Why does my MP130/MP2000/eMate whine when the backlight is on?
(From Robert Sexton’s FAQ) Backlit Newtons use the same technology that is found in indiglo watches. The backlighting uses high voltages, and this requires a transformer which makes the noise. If you listen carefully to an indiglo watch, you will notice the same effect. Apple published a tech note about it: http://docs.info.apple.com/article.html?