making -9V supply

Hi I need to create power supply from batteries only with +9v, and -9v for input into an opamp and LM565 PLL


How can I do this?? Please help

Easiest and Cheapest way is to use Two Batteries in series. Zero Volts is the junction between the two batteries.

that won't be very reliable though, because unequal loads on the + and - supplies will cause the batteries to discharge at different rates.

you could use a MAX660 and provide it with +9v, and it outputs -9v. from what i've heard though it doesnt' provide a very clean output so if you need a precision -9v, you should output something like -12v and then use a 79L09 regulator to regulate it down to a clean -9v.

Chemelec's way would be much simplier unless, of course, you are powering a pace maker.

so like I need 2-12 volt batteries to run a dual rail op amp in a car. Hmmm seems easy?? I rather find a IC that can switch polarity wouldn't you.