How to achive mutual inductance and CM choke simulation in CircuitLab?
(CircuitLab simulation engine author here -- just noticed this question!)
CircuitLab does support coupled inductors. Define a Parameter Element with a name like &quot;K L1 L2&quot;. For example:



simulate this circuit &ndash; Schematic created using CircuitLab
(Example adapted from: https://web.cecs.pdx.edu/~tymerski/ece222/How%20to%20create%20a%20transformer%20using%20LTSpice.pdf)
It can also handle multiple inductors, and you can even do parameter sweeps over the coupling coefficient, for example:



simulate this circuit
(Example adapted from: https://web.cecs.pdx.edu/~tymerski/ece222/How%20to%20create%20a%20transformer%20using%20LTSpice.pdf)
Lp, Ls1, Ls2 effectively form a center-tapped transformer. If you run the simulation, this second example shows a parameter sweep which allows you to compare the results for different values of the coupling coefficient.