From: Bill Morrow (penzance_at_icanect.net)
Date: Thu Jul 22 1999 - 00:09:34 EDT
ummm...
as a practical matter, i have and will continue to use AC adapters from
the 755, 701, 560, 600 and various 770's and any or all of the
preceeding machines.. with, to date, no apparent thermal damage..
in fact, i have not had to send any thinkpad (yet) for service due to
electronic failure..
James wrote:
> Bill and Juan-Carlos,The point I was trying to make is that "more
> amp is not necessary better than less" as Bill have indicated in his
> original posting. And the reason is because it causes thermal
> breakdown. Thermal breakdown occurs when there is an excess amount of
> current across a cross area of a conducting medium per unit second. In
> semiconductor language, what this means is that the current causes an
> the rate of charge separation is faster than the rate of
> recombination. Above all, the point is that "more amp is not necessary
> better," a concept that all devices or electrical engineers should
> know. Like what Juan-Carlos said, assuming resistance is constant,
> then the voltage across the device determines the amp passing through
> it. ThanksJames
>
> ----- Original Message -----
> From: Juan-Carlos Lerman
> To: James ; thinkpad_at_cs.utk.edu
> Sent: Wednesday, July 21, 1999 3:59 PM
> Subject: Re: Interesting TP accessory prices
> orialy21 said:
>
> > In most cases, more amp is not better because it could
> > lead to thermal breakdown unless your device is
> > designed to run on reverse bias - as some diodes are.
>
> Can you explain what do you really mean and how
> does it relate to the problem?
>
> It's my (poor) understanding that the power adaptor
> is a constant *voltage* source, not a constant
> *current* source.
>
> In consequence the amperage drawn from it is only
> dependent on the resistance of the device connected
> to the output of the power supply.
>
> And this follows Ohm's law:
>
> current(in amps) = voltage(in volts) / resistance(in ohms)
>
> In other words the adaptor will supply the device
> with any amperage as required by the device, up
> to the maximum value indicated on the label. Above
> that, expect thermal breakdown.
>
> JC
>
>
>
>
> ===
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-- Live Long and Prosper, Happy trails...** Bill Morrow ** :-) WEB page http://thinkpads.com Thinkpad User Community: http://thinkpads.com/enter.html Compuserve Thinkpad(c) Forum Sysop e-mail: bill_at_thinkpads.com, penzance_at_icanect.net 770Z-8AU, 760ED, 760CD, (5)701C, 560E, 755CE, 750C et al...
Including, but not limited to, Subject to prior sale, Your mileage will vary, Done on a closed road with a professional driver AND Do not try this at home..
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