Really nice project Alain!
Very professional and very well designed! AdrijaD, did you notice how Alain incorporated .1 mf as well as 100mf (and other size) capacitors in his design? This is a great way to handle EMI (Electro-Mechanic Interference) / RFI (Radio Frequency Interference). As for your question about using a 7805, yes, a non-switching regulator is easier to filter the DC out. You also may wish to look at the LM123 or LM323 as the case is grounded so it is "shielded". Best, Ed