After making a 8X10 matrix a lot of people asked me about expanding the matrix to some thing bigger, and some wanted to write stuff to the matrix via a PC, so one day I looked at a pile of LEDs that I had leftover from a LED cube projected and I decided to make a bigger matrix with all the things people wanted.
So what are you waiting for? Get those LEDs out and heat up your soldering iron because we are about to make a 24X6 LED matrix!
So you will need the basic set of tools for this project : a soldering iron, some solder wire, a cutter, a needle nosed plier, some wire, wire striper, and some DE soldering tools if you need them.
For the matrix you will:
1. 144 LEDs
2. 24 resistors( The value is determent by the type of LEDs, in my case 91 ohm)
3. 4017 decade counter
4. 6 1KOhm resistors
5. 6 2N3904 transistors
6. A long Per board
8. 3 x 74HC595 shift register
10. some pin headers
The tricky behind the display is multiplexing and the idea is the same as with the 8×10 LED matrix: It is basically a way to split information in to little peace’s and send it one by one.
this way you can save a lot of pins on the Arduino and keep your program quite simple.
Now this time we have 3 shift registers which multiply the number of outputs and save lots of arduino pins.
Each shift register has 8 outputs and you only need 3 arduino pins to control almost an limited numbers of shift registers.
We also use the 4017 decade counter to scan the rows, and you can scan up to 10 rows with it because you have only 10 outputs but to control it you need only 2 pins.
The 4017 is a very useful chip and it’s a good idea to know how to work with it(http://www.doctronics.co.uk/4017.htm)
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