LISO and Eagle on 40m machines

LISO is a circuit simulation and optimization program written by Gerhard Heinzel. It is useful for predicting the behavior of a circuit, estimating the noise, analyzing the stability of op-amps, fitting the measurement with the model, optimizing resistance/capacitance values etc. LISO is installed in /cvs/cds/caltech/apps/linux/LISO/. The LISO maual is here.

liso command

The main command of LISO is fil. It expects you to run the command always in the LISO installation directory. Since it is inconvenient, I wrote a wrapper script called liso. It is in the command search path of controls account. The script works just like fil except that you can call it from anywhere. The script takes the same arguments/options as fil. What it does is to convert given paths to absolute paths (if necessary) and change directory to /cvs/cds/caltech/apps/linux/LISO/. Then it runs fil passing the arguments given to liso.

Eagle PCB CAD

Eagle is an electric circuit schematic and PCB layout editor (http://www.cadsoft.de/). There is a free version for non-commercial use. Although its functionality is limited (board size is 100x80mm max, up to two layers, one schematic sheet), it is still useful for small projects. The free version is installed in /cvs/cds/caltech/apps/linux/eagle/ It generates high quality garber files, so that we can send them to PCB manufactures. However, the main reason I installed eagle on the controls machines is that eagle can be used as a graphical editor for LISO input files.

LISO input files are ascii text files. Usually you have to edit it using a text editor. A circuit is described as a net list. However it is not a fun to make a net list and there is a good chance of making mistakes. Using eagle's schematic editor, you can draw a schematic of your circuit, specify input and output points you want to test, specify a node where you want to measure noise and so on. Then you can convert the schematic into a LISO input file using a user language program (ULP) called liso.ulp. A preliminary version of liso.ulp was included in the LISO distribution. I enhanced it to be practically useful. I also created an eagle component library for LISO (liso.lbr) to be used with liso.ulp.

Sample session of analyzing op-amp circuit using Eagle and LISO

Open Eagle from a linux machine by typing eagle from command line.

From the left pane of the control panel, go to [Projects]->[liso-examples]->[OpAmp]. Double click on OpAmp.sch to open the schematic.

A schematic with a simple opamp circuit will show up. It is an inverted low-pass filter. To convert this schematic into a LISO input file, go to the control panel and find liso.ulp under "User Language Programs". Right click on it and select "Run in Schematic". A file called "OpAmp.fil" will be created in the same directory as the schematic (i.e. /cvs/cds/caltech/apps/linux/eagle/projects/liso-examples/OpAmp/). This is a LISO input file. To run LISO on it, go to the directory and type liso OpAmp.