Is more cheap with the 74HC595

So I will use 8 74HC595 and 26 transistors an resistors

 

Can anyone give me a good buffer scheme to use on this project?

 

I start soldering the LED's

But I still have a question: if i will light only a LED , why I will need the transistors?

 

I have not followed this thread for a while. But to be general. A chip has maximum current for each IO pin. But also for the total current. So if you have a 40 pins PIC. It is no problem to control a few LEDs. But you will not be able to use all the ports to turn LEDs on at the same time. Say you will have 35 pins available as output pins. using 20 mA pr LED. Will give a total current of 0.7A to much for a PIC

 

I understand that, but I have been advised to control the hole matrix by turning on only one led and surfing the matrix at very hight speed. In this case my logic says that I don't need transistors.

So how is easier to write the code to control the matrix? By turning only one led at a time or by turning on more led's?

 

I finish all the led's connection and solder all the HC595 wire.
The problem is that if I want to light a led(simple, without the HC595) , in many cases other 1-7 will light as well(with a more week brightness of course ).
I measure with a multimeter and i have no surtcircuit.
What is then the problem or how I can detect it?

Sorry for the poor quality of the photo, I will make others on a better quality.

 

did you ever get this project working ? , I think you should have started with fewer LEDs , I'm playing around with something like this right now

 

The TS was last heard from three years ago. I don't think he is listening anymore.
Start a new thread if you want some follow up.

 

yeah I thought as much