78xx Voltage Regulator Pinout


Positive (1amp)

7805       voltage regulator (5v)
7812       voltage regulator (12v)
LM2940...  low dropout regulator (available in 5, 8, 9, 10, 12, 15v versions)

Looking at the front of TO-220 part
(part number facing towards you and metal heat sink tab flat on the table)

pin 1 (left) = input
pin 2 (center) = gnd (also the heat sink tab)
pin 3 (right) = output

 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

Negative (1amp)

7905   (-5v)
7912   (-12v)

Looking at the front of TO-220 part
(part number facing towards you and metal heat sink tab flat on the table)

pin 1 (left) = gnd
pin 2 (center) = input
pin 3 (right) = output



Also see...
http://en.wikipedia.org/wiki/78xx
http://en.wikipedia.org/wiki/TO220