MessagePad and eMate: Noise Emission Levels

I have several Apple MessagePad devices, which emits a high pitched buzzing sound. What is causing this?
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Sophisticated technology used in the design of the Newton MessagePad and eMate, allows these devices to operate with very low power requirements.

The design in essence requires a rapid power-on power-off cycle - which in turn emits an audible signal. This signal can be heard in quiet environments, or in the case of the eMate 300, seem more pronounced when using headphones. This noise can be described as a buzz, static or high-pitched whine.

This level of noise emission is at very low decibels and is well below industry standards.

There are a few additional notes concerning noise emission depending on the model you own.

On the Apple MessagePad 110, 120, and 130, the sound is strongest from the foot of the device where the charging contacts are located. This sound is related to the power manager and will pulse off and on with use. This sound is normal.

The Apple MessagePad 130 and 2000 normally emit additional noise when the backlight is on. You may notice the sound when the MessagePad devices are in a quiet environment, or if you are more sensitive to the frequency being produced by the MessagePad devices. Again, this noise emission is normal.

The larger screen on the eMate 300 requires more power, which will in turn result in a louder audible tone associated with the power-on power-off cycle. As with the MessagePad 2x00 series, backlighting will create additional noise, and may be more pronounced than the smaller MessagePad screens.
Published Date: Feb 18, 2012