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Battery voltage regalted power supply with positive and negative output

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Battery voltage regulated power supply with positive and negative output

I would like to design a cost effiecient and effective voltage regulated power supply, such that i can have +12V and -12V output.
But the challenge is that i am going to use a +12V Battery as source [No AC source].Well my design in my mind is:

BATTERY--->REGULATOR---->[ +12V, GND ]and [-12V, GND]


can anybody give your suggestion??? i don't want to use readymade costly chips, but i tried to use regulators like 7812 or 7912.. but the challenge was finding the ground..:???:
circuits with OPAMP or transistors might be very much appreciated.

looking forward for your suggestions.
 

It appears that the maximum input voltage will never cross 12volt as you are using 12volt battery. So why you are using LM7812 etc. which needs 2v dropout voltage to work.

https://www.edaboard.com/threads/170326/

Switched DC to DC converters offer a method to increase voltage from a partially lowered battery voltage thereby saving space instead of using multiple batteries to accomplish the same thing.

**broken link removed**
 
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±A 12 volts battery is itself a regulated supply except for the reducing voltage on continuous use. If you add a 12 volts regulator you need to raise the input voltage by 2 volts from the output which means you have to have 14 volts minimum to get 12 volts out from the regulator (as said by papunblog in post #2). And if you use only one battery you will not be able to get -12 volts as the common can be connected to same load. Better you use either 2 batteries to get ± voltage source or you have to use (for better efficiency) a switch mode power supply.
 
Thank you for your reply!!
i liked the idea for desiging a DC DC convertor with a 555 timer.. this can give me a cost effective idea.. i will try this..

"If you add a 12 volts regulator you need to raise the input voltage by 2 volts from the output which means you have to have 14 volts minimum to get 12 volts out from the regulator (as said by papunblog in post #2)"

But there was spark in my mind after reading your comments.. why does a regulator reduce 2 volts than its regulated power supply[].. [this is new fact for me].. can anybody throw some light on this, explaining why??
 

For LM7812, Minimum supply voltage(Vin) is 14.8 and Max V1n is 27Volts

This is called Dropout voltage- It is the minimum difference between input voltage and output voltage for which the regulator can still supply the specified current.

Another type of voltage regulators are LDOs--- A Low Drop-Out (LDO) regulator is designed to work well even with an input supply only a Volt or so above the output voltage. The input-output differential at which the voltage regulator will no longer maintain regulation. Further reduction in input voltage will result in reduced output voltage. This value is dependent on load current and junction temperature
 

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