Re: Battery powered II+

[shoppa@alph02.triumf.ca (Tim Shoppa)]

In article <32EAD10F.4902@ix.netcom.com>,  <jcreid@ix.netcom.com> wrote:
>I'm working on a project that would involve running a II+ from a standby
>battery system(12V).  Since the II+ requires both +12 and -12 as well as
>+5 and -5 supplies, I'm guessing this could all be done from a decent
>deep cycle battery and some adequately heat sunk 3 terminal
>regulators(7805, 7905, & 7912).

To do this with 78xx and 79xx you need at least two 12 volt batteries.  And
you would also need low-dropout-voltage 7912's (the 13.8 V from a fully
charged battery leaves precious little left over for running
most linear regulators.  Once the battery begins being discharged,
say bye-bye to the contents of the DRAM!)

If battery lifetime, and therefore efficiency, is at all important
to you, consider switching regulators.  A cheapie 12V to 120 VAC
inverter would keep the II+ running through it's regular power
supply.  Slightly more efficient, but much more expensive, would
be to buy the necessary DC to DC converter modules from, say,
Digi-Key (http://www.digikey.com/).

Tim. (shoppa@triumf.ca)