Am I going to need a buffer for these 595s

Using Arduino LEDs and Multiplexing
1

I have an Arduino that is sending out three digital signals, ground, and +5v to four groups of four 595 shift registers. Each group will control 32 LEDs.

The arduino and the power supply (actually the +5 will be coming from the PS not the arduino) is in a rack, and each bank of LEDs, and their four 595s will be on the other side of a 20' DB-25 cable-so four DB-25 cables total.

Do I need a buffer between the digital pins out of the arduino when each pin splits into four? Can anyone point me to a simple buffer circuit to accomplish this if so?

I am doing this project (except using four 595s instead of two):

Thanks guys!

2

No buffer needed for just four inputs from one arduino. If the number gets above ten then look to use a 74LS04

3

ok, so taking the three digital wires and just splitting each into four wires and shooting those out 20' to the 595s is no problem? Wasn't sure if I'd be dealing with "signal loss" or some such...

4

No problem at all. The number of inputs an output will drive is called the "fan out", it depends on the technology of both input and output but a value of 10 to 20 is typical.