5V Linear Regulator

[Private Reid]

Enerywhere i go to buy a regulator, the person serving me askes if i would like it to be a negative or positive regulator?!

is there a difference?

which one should i buy?

5v negitive

5v positive

[ALZ]

Hi Private Reid:  Yes there is a difference. Not to be a smart ass but I don't know what you are builting so I don't which one you need. What it means is if your ground is negative and the other power rail is positive then that's a  positive  regulator. If your ground is  positive and the other power rail negative then it's negative regulator.

[Afroman]

The vast majority of the time you want a positive 5V regulator.
For example, going from a 9.6V battery pack down to 5V to power a microcontroller will require a positive 5V regulator, such as the classic LM7805.

Negative regulators are generally only used for creating regulated negative rails for use with certain amplifier circuits.