It keeps coming up, for for a 25 position sequencer this is the simplest solution. You could use a shift register, but it would take about 1.5X the chips. The cost of the 4017 is very low too (as well as being very available), and it can be expanded pretty much indefinitely. I've seen other designs. Parts availability is the only reason I don't go with Wookie's suggested driver too. IMO DIPs are harder to work with than transistors, especially on PCBs, the base resistors allow for easier routing.

For 10 outputs nothing beats the 4017, it is the simplest solution.

As for the random start up Wookie mentioned, this could be handled with a pulse on reset, which could be done with a simple RC circuit. I'm glad he mentioned it though, because it is so easy to deal with and design for.

OK, I'll come up with a new design, and make a PCB layout for it. When I do it will be on its own thread, and I'll add it to the LED article as a resource, probably a addendum.

 

Hi there,
I know you guys know more about this than me, but i think there might be a simpler solution for our OP
If the OP doesn't mind more than one LED lit up at one time, the 4017's could simply be daisy chained using the pin 12 carryouts, with the LED's going right from the outputs to ground with, say, a 330Ω resistor for maybe each group of 10?

This idea won't work due to the way the pin 12 carry out works; it's low from when OUT 0 to OUT 4 are active (high), and high from when OUT 5 to OUT 9 are active (high).

Have a look at an OnSemi MC14017B datasheet for the timing diagram.

 

Oh, wow, i knew that, i use that function all the time...
this is why i dont usually post
*head slam on table
BUT, if you had the right reset pull up on it, you could run the 555 out to each of them and they would be synchronized for the same effect, right?

 

What you describe is not grounding pin 5 (which you normally wouldn't want to do) but providing a more stable threshold voltage.

Whatever "glitches" there are during start-up should sort themselves out after a couple of clock pulses.

OK.

I've read somewhere that if the 555 got triggered when the power was applied, you could set a cap from pin 5 to ground.

Now I know why.

 

OK, here is the design I'm thinking of for the PCB, with power up reset included. I'm not positive about the reset circuit, but I'm pretty sure it will work. My thought is you can always leave parts off.

 

Oh, wow, i knew that, i use that function all the time...
this is why i dont usually post
*head slam on table
BUT, if you had the right reset pull up on it, you could run the 555 out to each of them and they would be synchronized for the same effect, right?

I am not sure what you mean by that since you didn't post a schematic or timing diagram, but offhand I'll have to say no, it wouldn't work.

If you can make your proposed circuit work consistently, then post it.

 

thank you very much sir!.can i connect more than 5 4017ic?? to make more running LEDs?..

You only need to increase the drive.

Most Christmas light "chasers" use 4 or 5 LED sets, and repeat the 1-2-3-4-5 pattern. Using 2 LEDs makes a toggle effect, 3 LEDs makes a bit of a chaser effect, but can still be noticed. Beyond that, if moving quickly, the whole string will appear to be "running", using only 6 wires (1 for each LED, 1 for ground).

 

You only need to increase the drive.

Most Christmas light "chasers" use 4 or 5 LED sets, and repeat the 1-2-3-4-5 pattern. Using 2 LEDs makes a toggle effect, 3 LEDs makes a bit of a chaser effect, but can still be noticed. Beyond that, if moving quickly, the whole string will appear to be "running", using only 6 wires (1 for each LED, 1 for ground).

sorry sir, but what do mean by drive?.. and how can i boost the current to the 5 or more LEDs connect in series??..

 

Boosting the number of LEDs per transistor is easy. How many sequences you want? You will note the one above is 25 LEDs, it is easy to reduce that number, less than 18 sequences only needs 2 4017s, and less than 11 only needs one 4017.

It is important to distinguish between number of sequences and number of LEDs per sequence.

A suggestion, do a quick sketch of the final display (LEDs in position on a board or whatever), number the sequences, and post it.

Currently I'm in the middle of redrawing the schematic diagram in Express, a PCB utility program. I also corrected some schematic errors in post #25

 

BTW, did you read Chapters 1 and 2 of LEDs, 555s, Flashers, and Light Chasers? It will really help in explaining what you can and can not do.

If you do decide you want more LEDs per sequence then some modifications on the schematics will be required. They are minor, mostly part value changes, but needed. As is the LEDs are designed for 20ma each.

 

i try to make letters that are running.. hmmm i think 20 LEDs per sequence., how to boost?

 

And how many sequences?

Are you talking a marque display? I'm not sure how you would get there from a sequencer. This is normally done via µC due to the complexity. However, I could be misunderstanding what your saying.

 

6 sequence... (1) z - 20 LEDs, (2) a - 20 LEDs, (3) c - 20 LEDs, (4) k - 20 LEDs, (5) n - 20 LEDs, (6) i - 20 LEDs.

yes!.. that is the display.. sorry for misunderstanding, im just a newbie of world of electronics,,

 

Heh, you can get by with one 4017 then, not the 25 sequencer I posted.

Have you read the chapters 1 and 2 I recommended? Did you understand them?

The reason I ask is there is another chapter devoted to driving LEDs like you are wanting to do. That would be Chapter 10 -Transistor Drivers.

Chapter 11 -Making Patterns Figure 11.1 covers how to sequence specific LEDs.

Chapter 9 - Light Chasers covers some of the theory.

 

ahh... so it uses LM317 to supply curretnts to all LEDs.. am i right?

 

I'm splitting off another thread concerning the PCB and work that has been done.

25 LED Open Ended Sequencer

To the OP: Don't worry, I'll keep up with you on this thread. None of the work applies for your project, and it is bad manners to hijack someone else thread. So I will pick up the other project and help you with yours as needed.

 

ahh... so it uses LM317 to supply curretnts to all LEDs.. am i right?

I suspect you are talking about Chapter 9, Figure 9.1. The driver doesn't really apply, you need to refer to Chapter 10 for that.

What Chapter 9 does do is explain how you can take a 10 step sequencer and bring it down to a lower value (say, 6 sequences) with a single wire.

I'll probably help you design a specific circuit, but I need your power supply voltage and the color of the LEDs

I've asked before, but have you read Chapter 1 and 2? There are key concepts there, like why I need the power supply voltage and the color of the LEDs. Too much info is always better than too little.

I will also need how you are sequencing the LEDs (Chapter 11 cover that).

Bed time for me, I'll pick this up again tomorrow.

 

i can use a pull up resistor,.

 

There is a shop that somebody linked on here that has pre-etched "blank" matrix PC Boards, all that needs to be done is add surface mount LEDs to make the pattern you'd like (any letter or symbol), and connect it to (enough) power.

I totally forgot the site, though.

However, the end product would be "N" turning on, then off, then "I" turning on, then off, then "C" turning on then off, then "K" turning on, then off (well, whatever letters you'd like, actually).

If you wanted more effects than that, it gets a little more difficult. However, since you were mentioning drawing letters, I thought I'd mention those PC Boards, they would make the assembly part of the project very easy.

 

Like I said earlier, I would be glad to draw a schematic, but I need a basic layout of the LEDs (and their colors). Give a guy a clue?