Forums » CircuitLab Feature Requests

If it is required to accurately simulate an AC circuit with multiple sources, CircuitLab should respect the amplitudes set on the sources.

At present in a frequency domain simulation, CL plots 'gain' (output/input) referred to only a single AC source of a fixed 1V amplitude.

i) When running a frequency domain simulation, CL assumes an input signal amplitude of 1V and so plots the gain of any circuit rather than the actual magnitude of the AC signal.

ii) a response to only one AC source can be plotted at a time. For any circuit that contains more than one AC source, the combined response to all sources cannot be plotted.

Both of these behaviours are different from how most simulators treat AC sources.

For more background on this request please see this thread:

https://www.circuitlab.com/forums/support/topic/wbdsx6m6/frequency-graphing-amplitude-problems/

And there's a more subtle problem ...

Please see:

https://www.circuitlab.com/forums/modeling-and-simulation/topic/vsuz86e2/another-question-about-ac-analysis-with-multiple-sources/

Hi all,

Just wanted to let you know that we've just added a little more flexibility to the AC analysis input specifier which should solve these issues. In the "Frequency Domain" tab, under the "Input" specifier where you'd normally type "V1" or "Vref1", you can now optionally specify one or more phasors, for example, "V1 20 -90 I1 5 0", which specifies V1 with magnitude 20 and -90 degrees phase and I1 with magnitude 5 and phase 0. Also see this discusison.

@mrobbins and the rest of the team at CL,

Great work, many thanks and Happy Christmas!