Simulating Circuits – More Examples!

Hope you liked my previous tutorials on SPICE simulation in Fedora Electronic Lab. Well this post comes a little late because I had a lot of circuits in mind. So take a deep breadth and get ready for Part 3! 🙂

I’m assuming that you’ve read through the previous two tutorials and that you are now comfortable with using gschem. After this tutorial, you must go through the ngspice manual atleast once. I’ll be moving a bit fast from now on because there is a lot to cover. If something is not clear, feel free to post a comment. I also assume that you’ve completed a course on analog electronic circuits. If you are currently in such a course, go through the circuits you are familiar with and come back later.

Remember to plan a directory structure before each example. Also, the models for the transistors are available from Fairchild Semiconductors and diodes from Diodes.com. I’m not posting these here due to copyright restrictions.

A quick recap:

1. You draw you circuits in gschem.
2. Generate the netlist by running: gnetlist -g spice-sdb -o <output_netlist.net>  <input_schematic.sch>
3. Always check the netlist once yourself. Also see which are the input and output nodes.
4. Simulate the circuit using: ngspice -b -r <raw_file.raw> -o <log_file.log> <netlist.net>
5. Finally open the waveform viewer by running gwave <raw_file.raw> and dragging the output you want to see to the panel.

Ready? Go!