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[on:]

I am new to the forum and I want to make a clock with and arduino and an led matrix. I wanted to make the following and change the code:
http://makeprojects.com/Project/PS-2-You+LED+Sign/1069/1#.UOhbMG8bSSo
but it seems that Sure Electronics dosent sell the led matrix anymore. I looked at adafruit.com and came across the following:
https://www.adafruit.com/products/872
but it is more expensive and it is small for a wall clock. Can anyone assist me in what I need or where I can get one of these cheaply.

[Reply #1 on:]

Is this one big enough for you?
http://www.evilmadscientist.com/2007/led-matrix-displays/

[Reply #2 on:]

Is this one big enough for you?
http://www.evilmadscientist.com/2007/led-matrix-displays/

This would be great, perfect size and reasonable price. My only question is how many pins would I need to control this matrix and could I use some kind of a chip to decrease the pins needed without much work.

[Reply #3 on:]

The MAX6953 can control 4 of those 5x7 displays using just 2 IO pins, SCL & SDA

http://www.maximintegrated.com/datasheet/index.mvp/id/3291?ver=F&utm_expid=50713806-2&utm_referrer=http%3A%2F%2Fwww.maximintegrated.com%2Fpst%2Frun.mvp%3Fq%3Dmax6953%26image.x%3D19%26image.y%3D12

[Reply #4 on:]

The MAX6953 can control 4 of those 5x7 displays using just 2 IO pins, SCL & SDA

http://www.maximintegrated.com/datasheet/index.mvp/id/3291?ver=F&utm_expid=50713806-2&utm_referrer=http%3A%2F%2Fwww.maximintegrated.com%2Fpst%2Frun.mvp%3Fq%3Dmax6953%26image.x%3D19%26image.y%3D12

Is there anything cheaper? Maybe it could only control one display would be ok. I cant really imagine spending $25 on a chip that ill probably solder wrong and it does not really look like it would go in a breadboard.

[Reply #5 on:]

Is there anything cheaper?

Same thing on ebay?

How about the MAX7219?

[Reply #6 on:]

How about the MAX7219?

This is a perfect price. I like the led matrixs mentioned earlier but could anyone point me to cheaper ones?

[Reply #7 on:]

Ebay it:
http://www.ebay.ca/sch/i.html?_nkw=led+matrix+MAX7219&_sacat=0&_odkw=.ebay.ca&_osacat=0&_armrs=1

[Reply #8 on:]

Will the MAX7219 work with this matrix I found on ebay?
http://www.ebay.com/itm/150961254444?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

The only reason I would ask is that the chip says common cathode and the matrix says common anode. My strong point is programming not circuits.

[Reply #9 on:]

The MAX7219/MAX7221 are compact, serial input/output
common-cathode display drivers...

http://datasheets.maximintegrated.com/en/ds/MAX7219-MAX7221.pdf

[Reply #10 on:]

The MAX7219/MAX7221 are compact, serial input/output
common-cathode display drivers...

http://datasheets.maximintegrated.com/en/ds/MAX7219-MAX7221.pdf

Thanks, wow my searching skills are sure lacking today. Ill keep looking thanks for everyone's help. Just one last question does anyone have a good beginner (or advanced) circuit book that they could recommend?

[Reply #11 on:]

What is a BOOK?

http://www.electronics-tutorials.ws/index.html

[Reply #12 on:]

MAX7219 is $1.25 here
http://www.dipmicro.com/store/PCB-UNI30H
hard to get much less

$25 is nuts - go to maxim-ic.com and request a sample in DIP footprint. The part works very nice.

There is no difference between common cathode & common anode:

[Reply #13 on:]

What is a BOOK?

http://www.electronics-tutorials.ws/index.html

I think this is going to be my book. Thanks!

$25 is nuts - go to maxim-ic.com and request a sample in DIP footprint. The part works very nice.

This looks great, a free sample is way better than $25.

There is no difference between common cathode & common anode:

Could someone else please clarify this, there is two different answers now.

[Reply #14 on:]

Look at the 8x8 matrix - one is billed as common anode, one as common cathode - which is which?  In both cases, the rows are connected to anodes, and the columns connected to cathodes.

For non-square configurations, like 5x7, you'd want to make sure the 5 anodes made up your rows (driven by the Segment pins), or the 7 anodes if wanted taller rows, with each column having a common cathode (each column driven by a digit pin).