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16*56 Dot matrix soruce and sinking current issues
Can you post a schematic of your circuit? It's hard to troubleshoot the problem without it.
Tuesday, 10 April 2012 - 15:07
Creating a 8x8 LED matrix with 2 shift registers?
Oops. Looks like we had a server failure that took down the images. Let me see if I can figure out how to upload the most recent one here.
Monday, 9 April 2012 - 17:55
16*56 Dot matrix soruce and sinking current issues
You are going to need drivers of some sort on the columns. While the 74HC595 can sink up to 35mA on any one pin, there's another limit of 70mA total for all pins. This would limit...
Monday, 9 April 2012 - 17:41
Creating a 8x8 LED matrix with 2 shift registers?
mondalaci, that looks about right.
Wednesday, 4 April 2012 - 17:17
16*56 Dot matrix soruce and sinking current issues
You might want to take a look at the discussions on this thread: https://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=118682
Wednesday, 4 April 2012 - 17:10
Creating a 8x8 LED matrix with 2 shift registers?
mondalaci, Looking through the data sheet for the 74HC595, I can't find any reference to Default values when power is first applied to the chip. Given that lack, and the fact...
Monday, 2 April 2012 - 18:56
Creating a 8x8 LED matrix with 2 shift registers?
Jan_dc, you're right, I'd missed that little point about the total VCC current. Mondalaci, you have the IC total right, just don't forget the eight current limit resistors. If you...
Wednesday, 28 March 2012 - 15:12
Creating a 8x8 LED matrix with 2 shift registers?
mondalaci, the first idea was based on an assumed average current of 20mA per LED. Because of the multiplexing, This means a peak current of 160mA with a 1/8 duty cycle....
Monday, 26 March 2012 - 20:54
Creating a 8x8 LED matrix with 2 shift registers?
Here's what I would use as a circuit for the display. It uses 3 ICs and eight resistors. Only three output pins are needed from the CPU. To use it, shift out eight bits with only...
Friday, 23 March 2012 - 15:07
Creating a 8x8 LED matrix with 2 shift registers?
jan_dc, your circuit can't work with all the LEDs separately controlled. In your circuit, turning on any single LED requires turning on both the row and column transistors for...
Friday, 23 March 2012 - 14:47
Is this real?
Those inductive pickups work on magnetic materials, not conductive materials. Bringing magnetic material into a magnetic field will reduce the reluctance of the magnetic circuit,...
Thursday, 22 March 2012 - 21:21
Sense doorbell being pressed
How much current is drawn by the chime when it's operating? If it's relatively small, put a small, low voltage lightbulb in series with the chime, and put the bulb inside a light...
Thursday, 22 March 2012 - 18:07

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