Skip to content

FAQ and gotchas

Does it modify my circuits?

No. mc9.open() copies the file into the work folder; Circuit.export() writes to a new path and refuses to overwrite.

My band edge differs from what I read with MC9's cursors.

With MC9's default AC Sweep type = Auto the numeric table is coarse and linear, and cursors interpolate between its points - band edges can be off by more than 10 %. mc9 always sweeps logarithmically with 401+ points. Double points to confirm convergence.

"Node has no DC path to ground" / "label not found" / "model missing"

These are MC9's own error dialogs. When a run fails the library saves <circuit>_<analysis>_FAILED.png; read the dialog in it. Typical causes: a node connected only through capacitors; a curve like v(Out) for a node that is not named; a model name that is not in MC9's library.

Why are voltage boxes overlapping each other in my schematic screenshot?

MC9 draws them (centred on a pin of each node) and AC boxes are ~12 grid units wide. Space voltage nodes >= 14 grid units apart and build with labels="ac". Schematic.audit("ac") lists the collisions before you run anything.

Why is THD computed by a DFT and not taken from MC9's Distortion analysis?

MC9's distortion numeric table is a corrupted FFT buffer under Wine. The Distortion window is fine, so c.distortion() plus c.shot() gives MC9's own figure, while measure.thd gives numbers.

Cursor tables are cut off at the bottom.

MC9 clips the lowest table when plots are stacked. Use one plot per page for figures with cursors.

Can I use it without a display / on a server?

On Linux yes - the display is virtual (Xvfb). On Windows MC9 needs a desktop session.

Does it work with the standard English MC9?

The Windows backend does not depend on the language. The Linux backend needs a one-time calibration for editions other than the Russian GUAP build; see Supporting other MC9 editions. Reports are welcome.

mc9py only drives your own licensed copy through its normal user interface and files. It contains no MC9 code or binaries. The component definitions in mc9/templates/base.cir are the small shape/pin descriptions that MC9 itself writes into every circuit it saves.