The circuit builder simulation applet

 

Explanation:

This applet can be used to build and analyze DC and AC electrical circuits. 

When the applet is loaded a default circuit is build. It is extracted from a text file that can be found at "lists/default.txt" in the directory containing the jar files. To load another build file, type its name and press the "Load" button. To open a new window with the list of loadable text files, click here. If you want to see a text list of the elements currently on the screen, press the "List" button.

If you want to change the size of the circuit grid, change the number of rows and columns and then press the "Set grid" button. Be aware that all components on the screen will disappear.

The "Show ->" button is used to visualize arrows representing the chosen current direction.

New components for the circuit are entered by a "drag and drop" method. Press the button of the component you want to add, hold the mouse button and release it on the position where you want to put this component. Any horizontal or vertical position between two black dots can be taken.

The following direction independent components can be added:

  • Resistor: its value (in Ohm) can be entered next to the resistor button.
  • Capacitor: value entered in Farad.
  • Inductor: value entered in Henry.
  • Light bulb: characterised by voltage (in V) and power (in W). The color varies from black (no current) to white (maximum current). 
  • Wire: used to close connections.
  • Switch: can be opened and closed.

Some components need are polarised and thus have a positive and a negative side. The direction can be set by choosing "+ down/right" or "+ up/left" of the "Direction" list item. The following direction dependent components can be added:

  • Battery: value entered in V.
  • General Voltage source: its function prescription (in V) can be entered next to the source button and it default value is "sin(t*2*pi*f)". Use "t" as time variable, "f" as frequency variable and "p" as period variable. The frequency can be entered in the text field below.
  • Current Source: value entered in A.
  • Oscilloscope: simulation of a one-beam-oscilloscope. A window with the view on the particular oscilloscope can be opened by selecting the "Display Oscilloscope" option of the popup menu when you click the right mouse button on the oscilloscope icon in the circuit.
  • Voltmeter: simulation of a digital voltmeter. Use the "Display Voltmeter" option of the right-mouse-button popup menu.
  • Ampèremeter: simulation of a digital ampèremeter. Use the "Display Ampèremeter" option of the right-mouse-button popup menu.

The "Calculate" button is recalculating data. A number of "Step #" data points is calculated iteratively with a step size of "Step (s)". So the step size is entered in seconds (default is 1e-6 s).

The "Start/Pause" button and the "Reset" button are used when a real time clock is necessary. This is in situations with slow varying sources or the displaying of voltage or current graphs. The number of frames per second = 1 / (10 * step size). This is real time up to step sizes of 0.01s.

You can move a component to another position by using "drag and drop". Other actions are available as options of the popup menu when you click the right mouse button on the oscilloscope icon in the circuit. The possible options are only enabled if it is relevant:

  • Delete Component: deletes the selected component.
  • Change Value: changes the value or function of the selected component.
  • Display Value Knob: pops up a little window with a scroll bar to change the value dynamically (linear steps or logaritmic steps).
                                   
  • Display Frequency Knob: pops up a little window with a scroll bar to change the frequency of an ac source dynamically. This only works when the "f" variable is present in the function prescription.
                                   
  • Show/hide Value or Function: concerns the display on the circuit grid.
  • Set Label: gives a name to the selected component.
  • Display Oscilloscope: pops up the oscilloscope window of the selected oscilloscope.
  • Display Voltmeter: pops up the digital voltmeter window of the selected voltmeter. The mode can be switched between DC and AC (rms value).
                                   
  • Display Ampèremeter: pops up the digital ampèremeter window of the selected ampèremeter. The mode can be switched between DC and AC (rms value).
                                   
  • Display Voltage Graph: pops up a voltage graph of the selected component (use Start button). 
  • Display Current Graph: pops up a voltage graph of the selected component (use Start button).
  • Change Switch: changes the status of the selected switch: open or closed.
  • Change Polarity: switches the + and - signs of polarizable components.