Why not use a pair of 6v photo batteries?

                -----Original Message-----
                From:   Wagner Lipnharski [mailto:wagner@USTR.NET]
                Sent:   Friday, January 14, 2000 11:18 AM
                To:     PICLIST@MITVMA.MIT.EDU
                Subject:        Re: +5 -5V Supply voltage

                Remember that "simple" doesn't mean "easy".

                The first thought about portables and small units is to use
a 9V
                battery, but 99% of the time it is not the best choice.
Sometimes
                changing from 9V battery to 3 x AA Alkaline cells (4.5V) or
4 x AA NiCad
                cells (4.8V rechargeable) is the best choice for several
reasons.  Using
                a simple ICL766X to invert the -Vcc is enough, and the AA or
AAA cells
                would give you much more power life than a 9V battery.

                The "easy" way to generate aprox +5Vdc and -5Vdc from 9Vdc
batteries
                without any extra power consume, is just open two 9V
batteries and slice
                them with a knife, then use 4 cells for the +5 and 4 for the
-5V... this
                is the easy way, but it is not "simple".

                The "practical" way is to use a step-down chip converter
(coil) and
                lucky to require a low power consume at the -5V so using a
catch diode
                to get the negative pulses, or using a real inverter like
the ICL766x...
                this is the "practical", but it is not "economic".

                Serge Marchal wrote:
                >
                > Hi All...
                >
                > I need for a project to convert from a 9V battery
                > to a +5 -5 voltage, and consume the least current
                >
                > My  question is:
                > Should I use a regulator and how can I generate a negative
voltage
                > from a regulator
                >
                > Any ideas ?
                >
                > Thanks
                > serge.