Simulator fails to simulate Inductor (But works if the L is substituted by R)

Schematic Simulation (Ngspice)
1

Hi,
I am having a problem, where I cant simmulate a incuctor.
I have attached a Picture.
When I switch the incductor for a resistor it works, but when I place the inductor (coil) it will not run the simmulation (See attached
LOG.txt (31.8 KB)
logs)
Thanks in advance for helping!.

Screenshot 2024-10-17 150311
Screenshot 2024-10-17 1503111458×739 38.3 KB

2

Warning: singular matrix: check node probe_int_unconnected-_r8-pad1__r8_1

ngspice tries to simulate R8, but it cannot find its operating point (how should it be successful?)

Mark the resistor by ‘Exclude from simulation’ in the ‘Symbol Properties’ window.

3

Place a 1Meg resistor across the inductor to help the solver converge

4

R6 is actually 10 milliohms. A quirk with KiCAD. Use 10000k instead.
Same with R9. 1 milliohm. Use 1000k.
And what’s the value of L1?

1 Like
5

V9 handles this conversion of M → Meg for you for simulation. Not sure about V8 though.

6

It also works for KiCad V8, and has so for multiple KiCad versions.

image

I think it has to do with one of those “compatibility modes” for the simulator. I searched the ngSpice Manual but all I could find in the manual is reverences that it should not work, so I assume this is caught and translated before the data goes to ngSpice. But it’s always something to keep in mind and verify when doing a simulation. Just another one of those silly details you have to keep track off. But 9 orders of magnitude difference is likely to get noticed really quickly.

7

Actually a quirk of SPICE

8

Thanks this and and Naib answer solved the problem. Thanks again

1 Like