To simulate a circuit
The source code are based on the Paul Falstad code. Code can be found on : http://www.falstad.com/circuit-java/ site.
The terms and conditions for the original code still apply. Check http://www.falstad.com/licensing.html before redistributing or modifying the code. You must always consult the original licensing information but, in case the link is unavailable, here is a copy of the original license (as of 10/04/2019):
You have permission to use these applets in a classroom setting or take screenshots as long as the applets are unmodified. Modification or redistribution for non-commercial purposes is allowed, as long as you credit me (Paul Falstad) and provide a link to my page (the page you found the applet(s) on, or http://www.falstad.com/mathphysics.html). Contact me for any other uses. The source code for each applet is generally available on that applet's web page, but some of the applets use third-party source code that has restrictions.
THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.