Help wanted 74HC595 LED sign

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MatteP
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Help wanted 74HC595 LED sign

Post by MatteP » Mon Nov 21, 2016 6:35 pm

I'm new to electronics so I'm sorry if this sounds stupid.

I recently created an LED sign consisting of 97 LED's on a piece of wood that all light up at the same time when I supply it with 3v. I have watched a bunch of videos on electronics and I saw one that used the 74HC595 shift register to light up an LED sign one by one. (https://www.youtube.com/watch?v=Yexp-I8lzP4)

I came up with a circuit using a 555 timer and 13 shift registers (the photo has one too many) but I'm not sure if it will work and I don’t want to blow up all the chips when I plug it in.
Image
My question is: Will this circuit work and is there a more efficient way to do this? Also, does the 555 need 5v as I heard it usually drops a couple of volts? How would I reset it a few seconds after the animation has finished?

Any answers are greatly appreciated.

Garth
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Re: Help wanted 74HC595 LED sign

Post by Garth » Tue Nov 22, 2016 11:21 am

It's a little difficult to tell exactly what you have in the picture; but the general form of using a bunch of 595's for output bits is shown not far from the top of the "circuit potpourri" page of my 6502 primer, at http://wilsonminesco.com/6502primer/pot ... #22_SR_OUT . This diagram is from there:

Image

The main inputs are data (which is daisychained), clock (which goes to all of them), and load (which also goes to all of them). IOW, it's synchronous serial. You shift a new set of data bits in (in your case with 13 of these, it will be 13x8, or 104 bits, shifted with 104 rising clock edges, then hit the "load" line to make the new data show up at the outputs. What do you plan to use to feed the data?
http://WilsonMinesCo.com/ lots of 6502 resources

MatteP
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Re: Help wanted 74HC595 LED sign

Post by MatteP » Tue Nov 22, 2016 7:38 pm

Garth wrote:It's a little difficult to tell exactly what you have in the picture; but the general form of using a bunch of 595's for output bits is shown not far from the top of the "circuit potpourri" page of my 6502 primer, at http://wilsonminesco.com/6502primer/pot ... #22_SR_OUT . This diagram is from there:

Image

The main inputs are data (which is daisychained), clock (which goes to all of them), and load (which also goes to all of them). IOW, it's synchronous serial. You shift a new set of data bits in (in your case with 13 of these, it will be 13x8, or 104 bits, shifted with 104 rising clock edges, then hit the "load" line to make the new data show up at the outputs. What do you plan to use to feed the data?
Yes.I'm sorry the diagram is blurry, the top green wire is the reset one and the yellow one is the clock.Im not at my PC now so I can't post but I'll have to recreate it as I just designed it in breadboard mode. Thank you very much.

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brad
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Re: Help wanted 74HC595 LED sign

Post by brad » Sat Nov 26, 2016 8:22 pm

One question I have is that you need to be entering in at least one logic 1 to begin with so this data can be shifted through the 595 chips. How does this logic 1 get in there to begin with?

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