100% wool

a cover for an iPod/iPhone… … … a cover for what?????????????? 😀
(I saw it on the shelfs of an Apple store in the centre of Duesseldorf)

ok… take a plastic stick… scratch it into a sheet of wool… than take the stick next to some small paper pieces… what’s happening? The paper pieces stay glued to the plastic stick! Why? Because of electrostatic energy!

The effect between the iPod and the cover… is exactly the same… but… circuits… DO NOT LIKE electrostatic energy AT ALL!!!

It is crazy how… damn… “beata ignoranza”!


8 thoughts on “100% wool

  1. i like hight scholl physic so i understand the joke and i pay a lot of money for stupidity
    i’m happy boy 😛

  2. let me say 2 words about electrostatic troubles.
    in early ’70 the problem was very big because of the spreading of CMOS logic circuits.
    These circuits have an insulated gate that drive the whole thing.
    The insulation of this gate is very high (equivalent resistance is many megaohms) so it is possible to accumulate electrostatic charge on them (as explained by Zeph in his post). Since the capacity of this gate is very little (some picoFarads) the voltage (Q/C) increases very fast to values that can break the device (electrostatic discharge).
    On early ’80 the solution was found: some back-to-back zener diodes btween gates and ground or reverse biased diodes between gates and ground and vcc. The aim of the diodes is to drain the charge at a non dangerous voltage level. The only devices without this solution are low noise RF preamps (discharges and junctions are *noisy* ).
    So what is the meaning of all this?
    That the electrostatic charge is dangerous if *applied* on the devices that have not a protection.
    Charge can arrive on this gates also by induction, through insulators (as the frontal glass) but, in this case, you face a ‘capacitive divider’ and the voltage on the gates is very little, also in the case the glass touches the gate (but usually this is not true).
    So, folks: there are no really risks.
    If you prefer a Galileian approach, and you are feared for your ipod, I’ve already good news for you: Marina has an Ipod touch with the cover and the ipod is still ok and perform well …



  3. @Marina: could you try to scratch your iPod in a wool T-Shirt and tell me the result? 😀

    p.s. @Gio’: maybe you are right, could be enough isolated… but yes, seems funny they sell this stuff telling, “come on! it’s real 100% wool! wear your iPod!!!”

  4. You prefer the iPod on or off when I brush it against the wool? Anyway, I did it in both cases and I confirm: it still works. 🙂

  5. No, I’m just confident that a company like Apple (and a manufacturer like Samsung) would *never* market an electronic equipment with the potential risks you fear. Also, don’t forget that millions iPod touch have already been sold all around the world: do you really think that nobody would have complained (or started a class action against Apple) if they had had such problems? 🙂
    And, as Giovanni says, electrostatic issues are nowadays solved directly at chip level. Much cheaper than using heavy insulation in the device… 😉

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