Division of two signals in the analysis plot pane

[Sphyrnidae]

Hello,

is there a trick to divide two signals in the plot pane? Subtraction and addition is working.

Kind regards,

S

[holger]

There is a bug, either in Eeschema or in ngspice. I will check it.

For now, don’t label the node by ‘out1’, but for example by ‘outa’.

Or you may use global labels instead of netlabels.

[Sphyrnidae]

Hello Holger,

it’s still not working with renaming to ‘Outa’:

Using global labels isn’t working too:

And I would like to kindly ask if there’s a possibility like in LTSpice to add several plot panes to one analysis tab? This is really helpful if the signals are on different DC-levels:

The simulation:
JFET.zip (14.1 KB)

The used JFET model:
jfex140.lib (2.4 KB)

Kind regards,

S

[holger]

The “trick” of the global lables is that the node now is called ‘out1’, not ‘/out1’ (This helps ngspice by avoiding math characters like ‘/’ in a node name). So you have to adapt the ‘user defined signals’ to the new node names (without ‘/’) as well.

Your JFET.zip is running, but delivers another error meaasge. V(/out1)/V(/G) is running out of range, as V(/G) will be 0 at some point in time (KiCad 8.0.4 on MS Windows).

...
v2#branch                          5.31501e-11
 Reference value :  0.00000e+00
No. of Data Rows : 1008
Background thread stopped with timeout = 0
let user0 = V(/D)-V(/S)
let user1 = V(/Out1)/V(/G)
Error: argument out of range for divide
in term: V("/Out1")/V("/G")
Error: Can't evaluate " V("/Out1")/V("/G")"

Several plot panes are currently not supported. You may employ ‘user defined signal’ instead by adding an offset. There is already a wishlist item at whishlist: support dual plot pane in simulator (#15960) · Issues · KiCad / KiCad Source Code / kicad · GitLab. You may give it a ‘thumbs up’.

[Sphyrnidae]

Hi Holger,

thank you for your reply. You are correct there is a division by zero, which leads to the error. If you shift the DC it is doing fine:

I gave a thumbs up. Thank you!

S.