Re: Interesting project: making the //c a true notebook computer

[mjmahon@aol.com (Michael J. Mahon)]

Roy Miller wrote:

>sirarlias@webtv.net wrote:
>
>> =="There is VERY little room inside a //c."
>>
>> No doubt about that--therein lies the real challenge. But with today's
>> smaller components and batteries wouldn't it be possible? I take it the
>> internal half of the power supply would have to be miniaturized to make
>> room for the battery.
>
>It's been a year or two since I've been inside a //c, but I don't recall an
>"internal half of the power supply". The //c+ has an internal transformer
>(is that the right word?) but it gets the room from having a 3.5" disk drive
>instead of a 5.25" disk drive.

The //c does contain a "power converter" that is about half the size of
a 3.5" mechanism.  It is needed to convert the 12-15 volts at ~1.2 A
supplied by the "brick" to the regulated +12/+5/-12 required by the
//c.  The -5 V required is regulated down from the -12 output.

As you can see, a //c cannot operate without this converter, though
it could undoubtedly be constructed more compactly these days.

The 12 volt, 1.2 amp power requirement is moderately high, and would
require a pack of, say, 1.5-2.5 AH cells.  Ten 1600 maH NiMH cells,
available in AA form factor, would do the job, and would make a flat
package about 5.5" long, 2" high, and 0.5" thick.  This could be
attached pretty neatly to the back of the //c, and would provide over
an hour of portable operation.  In a pinch, you could use non-rechargeable
alkalines!

Getting them inside the case would be a problem, though.  If rectangular
form cells were used, the thickness could be reduced and the length or
height increased to allow the pack to be 0.25" or less, which should fit
between the main board and the keyboard (if no RAM expansion were
present).  So it CAN be done--where there's a will, there's a way!

(BTW, very compact rectangular NiMH cells are available as surplus
battery assemblies for cell phones and laptop computers, natch.)



-michael

 Email:  mjmahon@aol.com
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