Can anyone suggest a way i can convert voltage from a 9 volt battery into -9 volts,I dont want to switch polarities I just need a fixed circuit i can use.

 

reverse the battery leads...

 

How about using two 9 volts batteries? If you for some reason only need -9 volt remove one of the batteries

 

I'm not allowed to reserve battery polarities,this circuit will work alongside microcontrollers and OP-AMPs

 

If you only need a small amount of negative rail, you can use a capacitive charge pump circuit like the 7660 or even make one with a spare timer output on your micro driving a capacitively isolated doubler. If you have a MAX232 serial port level shifter on board, you may be able to steal a bit of V- from it.

/mike

 

The correct key word is "voltage inverter circuit"
google it you will find a lot...
The first result I got
http://www.aaroncake.net/circuits/vinvertr.asp

Good Luck

 

Can anyone suggest a way i can convert voltage from a 9 volt battery into -9 volts,I dont want to switch polarities I just need a fixed circuit i can use.

Define how much current. That determines what kind of circuit you need.