching for the right one online will net you roughly 131 million choices. Which one are you to choose when there are so many? Why not choose them all?
Almost all calculator versions known to humankind are located in one convenient site, Calculatoredge. It boasts no fewer than a few hundred calculators for just about every field imaginable (and perhaps some that are unimaginable), including electrical, mechanical, civil, chemical, and even math. There's no need to search aimlessly for that obscure number cruncher ever again. Some of the more complex calculators even come with some rudimentary instructions.
Figure 1 Calculator choices from Calculatoredge: this is only the “Electronic Engineering” panel.
Cedar Logic Simulator on SourceForge
When it's time to test simple digital logic gates and registers or even some high-level components, you can turn to Cedar Logic Simulator (still in beta edition), hosted on SourceForge, for some free online simulations. Designing circuits is great and all, but will they function correctly and perform when it counts? The Cedar Logic Simulator allows users to perform test simulations at the transistor, register/transfer, gate, and other levels.
Figure 2 Cedar Logic Simulator, on SourceForge
The software also can be used as an introductory tool for teaching logic design and an entry platform for circuit design by allowing users to drag and drop gates, inversions, and connections. There are also options for undo/redo and copy/paste functions. Projects can even be exported to monochrome or color bitmap files for project integration. SourceForge's main application window allows users to move back and forth through 10 different pages for multiple projects, making it one of the better free applications on the Web.