Hi guys.
I am a beginner to electronics and I've been searching the internet for five but i did't find any satisfactory solution to my problem So my last hope is this forum, please help...
I am trying to build a 16x16 single color led matrix, I've connected all 256 leds as shows in the schematic (The schematic is for 8x8 matrix but i built a 16x16 matrix using the same logic)
I have an arduino uno, I can use four 74HC595 shift registers(2 for rows and 2 for columns) to control all the leds. I will lit up one row at a time so a maximum of 16 leds will be powered simultaneously, According to my knowledge arduino cannot provide supply for 16 leds at the same time So i think i have to use an external power supply to power my led matrix But i have no idea how to connect an external power supply to my led matrix and use arduino just to control the leds. So it will be a big help if you can provide me an easy to understand schematic the shows how to connect a power supply to my matrix and control it through arduino and i will be grad if you can explain it to me.
I will lit up one row at a time so a maximum of 16 leds will be powered simultaneously
74HC595 cannot sink (or source) that much current. Use TPICAB595 instead (350mA sink capability) to sink current from common cathode.
8 x 20mA at full brightness (don't forget current limit resistors) = 160mA. 74HC595 has 70mA Absolute Max on VCC pin. I'd go with cd74AC164, 24mA limit on IO pins to source current to the anodes.
Connect external power supply to shift registers to power them. Connect its Gnd to the Arduino Gnd, that's all you need to do.
Hi All,
I am new to Arduino and trying to build 10X16 LED matrix. For Col, 2 shift register 74HC595 can be use but for Rows, we have to use 2 shift register ? If yes please provide the schematic diagram also the algorithm or code for the same.
my email id abhijit2683@gmail.com
Thanks in advance. 
Rgrds
Abhijit
The most practical way to construct your own 16 by 16 matrix, is to use four MAX7219 drivers, each of which operates an eight by eight sub-matrix.
This avoids a lot of problems. Multiplexing only eight lines at a time is more practical in terms of available current and brightness, the MAX7219s not only manage all the current control but perform the multiplexing for you so your code is far simpler. At base, your code is determined in bytes and so the 8 by 8 sub-sections naturally fall to bytes so there is no penalty in coding.
And you still drive the whole matrix with three lines.
As it stands, even if you are using a different matrix assembly, the easiest way to construct it, is to purchase the readily available "kits" on eBay with the MAX7219 and PCB. Some such kits are stackable and can be used with their own LED matrix, the ones that are not stackable are useful if you are for example, using larger matrices or individual LEDs. 
