Power 16f84 from serial port thru a Reg.

[Guest_X44]

I recall seeing a schematic with some pins from serial port used to provide power to a voltage regulator, with its regulated output used to power a 16f84.

I measured the serial pins 4 and 7, and gave a reading of about -11V, with respect to pin 1(gnd).

If I reverse it (connect serial pin 4 to gnd of regulator, and serial pin 1 to input of regulator) the regulator output only measured +3.1V.

Anyone who can provide me details on how I should go about it. I'm trying to avoid using an external power supply as I only need to provide power to the 16f84.

How should it then be wired and what Regulator should I use?

[Haplo]

This is a good start:
http://www.hut.fi/Misc/Electronics/circuits/rspower.html