> Ok, to add one more opinion to the issue of Laptop computers.
>
> In my experience, using a laptop, especially on your lap, could be
> asking for trouble, depending on the design of the laptop.
>
> One of the first devices that I found that I was electrically
> sensitive to was a 17" Apple Powerbook G4 laptop. I would get
> intense dizziness and tinnitus within minutes of using it, regardless
> of whether it was plugged in or not. Using it on my lap
> exacerbated the effect. Upon examining the magnetic field with a
> spectrum analyzer, it put out a large amount of "repetitively pulsed
> electronic noise" from directly below my left wrist near the keyboard
> area.
>
> I ultimately had to stop using it due to the symptoms.
> Interestingly, another person with a 17" powerbook G4 mentioned to me
> independently that they had symptoms when using the laptop (again,
> off power). This model is no longer produced, having been replaced
> by the Intel-based MacBook and MacBook pro line.
>
> I have since extensively used an apple MacBook as well as a Macbook
> Pro that LOOKS exactly like the Powerbook that gave me trouble, and
> neither seems to cause me much trouble even when plugged in (all
> computers bother me some). My spectrum analyzer still shows a fair
> bit of noise, but at different frequencies and pulse rates.
>
> From this I conclude that it is not just using a laptop or not, or
> if it is plugged in or not, but that the internal design of the
> laptop can also have a profound effect. Although it sounds odd, I
> have found that at least for the Apple laptops, the switch from
> motorola G4 to Intel's CPU seemed to change things enough that my ES
> is not triggered anywhere nearly as much.
>
> As Shivani has mentioned, the high frequency noise caused by internal
> power conversion circuitry seems to be a key factor in ES issues.
> While some of these are only active when the unit is powered by AC
> power, most (like the flourescent display inverter, and dc/dc
> inverters) are active anytime the laptop is in use, regardless of if
> the unit is plugged in or not. And many of these are located just an
> inch from your palms when you are using the laptop keyboard.
>
> As a result, I find my ES symptoms are least triggered by using
> either the laptop OR a desktop computer with standard (external)
> keyboard and mouse to keep my body away from the internals of the
> computer as much as possible.
>
> Finally, I would mention that I have found it useful to keep the
> actual power adapter unit for the laptop as far from my body as
> possible when using a laptop "plugged in".
>
> Hope that is useful for someone. Of course, your mileage may vary.
>
> Garth
>