[FightCube] wrote in recommending a very helpful piece of circuit simulation software for those of you still constructing entries for the 555 design contest. LTSpiceIV, available from Linear Tech… ...

Well, you could stand to know a whole lot more after just a few minutes playing around in this browser-based electronics sandbox. The circuit simulator at Lushprojects is simple.

However, Legend's MSIM circuit simulator has been well optimized for excellent performance and memory usage. With the proven accuracy, MSIM has passed all tests with orders magnitude speed improvement ...