iCircuit for Android

No, its not precise. Components are idealized, adn some complex cnfigurations confuse it. But this thing is SO fast and intuitive ot use that its my go-to "what if" tool in actual commercial situations. Once it shows promise i can bang my head against pspice. For the $15 or so its great! I do wish that there was more bug squashing and support, but i get the business model.... But it as a learning tool, a first run "real" tool, etc.

I have bought this app for Mobile and Android. The basic functionality is there, and I really like the visualization of current flow when a circuit is completed, but all of the UI interactions feel really hard to use, a few examples: The marquee (selection) mechanism should have the option of a bounding box, the "draw a selection" behavior goes against decades of muscle memory (not to mention the polygon "winds", making a selection action that much worse). The fields for modifying a component's properties don't appear to be linked in a focus ring, and therefore I can't tab between them. Selecting a bunch of components and then dragging causes wiring to get messed up. Most of the time, I'm just trying to clean things up, but this results in the digram junctions changing. The forward-delete (on a fullsized keyboard) doesn't work to delete, only the delete key. On Mobile, the toggling between draw and delete modes is extremely frustrating, for example, adding a component, but then, tapping on it causes it to be deleted if you've left the delete mode enabled. These apps aren't cheap, and I bought the Android version because I hoped the keyboard/mouse interactions would make things easier, but honestly, the UI is almost more frustrating than on Mobile.

Really simple circuit sim, but quick and easy to use for basic electronic diagrams.

I'm breadboarding basic power supplies and a power resisor load box. This seems to work just fine so far.

I agree with Oxilumin in that the capabilities of LTspice are far greater...albeit a little rougher. LTspice, unlike most Spice variants, has a GUI for construction circuits. I use iCircuit to quickly build and test simple ciruits. I've found it faster for simple projects. Speaking of Spice, it would be nice if iCircuit would output netlists. That would make it more appealing IMO. Also the osilliscope needs improvement as it doesnt accurately portray waveforms. iCircuit a good app for simple projects. It's intuitive, easy to use, and stable. For simple circuit testing or for beginners this might be the ticket, but for any project of any complexity it isn't.