# 9V battery to +-15V

#### nils

Joined Oct 30, 2006
3
Hi all!
i wonder if some of you could help me with a question i have..
I need to convert a 9V battery to +-15V. Is that possible?
Or do i need two 9v batteries to be able to convert each of them to + and -??
Is it anway possible to convert 9V to 15V at all???

/nils

Joined Jan 10, 2006
614
Yes, it is possible. The best method would probably be to convert the 9 volts to a form of high frequency AC, feed that into the primary of a suitable transformer and rectifying the outputs for your + and - rails.
There are also transformerless methods as well.
What sort of current is required for the +15 and -15 rails..?

#### nils

Joined Oct 30, 2006
3
i need +-15 DC to supply an OpAmp.. i'm not sure i really need it to be 15V but it's what the OP will work best with.. (if i got it right..)
thanx a lot for the quick answer.. unfortunatley i have to admit i'm really new to this.. it would be great if you could make it a little.. mmhmm.. easier..
but don't mind if u think i'm askng too much. a complicated answer is better than no answer att all! i'll figure it out in some way..

#### hgmjr

Joined Jan 28, 2005
9,029
Greetings nils,

One simple approach to your supply requirements would be to use two 9 volt batteries.

One for the negative voltage and one for the positive voltage. That would give you a +/-9 volt supply quickly.

hgmjr

#### nils

Joined Oct 30, 2006
3
well i actually thought about that. i just wonder if +-9V would be enough (i think i just have to try it out..) and if it's just as simple as that.. i mean.. is it really possible to connect +9V to the -Vin and just pretending it's -? or do i have to change its phase to really become -9V??
i know.. it's maybe that most stupid question you ever read.. but i really don't know how it works!
thanx anyway!!!!

#### hgmjr

Joined Jan 28, 2005
9,029
All you will need to do is connect the two batteries in series so that you have 18V and then use the point where the negative and positive terminals are connected together as your ground reference.

hgmjr

#### mrmeval

Joined Jun 30, 2006
833
Which op-amp?