Quick Start

Create your netlist

Before actually using this program, you will need to write the circuit you want to analise as a netlist. This software uses a netlist style similar to SPICE programs, where each line corresponds to each component in the circuit. They will be formatted like VIN IN 0 V, where:

  • The the first letter in the first word, V is the component type (V for voltage source, R for resistors, etc), and together with the other letters, VIN, make up the component name. More on here.

  • The second and third words are the nodes the component is connected to. Their names are arbitrary, except for the node 0, which will always be ground. It is also always necessary. More on here.

  • The final word will be the value for the circuit. It can be a literal (such as in this case, V), a numeric value (like 10k), or a combination of both (like 10VIN). More on here.

For example, here is a RLC circuit, and its netlist:

RLC Circuit 
V1 1 0 10
R1 1 2 1k
L1 2 3 100m
C1 3 0 10u

While simple, there are some caveats when writing the netlist for a circuit. You can read the full documentation on netlists for this software here.

Usage

After creating the netlist, store it into a netlist.cir, and choose how you intent on using this software:

Command Line Interface

The basic usage for the CLI software is in the form:

rtds-circuit-analysis netlist.cir

This will print all the solutions for the circuit (node voltages, currents, states, etc). You can use flags to filter the output. For example, to show only the currents for each component, you can run:

rtds-circuit-analysis netlist.cir -i

You can filter it even more, by giving the components/node names to the flags as parameters. So, if you want the voltage and current for the resistor R1 only, you can run:

rtds-circuit-analysis netlist.cir -v R1 -i R1

To take a look at every flag available, run the help command:

rtds-circuit-analysis -h

For a more in depth explanation on how to use the command line interface, click here.

Library

To solve the circuit, you need to import the Circuit class, and pass the netlist as a parameter, creating a circuit object.

from rtds_circuit_analysis import Circuit

circuit = Circuit("netlist.cir")

This circuit object will have all circuit solutions stored as attributes. So, for example, to find the voltage at node “2”, you can use:

circuit.node_voltages["2"]

You can also use the print methods to print the solutions for the circuit in a formatted manner, similar to the CLI. For example, to print the voltages for the components R1 and R2, you can run:

circuit.print_component_voltages("R1", "R2")

For a more in depth explanation on how to use the python library, click here.

Output Examples

Some examples of the full output for some circuits and their netlists:

Voltage Divisor

Voltage Divisor

Netlist:

V1 IN 0 10
R1 IN OUT 6k
R2 OUT 0 4k

Output:

*** Currents ***
V1 --> 1/1000
R1 --> 1/1000
R2 --> 1/1000

*** Voltages (components) ***
R1 --> 6
R2 --> 4

*** Voltages (nodes) ***
IN --> 10
OUT --> 4

*** This circuit is stateless ***

RLC Circuit

RLC Circuit

Netlist:

V1 1 0 10
R1 1 2 1k
L1 2 3 100m
C1 3 0 10u
.STEP 1e-3

Output:

*** Currents ***
V1 --> IL1
R1 --> IL1
C1 --> IL1

*** Voltages (components) ***
R1 --> 1000*IL1
L1 --> -1000*IL1 - VC1 + 10

*** Voltages (nodes) ***
1 --> 10
3 --> VC1
2 --> 10 - 1000*IL1

*** State equations (continuous) ***
dIL1/dt = -10000*IL1 - 10*VC1 + 100
dVC1/dt = 100000*IL1

*** State equations (forward) ***
IL1_{n} = -9*IL1_{n-1} - VC1_{n-1}/100 + 1/10
VC1_{n} = 100*IL1_{n-1} + VC1_{n-1}

*** State equations (backward) ***
IL1_{n} = IL1_{n-1}/12 - VC1_{n-1}/1200 + 1/120
VC1_{n} = 25*IL1_{n-1}/3 + 11*VC1_{n-1}/12 + 5/6

*** State equations (trapezoidal) ***
IL1_{n} = -17*IL1_{n-1}/25 - VC1_{n-1}/625 + 2/125
VC1_{n} = 16*IL1_{n-1} + 23*VC1_{n-1}/25 + 4/5