Circuit Simulator

Circuit Simulator is a really useful and freely available Java applet created by Paul Falstad which simulates a wide variety of electrical and electronic circuits. The applet is available from, together with basic documentation and lots of example files. If you prefer to work offline, you can even download a zip archive containing the Java applet plus all example files.

You can either run the simulator as a stand alone Java application, or embedded within a webpage by using a Java enabled browser (see images above). The stand alone version is available from either, or by double-clicking on the circuits.jar file after downloading and unpacking the above mentioned zip file. To load the 'embedded' version, first open the example files in your browser and then select the simulation of interest.

There may be a short delay while Java is loaded the first time the page is loaded, but if an error message is displayed or you don't see the simulation, then you may need to install Java or perhaps switch to a Java enabled browser.

Getting Started with Circuit Simulator

With the default series RLC circuit displayed, click once on the switch to energise the inductor's magnetic field and then click again to see the circuit resonate as energy is transferred back and forth between the capacitor and the inductor. Notice that the flow of current is animated, with the changing colour indicating the instantaneous voltage. AC waveforms may be displayed in an oscilloscope style window, and hovering the cursor over any component will show a range of useful information at the lower right of the screen.

You can start and stop the simulation, and control other animation settings such as the animation speed, by using options available at the upper right of the applet window.

A variety of other options are available by right-clicking on the applet window, or in the case of the stand-alone applet, selecting from the pull-down menu. These are discussed below, and in related topics.

Next Steps

Circuit simulator is a deceptively powerful application, offering the ability to simulate a wide range of analogue and digital circuits. A complete file-system is included, allowing you to open any of the previously created sample files from within the applet window. It also contains an in built circuit editor which makes it easy to create designs of your own. You can import and export these circuit design files by copying and pasting from text files. If you're the adventurous sort, you can even customise the simulator by creating your own Circuits pull-down menu, allowing you to add your own creations to the existing Circuits menu system.

In fact, Circuit simulator is just one of a wide range of Java applets available from Paul Falstad's site. Educational and non commercial use of the applets is permitted, as explained on the licensing page.

Circuit Simulator Tutorials

Circuit Simulator Reference

Related Topics