I am thinking of how to put together a large countdown timer. I have it working fine with one of those four digits in one block type displays, using a 74HC595 chip.
Now the challenge is that the big ones take 9 volts and thus cannot be powered by the Arduino. See:Digits on eBay
So, I am slightly baffled on where do I supply the 9V?
Should I plug it in the Arduino and branch out voltage and ground wires before the plug to gain common ground?
Attached is a copy of the code.
I am probably just as confused
Each large 7 segment display has its own TPIC6B595 wired as in the pic for one digit.
Arduino provides four clock and four latch wires in parallel,
and I assumed four data lines.
This is somewhat tough for me to see how to code it.
Every bit of information helps, so thank you for your time and effort.