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All Places > Keysight Blogs > Keysight STEM Outreach > Blog > 2018 > October > 09

One challenging aspect of electrical and computer engineering (ECE) is that electrical current is inherently difficult to visualize. Mechanical engineers see things spin and bend; chemical engineers see color changes and crystallization, and civil engineers often work on huge projects that can be seen from airplanes. ECE students, on the other hand, must use their imaginations to visualize current flow, capacitance, and inductance.

To help students visualize electronic circuits, Paul Falstad has created an outstanding electronic circuit simulator applet (

Figure 1: Paul Falstad’s Electronic Circuit Simulator Applet

The applet produces vivid animations of current flowing through circuits, and as you can see above, you can adjust sliders to modify the circuit’s LRC values. You can also open and close switches. For example, in the image below, the user has closed the switch at the top of the circuit and moved the LRC sliders, resulting in changes to the waveforms.

Figure 2: Circuit with switch closed and modified LRC sliders

Beyond basic LRC circuits

If the circuit simulator could only simulate LRC circuits, it would be a useful tool. However, LRC circuit simulation is only one of the applet’s many capabilities. To get a sense of the applet’s breadth, click the Circuits menu and explore the various sub-menus, as shown below.

Figure 3: Circuits menu

In this case, we followed the menu path Circuits > Transistors > Oscillators > Hartley Oscillator. The circuit for this oscillator is shown below.

Figure 4: Hartley oscillator circuit

Add circuit components

As if all these circuits were not enough, author Paul Falstad thoughtfully included the ability to add components to circuits via the Draw menu.

Figure 5: Draw menu

Students can choose from well over 100 components, and many of the components have customizable values. For example, you can edit the resistance of a resistor, and you can specify various parameters associated with an AND gate, as shown below.

Figure 6: Editable fields for an AND gate

In summary, Paul Falstad has produced an outstanding animation tool to help students understand electronic circuits. The huge variety of circuits simulated and the richness of the app’s feature set provides virtually limitless opportunities for student experimentation and learning.