For Your Technologists: CircuitLab.com
[CircuitLab.COM is free to use. Sign up is required if you want to save the circuits you have edited/created]
Draw and print beautiful schematics for lab reports. In-browser simulations make it easy to quickly learn electronics concepts via just-for-fun playing and guided exploration. Our tools complement undergraduate and graduate electrical engineering classes, as well as high school and college physics curriculums.