Toralf Lund wrote: >>But it IS driven by ultrasonic frequency AC. > > My point is that an AC frequency can't be "ultrasonic" since electricity > isn't sound. The vibration in a piezoelectric setup, on the other hand, > in a way is. > > - Toralf >
Then there are no USM motors by your definition, which is incorrect btw. Ultrasonic is jargon, referring to frequencies just above the hearing range of humans. So an AC frequency above approximately 22KHz would be Ultrasonic. Note that driving a motor with AC current and a frequency within the human hearing range will produce audible noise. So there is good reason for this terminology. -Adam -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
