0
\$\begingroup\$

I drew a simple circuit and looked at the analogue graph. Ic drops from 12kA to 24nA after 200 us.

enter image description here I changed the start and end time of the same graph. But I looked again, Ic drops from 12kA to 24nA after 40 ns. enter image description here I don't understand, this programme cannot show the change in current or voltage in real time. Or it only shows the shape of the change. Or what did I do wrong?

\$\endgroup\$

1 Answer 1

Reset to default
2
\$\begingroup\$

Your simulation applies 12 volts instantly to an uncharged capacitor thus, dv/dt is theoretically infinite and, the theoretical current into the ideal capacitor is also infinite. The reason why the simulator doesn't give "infinite" results is because it has a minimum time step that varies depending on how you use the tool.

In short, don't ask simulators to do things that will theoretically produce infinite and impractical results. Other things you should be aware of: -

  • Most simulators like to have at least one node labelled GND
  • Voltage generators may contain a default series impedance of 1 milli ohm
  • I milli ohm would produce an initial current of 12,000 amps when the voltage is 12 volts
\$\endgroup\$

Not the answer you're looking for? Browse other questions tagged or ask your own question.