This post won't be a tutorial on electronic circuits but will present a free method to desing and simulate electronic circuits on Linux using Geda and ngspice.
To start, I will chose a simple diode clipping circuit which consist of the following elements:
2 1N4007 diodes
2 10K resistors
The schematic is available in Img 1. Note that for this circuit is mandatory to have the .mod file for 1N4007 diode.
Now, using the terminal run the following commands:
gnetlist -g spice-sdb -o diode.net diode.sch to generate the netlist
ngspice to run ngspice
source diode.net to load the netlist
tran .01ms .15ms to perform transient analysis
plot to plot the signals.
For the above circuit, the plotted signals are presented in Img 2.