# LC Time Simulation

What if you have your capacitor, and know the desired discharge time? This page helps design your coil by telling you the inductance needed for the discharge time. Note the timing does not include effects of a projectile.

## Assumptions

This applet applies to low-resistance circuits. That is, it assumes the discharge is essentially sinusoidal, as is the case with under-damped RLC circuits. A small amount of resistance will not significantly change the timing, as long as R2C2 < 4LC.

It solves for time by using the basic equation for time T in an LC resonant circuit:

If your circuit is critically damped or over-damped, don't rely on this applet. The timing will be a little slower than shown here.

## LC Time Simulation

This program calculates time by solving the formual (above) for inductance. For example, the zero-crossing formula for inductance in an undamped LC circuit works out to be:

T2
L = -------------
pi2 * C

where T = time in seconds, pi is 3.14159, and C is capacitance in farads. The inductance L is in henries. The formula is simple; however the Java applet source code got a bit messy by showing values in engineering units.

Your goal in this simulator is to choose the inductance. Use this value to design your coil. (Hint: See the next page!)

Do you like this? Tell me thanks by funding a trip to Starbucks for my favorite mocha. Click the PayPal donate button above to send \$5 and I'll be very grateful. I can convert coffee into software and wine into headaches.

What do you use this LC time simulator for? Write me - I'd like to hear!

## All You See Is a Big Gray Box?

This program uses Swing and requires Java Runtime Environment (JRE) 1.4 or above. The current version is Java JRE 7u7 as of October 2012 and these applets are 100% compatible.

If you see a red "X", you should update your JRE. You can download the latest from http://java.sun.com/j2se/1.4.1/download.html and scroll to the "Standard Edition" section. Download and install the JRE, or if you write Java code then get the software developer's kit (JDK) instead.

If you still see a red "X", then Sun Java may be conflicting with Microsoft JVM. Open "Add/Remove Programs" and remove Microsoft Java Virtual Machine. It is obsolete -- Microsoft has not been maintaining it since Sun had a successful lawsuit against them.

If my applet still doesn't work, open your Java Console window in your web browser. Copy and paste its contents into a message and e-mail it to me for trouble-shooting. The first few lines are especially useful since it identifies your version of Java.

## About the Program

The program was written with NetBeans 3.5.1, (a free download) using Swing classes. The source code is freely available in these files:

Comments and feature requests are invited! Send them to Barry.

 < Previous Page 5 of 17 Next >