fedora and notebooks? [OT]

[John Summerfield]

Dean S. Messing wrote:
> John Summerfield wrote:

owerful "undo" features of emacs.   Solution: thumbs up!
> : 
> : Touchpads are misnamed; they don't require touch. There's some kind of 
> : proximity detector involved.
> 
> I believe it is a capacitive sensor and depends on the Dielectric
> Constant of the material between the pad and one's finger.  I just did
> several little experiments to check. (I'm a scientist, after all :-)
grumble grumble[1]

> 
> First, I took my finger and put it really close to the pad w/o
> touching it.  No cursor motion. (Air has a small dielectric constant.)
> Then I took a thin piece of paper and tried to move the cursor by
> sliding finger over paper.  No go unless I pressed very hard.  Paper
> is pretty incompressible so I don't think it was that my finger was
> getting closer.  Rather the surface area of the contact was increasing
> so the capacitive effect was greater the harder I pressed.
> 
> Interestingly, through a much thicker envelope glue label, my finger
> had no trouble moving the cursor at normal pressure.  My guess is that
> the glue in between the label and the backing has a high
> Dielec. Const.
> 
> Finally, I used my finger nail.  Being an insulator, it had no effect
> even pressing hard.
>

I previously test on a G4 17" powerbook running OS X (I don't recall 
whether Panther or Tiger). I could move the cursor without touching the 
touchpad.

Now I have a G4 15" powerbook running Tiger. I can (just) touch the 
touchpad, sliding across the surface with my finger, not moving the cursor.

Non-ferrous metals seem to work much the same as fingers. Side of SATA 
cable works. Plastics (polystyrene packaging, Faber-Castell fluoro pen) 
and cardboard don't work. Neither does some insulated wire (about the 
size of wirewrap wire).

[1]
Daughter was a (just-graduated) scientist, working as a Research 
Assistant on a project involving Alzheimer's  at http://www.mhri.edu.au. 
The lead got his Ph D, the grant ran out and she needed a job. She got 
one, doing data entry for an insurance company. She's doing well for 
herself in insurance (she talks to the board), but I wish the country 
paid its scientists well, we need science more than we need good 
insurance professionals.


-- 

Cheers
John

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