Now I see. Sorry for that useless posts. EM waves are only needed if you want the sonic screwdriver work like in Doctor Who. But if you are not planning to use it as tool in your adventures then I agree the sonic waves emiter is enough.
However in MY screwdriver I would still add that=)
Well. My previous post was kinda cheeky.
Technically a sonic screwdriver should contain an adjustable sonic waves emiter that would push the bolt/nut or whatever the other thing is...
To work like in DW it should also emit eloctromagnetic waves to affect the work of computers. Also it...