Multiple led

I want to make a led circuit of around 56 leds revolving. 8 sets of 7 LED's with only one set on at a time. Kinda like a police light but powered by a computer PSU molex or multiple molex connector if necessary. The LED's that I am looking at have a continous forward current of 20mA.

ok, and?

So are you going to rotate it all or are you going to make slip rings:-

I just want the lights to turn and off to look like it is rotating. So one set of seven will be light at a time. Like the cylons eye but in a circle not back and forth.

So the LEDs are not physically revolving just the lit lights?

Like the cylons eye

Can you post a link?

Then all you need is a transistor on eight digital outputs, one for each set of LED's. You then just sequence through the digital outputs in code.

20mA per LED x 7 = 140mA.. more than you can really drive from the pin directly, but well within the power switching capacity of the cheapest of NPN switching transistors, like 2N2222 or 2N3904. You can get a pack of em at any electronics store, even Radio Shack, for a buck or two for a handful. Put a 1k resistor between the output pin and the base of the transistor, that's fine for current limiting while still giving plenty to drive the transistor to saturation, making it a switch. Now just wire your LED's and voltage matching resistor to the collector and connect the emitter to ground. Since you are only switching one set on at a time, you should be fine drawing the power off the 5v rail and not need external power. If you plan to light more than two sets at once however, I would recommend tapping the Vin (9v) line and adding another 7805 (or other) regulator to supply just your LED's. With all the led's lit, you'd be drawing well over an ampere, which would likely cook the 7805 regulator on the arduino.

The rest is just your code switching those pins off and on in whatever pattern or timing you desire..

How about this - get a boost regulator, one of the variable output kind, and wire the LEDs in series with a resistor and transister per set - then only need to switch 20mA on at a time. Something like this, set for 15V or so (play around, see what your 7 LEDs need). http://www.pololu.com/catalog/product/799 Or wire the LEDs as 3 & 4 in series from 9V, with the transistor turning both columns.

I use this same part to create 12V to drive 2 of these cards, with a 7406 (open collector output) as the drive transistor.