frequency domain study with external circuit

Hi

The comsol model gallery includes a frequency domain model of a capacitor. I added an external circuit coupled to

the capacitor and a time dependent study runs OK (as shown in a separate gallery model).

Now say I have a voltage sine source in the circuit, how do I run it in a frequency domain study?

Is it possible?

I keep getting errors. Must I define it as an AC source and run it in a time dependent study ?

thanks

David