Does the Velleman K8064 need a filtering capacitor with arduino PWM or not?

megamasha:
OK, I'm trying to settle this issue here, once and for all. Also, I need to know which additional parts I should order.
If you know the answer, I IMPLORE you to reply, as googling throws up so many similar unanswered questions.

Here, massimo suggests using a capacitor.

Here, Magician says it's unneeded.

Can anyone lay this to rest please?

Thank you,

mm

Well my opinion matches Magician's. Looking at the schematic of the dimmer in it's owner's manual I see a low pass filter in the output stage of the opto-isolator. So adding further low pass filtering upstream probably won't buy you anything and therefore not required.

Lefty