This is a library that allows Python applications to talk to Ngspice, an engine for simulating electronic circuits. Currently it supports sending commands to the engine and reading the results into numpy arrays, for plotting and analysis. Future goals include voltage and current sources defined by Python functions, and the possibility of stepping through a simulation in order to inspect results and modify the circuit mid-run.

Low-pass filter

Bipolar transistor output characteristics

Operational amplifier oscillator

This library requires libngspice.

On Linux, this means you have to download the source package for ngspice and compile it like this:

./configure --with-ngshared
make
sudo make install

It is occasionally necessary to adjust LD_LIBRARY_PATH to help ngspyce find libngspice. First locate your copy of libngspice.so then try updating the environment variable, with for example:

export LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH

On OSX, libngspice can be installed with brew. Note that the ngspice package does not supply the required shared libraries.

On Windows, it currently assumes that ngspice.dll is installed in C:\Spice\bin_dll (32-bit Python) or C:\Spice64\bin_dll (64-bit Python). Go to Ngspice Download and choose one of the packages (such as ngspice-26plus-scope-inpcom-6-64.7z) that contains ngspice.dll, and extract it to C:\. (To support all features, this folder structure must also include spinit, spice2poly.cm, etc.)

One fast way to produce SPICE netlists is to draw the schematic with GSchem and then export a netlist with

gnetlist -g spice-sdb schematic.sch -o netlist.net

For details on simulation commands, check out the Ngspice manual.