So, I can replace 33uF with 22uF, am i right? Or I can say inpetence becomes biger if I change 33uFinto 22uF.
Thanks

The size of the capacitor determines the ripple at the input, nothing more.
You select the size to get the maximum ripple the circuit can tolerate.
More ripple also creates more EMI, if that's a problem.

 

I don't disagree with anything here.
My point was that you can't use the usual value for RMS AC voltage into a constant-current load and get the correct value of power.
You need to use the average value of the voltage.

Hi,

Oh, i didnt think we had a constant current load, but ok, if the voltage is constant then that's ok, and the voltage might be 'fairly' constant so it might work for this too. No problem then

For what it is worth, whenever i do simulations i always use the definition of power (the integral of instantaneous current times instantaneous voltage, times the inverse of the period) because that is the only thing that covers all waveform cases, even with ripple or whatever. That way i can calculate the efficiency (doing both input and output).