I'll make a different suggestion:
Get four 74HC125 buffers to drive the LEDs, and multiplex them using the output enable pins.

 

I'll make a different suggestion:
Get four 74HC125 buffers to drive the LEDs, and multiplex them using the output enable pins.

is this not what I'm trying to do? My task would then require 3 of these chips, " Sinks or sources 4mA at VCC = 4.5V " and Schmitt trigger

 

hi K,
What are the 3 Enable lines connected too.?
E

 

Apologies - I meant the 74AC version - that will drive 24mA

 

hi K,
What are the 3 Enable lines connected too.?
E

The pins that would have driven the PNP transistors in the previous idea.

 

hi K,
What are the 3 Enable lines connected too.?
E

arduino digital outputs, 12 numbers, 12 bit display, infinite possibilities

 

arduino digital outputs, 12 numbers, 12 bit display, infinite possibilities

hi K,
I would like to help, perhaps if you explained what is the purpose of project, we could suggest better alternatives.
E

 

hi K,
I would like to help, perhaps if you explained what is the purpose of project, we could suggest better alternatives.
E

The goal is of this project is to make an Arduino real time clock with an 8 bit display, whatever leftover space left in the ROM will be fun LED patterns. Then I plan to make a minamal arduino with just the atmega328 chip as a standalone LED driver. This project is about learning arduino not the best LEDs ever haha. From there I can revise how the LEDs are driven. I have a ton of junk and buying more costing money, who has time for that?

 

I have a ton of junk and buying more costing money, who has time for that?

I thought that was what we all did. I've still got a few dial-up modems, I doubt they'll ever "come in handy" as I have an internet telephone.

 

There aren't 36 pins available... So...?

Unless the Arduino is a Mega. Then there’s over 50 pins.