i need that output multiplier thingy for an led matrix for the arduino. i am buying a 5x7 led matrix, and it doesent have enough pins, so i need one of those pin multipliers ic's that will give me more outputs, and i need one from elexp.com becuase that is where i am buying stuff now, i dont know what there called, so i'd be apreciative if some somebody could find one there, and link me up please 
and if possible a link on how to use it, thanks again
-big92+1
You should be able to use this with the arduino. It will take four pins
http://www.acm.uiuc.edu/sigarch/tutorials/ledarray/
Now something like this would be even more complex but...cool...
http://www.elexp.com/opt_2aeg.htm
lol thanks, but i need the little ic thats gives me more digital in's and outs for using an led matrix...
and i'm purchasing the stuff real soon from elexp, so i need it to be from there
cuz i cant run an 8x8 yet alone an 5x7 on the arduino alone, it doesent have enough pins!
and i think that first example you showed me still nedds ic's to be done, or am i wrong?
The MAX7219 is exactly what you want.
Four wires go in, 16 go out. When wired up in a really cool way you get up to a 8x8 grid.
is the ic available at elexp? cuz i dident see it there 
or is it available at a store, like radioshack or a store in upper nj? cuz i dont want to pay shipping on 1 item lol
The ledarray only needs 4 digital pins. Most io expanders will take that many.
I thnk you can expand the io with the 74HC164 though I've not breadboarded it.
part slist for that ledarray all parts are on the website you mentioned
This excludes leds, you should calc the resistor value needed for your leds with +5v and adjust the 220 ohm resistors to the appropriate value.
1 74HC04
1 74HC138
1 74HC164
8 2N2222A
8 1k ohm resistors
4 220 ohm resistors
lol thanks alot man, ill see if i can still add that to my order, but i placed it already becuase i needed to get the order in tonight to get the stuff by this week.
thanks, is there a data sheet, or a tut to do it?
edit, my bad i thought that the schematic was for somthing else...
The IC's are the one from the schematic I posted as are the resistors and transistors. I didn't include the LEDs. If you have four free pins you won't need the io expansion.
By all accounts the max chip is far easier.
ok, ill get the max chip, in time, but the max chip is the one and only chip needed?
and if so do you have a data sheet for it, or a tut?
The max chip is all that you need.
http://www.octopart.com should find you the datasheet or go to dallas' website