SymCirc

A lightweight python library for symbolic circuit analysis.

Documentation

Documentation is available on GitHub Pages.

What can it do?

SymCirc currently offers symbolic and semisymbolic DC, AC and transient small frequency circuit analysis. It supports the following ideal circuit elements: resistors, inductors, capacitors, independent sources, controlled sources, ideal operational amplifiers and coupled inductors. Transient simulation allows for initial conditions of capacitors and standard/coupled inductors.

Install

SymCirc runs on SymPy, which should get automatically installed with SymCirc. Use this command to install via pip

pip install symcirc

Build

Or you can build with this command:

python setup.py sdist bdist_wheel

Simulation example

from symcirc import *

# Insert your netlist
netlist = """
CIRCUIT NAME - First line is always the circuit name
# This is a comment
R1 1 0 2k
R2 3 0 (1/G)
V1 2 1 dc 1 ac 1
R3 3 4 6k
C1 3 4 1n
R4 4 0 10k
V2 4 0 dc 5
I1 3 2 dc 1m ac 0
"""

# Execute netlist simulation
analysis_type = "DC"  # or "AC", "TF", "tran"
method = "tableau"  # Default is "two_graph_node", which is faster, but currently lacks coupled inductors.
symbolic = True  # If set to False, only elements which have no numeric value are left as symbolic. In this case only R2 stays symbolic.

circuit = AnalyseCircuit(netlist, analysis_type, symbolic=True, method=method)

all_values = circuit.component_values("all")
latex_formatted_values = to_latex(all_values)

print(all_values)

Netlist syntax

There are many example netlists available in the netlists folder. This folder contains a database of netlists which are used to automatically test every new version of SymCirc.

Elements

• Resistor: RXXX N+ N- RESISTANCE
• Capacitor: CXXX N+ N- CAPACITY IC=<INIT_VOLTAGE>
• Inductor: LXXX N+ N- INDUCTANCE IC=<INIT_CURRENT>
• Coupling: KXXX LYYY LZZZ K
• Voltage source: VXXX N+ N- dc VOLTAGE ac AMPLITUDE
• Current source: IXXX N+ N- dc CURRENT ac AMPLITUDE
• IOAMP: AXXX Nout1 Nout2 Nin+ Nin-
• VCVS: EXXX N1 N2 Ncontrol+ Ncontrol- GAIN
• CCCS: FXXX N1 N2 VSENSE GAIN
• VCCS: GXXX N1 N2 Ncontrol+ Ncontrol- GAIN
• CCVS: HXXX N1 N2 VSENSE GAIN

Units

• terra: T
• giga: G
• mega: meg
• kilo: k
• mili: m
• micro: u
• nano: n
• pico: p
• femto: f