Roger Turk wrote:
>
> Thomas Mueller wrote:
>
> >>I notice a pack of 4 little batteries, 1.5v,
> <---->
> Four batteries would give you 6-volts. If you have a voltmeter, you can check
> to see if the batteries are good or bad. (Or go down to your nearest Radio
> Shack or ham radio store.)
Roger, Thomas if I may horn in here, I would say you are better off to use
a pack of 3 batteries instead. One of my computers uses only 2 and it works,
but that may be just luck.
The reason I suggest this is so the battery pack only gets used when the
power is off. The computer logic supply is 5 volts and if you allow 0.6
volts for a diode, then the CMOS normally sees 4.4 volts when the computer
is on. With a 6 volt battery pack, the power will come from the batteries
whether the computer is on or not - until the battery pack is near death at
under 5 volts. This could be 1-2 years.
With a 4.5 volt pack, the cmos gets 3.9 when the computer is off, (it will
work anywhere above 2.5) and the computer will take over when it is on.
There are TWO diodes involved, so the computer does not try to charge the
battery pack. (Unless it is NiCad, then it is soldered in)
Actually, in the above circuit it doesn't matter if you put the battery in
backwards, it just won't work.
WARNING ! If it ISN'T the above circuit, then get it right. <G>
Hope that wasn't more than you wanted to hear.
- Clarence Verge
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