Re: Popular Science

[Rubywand <rubywand@swbell.net>]

Mitchell Spector wrote:
> 
> In article supertimer@aol.com (Supertimer) writes...
> 
> >I have not tried freezing the TWGS just yet because of the
> >condensation issue....is there a way to put it in the freezer without
> >it getting wet?  Just the CPU is ok because I can wipe it before
> >plugging it back in, but a whole card...the moisture would ruin it!
> 
>     Be warned, it is NEVER a good idea to use any type of electronics
> after they've been exposed to extreme cold. Condensation is certainly
> one issue, having something that is extremely cold suddenly get very
> hot (or visa-versa) is yet another. You might experience something
> similar to when you pour boiling water in a glass jar and place it
> in a freezer, where it expands or contracts too quickly. :)
> 
>     When I originally got my Apple IIgs, it had been sitting in the
> trunk of a car during most of the day in the middle of January (up
> here in Montreal, Canada, temperatures can commonly drop to -20/-30
> celcus on cold winter days). I was too eager to let it reach room
> temperature, and immediately unpacked and assembled the IIgs right
> after taking it inside. After using it for a few hours, the entire
> logicboard blew. Luckly I was able to get the board swapped under
> warranty the next day, but I learned that lesson the hard way.
> 

     Agreed. The usual reason for special cooling in high-perforance
processor cores is so that you can clock them at higher speeds without
frying the semi-conductors. A more arcane scenario is that you are
running a super-conductor circuit.

     For standard LS-TTL, NMOS, and CMOS IC's, it is a good idea to use
heatsinks, fans, etc. to help dissipate heat for chips which tend to run
hot. Unless a particular IC on a board is being clocked at a frequency
beyond the original design specs, just normal cooling-- e.g. via a
SystemSaver IIgs-- should be adequate.

     Cooling standard IC's to freezing is a bad idea. Transistors and
diodes in standard IC's are not qualified to work correctly at very low
temps. Some circuits which normally snap into oscillation may fail to do
so, and it is possible to have other high-current conditions which may
damage a circuit. Your idea of possible uneven expansion during warm-up
is something else to consider as a source of breaks and shorts.

       

Rubywand