need to find a program to simulate circuits, forgot what it is.

[XOIIO]

Hey all, I remember a somewhat basic program that allowed you to construct circuits, and actually "test" them, showing the flow of electricity. I mostly remember it had a black background and electrons were shown as yellow dots.

Hoping to find this ASAP, looking myself but not having much luck, maybe someone here remembers it. I know it was free, can't recall if it was a download or web based, I think a download.

[XOIIO]

found it! http://www.falstad.com/circuit/