driving an array

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matelot
 
Posts: 11
Joined: Mon Jul 02, 2012 5:41 pm

driving an array

Post by matelot »

I have been asked to produce an 8x8 matrix for a garden BANNED signal.

I have written a program for an Arduino to run two 595 shift registers, one running the signal into each row of the matrix and one running the signal into each column.

The matrix works but the overall brightness is poor.

If I just boost the output current I will burn leds out when very few are used.

Is there a way of limiting current when few leds are lit in each row and giving me enough power when I light the whole row?

Thanks.

Agent_24
 
Posts: 87
Joined: Thu Feb 23, 2012 6:08 pm

Re: driving an array

Post by Agent_24 »

If you are driving the LEDs directly from the shift registers that is probably why they are dim, the shift register itself can't source a huge amount of current. Also I believe the frequency you scan the display at can change the brightness too.

To solve the problem of varying brightness for varying numbers of LEDs you need to run them with a constant-current driver.

Post a schematic of your circuit and the Arduino code etc will help

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