Barry's RLC Simulation

This is a Java simulation of a classic RLC (resistor - inductor - capacitor) circuit. You should see an applet (below) with slider controls to adjust the parameters, which will control a graph of inductor current during its initial response.

About the RLC Simulation

This is a "simple" circuit to let you play with various component values and see what happens. It simulates a RLC circuit alone, without the projectile. This coil has constant (fixed) inductance throughout the simulation.

Your goal in this little game is to find a combination of values which result in maximum peak coil current, and which also dies away to near zero in about the time it takes the projectile to pass the mid-point of your coil. Good luck!

So you probably need to estimate first how much time is needed. Look at a crude timing estimate for one approach to get some ballpark figures.

The program will auto-scale the vertical axis to show multiples of 4 and 10 amps. Also, it will auto-scale the horizontal axis based on the natural frequency of the tuned LC circuit. It will display enough time for at least 2 complete cycles, and up to about 8 cycles. Be sure to read the axis labels carefully to understand the scales.

This is the same RLC circuit which is typically analyzed in standard introductory engineering courses. It is a well-understood circuit, and you can find books and equations to describe its characteristics all over the web. Please see my analysis on my next web page for some general comments about how this is adapted to coilguns.

Trouble?

Are you having a problem running the applet? This program requires Java Runtime Environment (JRE) 1.4 or above. You can download the latest Java executables from Sun Microsystems at http://www.java.com/en/download/manual.jsp Look for your operating system and click its "download" link.

If my applet still doesn't work, try to open your Java Console window in your web browser. The console icon will usually look like a steaming coffee-cup. Copy and paste its contents into a message and e-mail it to me for trouble-shooting.

About the Program

This program solves a first-order linear differential equation, by numerically computing the change in voltage and current in each small increment of time. In July 2000, I added a fourth order Runge-Kutta solution for improved accuracy. This reduced the number of steps, gave better performance, and eliminated some divergent tendencies.

The program was written with IntelliJ (www.intellij.com) using Swing classes. My Java source code is open and freely available in CoilSim20.zip (20KB).

I want to keep the Internet clean so please report bugs, request features, make suggestions and send me compliments about the simulator.