You can check out  mirror of [url=http://www.phy.ntnu.edu.tw/demolab/CoLoS/circuitsimulator/examples/circuitbuilder.html]circuitbuilder[/url] on our site.

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The author is Toon Van Hoecke. (I am sorry that the author's web URL is not available anymore, so the link is removed).

You can find several related EJS simulations (you can download source) from [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?board=16.0]Electromagnetism[/url] board.