8 by 8 Red Green Display - display red and green

Hi everyone, I just bought a set of 8 by 8 LED matrix from Active Surplus http://www.activesurplus.com It a board containing 8 - 8-by-8 LED matrix for $10 ca. After de-soldering the parts, end test and investigate the LED matrix ( for pins, voltages, current, rows , colums ) I discover that if you want to display red but not green, display green not red. ( red and green can not be at the same time ) :~

My question is how can I do to display red or green using logic gates or multiplexer or de-multiplexer ?

Here a basic diagram of one cell.

By the way, how do I insert a picture, I try and it is not working. I did select "insert image" and type the location of my picture and not working. :(

Select Reply below, than Additional Options, then Browse to your picture & upload it.

Or, upload it to a site and post the link using this format (with the spaces) [ img ] http : // www. website. com / your_picture. img [/ img ] for example

www.dipmicro.com is a good source for parts when you work out what you need.

Here again a picture of my diagram…I know it is not the best… :blush:

It work… I think I better draw a better schematic. Thank Crossroads

Anyway here a picture of the parts and my bench…Sorry for the mess.

www.dipmicro.com is a good source for parts when you work out what you need.

Thanks again CrossRoads for the new store for me to order parts. Being close mean orders arriving quiclly. I usully drive to electronics store in Toronto to get my parts. Always shop locally.

Any part numbers on those? The diagram is not readable.

I have to re-done the diagram. Sorry about that. Later today if I have the time.

CrossRoads - Here a new and improve diagram. It include a schematic of a cell of the matrix, data about the matrix and the pinouts. I investigated this part. :wink:

I will need 24 pins to control the matrix, so the solution is to use 74595 - Serial to Parallel - 8 bits. 3 chips to be exact. I will have to learn to use a 74595 with Ardiuno, and use what I lean to display the matrix. Unless it exist a better way.

Excellent control logic. Next you need to find a way to resize your pictures to about 1/4 of what you posted. The"thumbnail" is too small to make out the details, the enlarged is so big it is very difficult (impossible) to use the scroll bars to view it all. (I make the same mistake sometimes as well). The PNP & NPN transisters & current limit resisters are dead on.

Thank for the compliment. I have a “standart” way to display led’s. I don’t want to overload the Ardiuno or the control chips. The transistors will be selected depending of the curent and power through them. I wil use an electronic circuit simulation to find that info. Because one transitor should be able to handle 8 LED on at the same time. I am not sure a 2N3904 or 2N3906 will handle the current ( they are max about 200 mA ) Heh , may be it is possible - 10 mA * 8 = 80 mA

About my pictures, well it work if I download the pictures and display the pictures using a photo program or Explorer. I scan the schematic and save as a picture. I try not to exceed 1 M size.