Hi,
Assuming (big assumption here) that the current needed for the negative supply is minimal and yoyu wish to run it off just one battery, you could try a simple (and inefficient) 555 timer negative voltage generator:
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http://www.armory.com/~rstevew/Public/PSUs/-vgen.html
These convert a positive voltage to a negative voltage...meaning +5v supply -> +5v and -5v.
The negative voltage regulator you mentioned (maplin) requires a negative voltage input. So, if you use two 9v batteries, one for + and one for -, both rails would require regulation down to 5v. The 7905 regulates the negative rail, and the 7805 regulates the positive part
Similar to this setup:
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You 'could' use 8 AA batteries (12v), in series, which are tapped halfway, to give a GND. Then you'll have +6v and -6V, which you could then reduce down to about 5.4V using a diode. Or 4.8V using two diodes in series.
Many opamp designs that require a dual power supply (positive and negative with respect to gnd) use a simple voltage divider to give 4.5v from a 9v battery. That 4.5v becomes a virtual ground, the - form the battery becomes the -4.5v and the + becomes +4.5V. Although, that really does limit the current, and its particularly inefficient, for comparators, it should do just fine, that is if you can get away with not quite 5V, and do not wish to 'power' anything current hungry with it.
Aside from all the above, you can get negative voltage 'modules' which are fully enclosed switch mode power supplies in themselves. Their efficiency is around 75-85%, they're big and expensive.
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As for a 'chip' that will do what you want, I've used this with great success...but read the datasheet for current capabilities:
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Please note that most of the above will produce a negative voltage, similar to that of the input voltage. That is, if you put 9v in, you'll get about -9v out. You require +/-5v...so you could regulate the 9v down to 5v first, with a 7805.
There are so many ways to do this, just depends on what power supply you have available,one 9v battery? don't mind using 2? AA's, plug in PSU...
Well therse some idea's anyway.
Blueteeth