I have problem in changing symbol of the subcircuit. I am using Qucs 0.0.15 . I followed the instructions given in
manual but I didn't succeed. Please tell me the steps in easy language (language used in help file is not so clear).
1. Create a circuit with some subcircuit ports (O- symbol; right on the toolbar)
2. Save it
3. Press F9 to change to "Edit subcircuit symbol" (or select that option from the File menu); you can go back to "Edit Schematic" pressing F9 again.
4. You'll see an ugly symbol consisting on a box with two lines and two ports. You can delete everything (except the ports) and start drawing from scratch, using the "paintings" components (lines, arcs…). You may want to edit line properties by double-clicking the lines and modifying the width and color (instead of the default 0/black, use 2/(0,0,127) to get the typical Qucs style).
5. Double-click the box that says "SUB - File=name". Here you can modify the prefix for default names (e.g. if you're modeling a speaker, change it to SPKR so that each time you insert one of these you get SPKR1, SPKR2, etc).
6. If your model was parametrized (e.g. a resistor value is just something like "R0" rather than "50 Ohm"; equations in the schematic can come in handy), you can add parameters to that box (variable name, default value, description, whether they're displayed or not by default… no idea what type is so I guess it can be left blank). Save.
7. Open a new schematic (you'll use the other schematic inside this one).
8. If you've created a Qucs project, everything on your ~/.qucs/projectname_prj/ directory will be available under Content :: Schematics. Clicking on one of these will allow you to add them to the schematic.
8-a. If you aren't using a Qucs project, you can still add a subcircuit by going to Components :: file components :: Subcircuit. Double-click it, click Browse, and select the file with your schematic. Hit Enter.
9. You'll see a component with the symbol you created has appeared in the current schematic. Double click it to customize parameters, connect it to whatever you want, and you're done. You can now use it for simulations as if it were any other component.
Thanx a lot Cousteau.