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Topic: Led Matrix 24x10 (Read 552 times) previous topic - next topic

samjack

Hello,

I want to make a led matrix of 10 lines and 24 columns.
But i have a question about powering the leds.

I created a 5x5 matrix, but when 1 line of 5leds is on, the leds are dimmed

The lines are powered with a 74hc595 and the columns with another 74hc595 with on each output pin a resistor and NPN for the ground.

I don't want this problem in my 10x24 matrix.
what must i be used for powering up the matrix?

each led must have the full brightness (20mA)
i want to switch 480mA, but the 74HC595 connat and tpic6B595 is only sink.

who can help me?

my local parts shop say to use a 74LS595, but see no difference

What about a 4017 decade counter for sinking?

CrossRoads

74HC595 controlling PNP transistors to source current into anodes, 74HC595 controlling ULN2803 to sink current from cathode columns.
200mA to sink per column.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Grumpy_Mike

Depending on the way you wire it up will depend on the software you need to multiplex it.
http://www.thebox.myzen.co.uk/Workshop/LED_Matrix.html


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