This LED sequence

[XalaX]

Hi,
i'm a newbie of this forum. I don't understand so much about electronics but i'm good in building my own circuits from projects.

I would like to have help in making this kind of led sequence.
The circuit has to turn on and off about 20 led in this way:

00000000000000000000
00000000000000000001
00000000000000000011
00000000000000000111
00000000000000001111
and so on...
11111111111111111111
01111111111111111111
00111111111111111111
and so on...
00000000000000001111
00000000000000000111
00000000000000000011
00000000000000000001

Thank you for helping me.

Kind regards

PS forgive my bad english, i'm from sicily

 

[Exo]

It would be trivial with a microcontroller like a pic.
If you don't have access to that, i'd make something based on the 4094 CMOS shift register and just shift in ones or zeroes as required.

 

[XalaX]

thank you
but have you got the scheme of the project? or do you know where i can find something like that?
i have no idea about where to start without a project, sorry

 

[Reloadron]

My read is that you want to turn on 20 LEDs in sequence as in count up 1 to 20 and then at 20 start a count down 20 to 1. While each LED turns on in sequence you want the preceeding LEDs to remain lit correct?

PS forgive my bad english, i'm from sicily

Where in Sicily?

CIAO
Ron

 

[vne147]

This question has been asked before. I think the consensus at the time and among the thread contributors was that even though using a micro-controller for this purpose was kind of over kill, it was the simplest way. Here is a thread discussing it.

 

[wkrug]

I think also like Exo.
The simpliest way is, to use a microcontroller.
A normal shift register wouldn'd work, because there is forward and reverse shifting of 20 Bits required.
I'm not shure but i think that function in C-Mos not availible !?
A binary up / down counter with a bit decoder wouldn't work, because the lower bits must stay in 1 Level.

A possible Way is to use 3 EPROMs ( 24Bits ) that will be countet up by a binary counter.
At the end of sequence - All Leds shifted in and out - The Counter must be reseted.
This EPROMs must be progged too, so you can use a microcontroller also.

 

[lilimike]

It seams to me a simple bar graph fed by slowly rising and slowly decreasing voltage would do the job!
Something similar to THIS

Mike

 

[XalaX]

thank you all for answers i really appreciate it !
@mike
in the circuit you linked, is it possible regulate the number of leds on by using the 2 trimmers?
@ron
yes, i want that.
PS i'm from san vito lo capo

 

[XalaX]

thank you for all the informations!
As soon as i build this circuit, i'll post some videos

@Ron:
yes, that is what i want. I'm from san vito lo capo

 

[ronv]

How elegant. An analog solution to a digital problem.

 

[XalaX]

@ lilimike:
can the number of leds on be regulated by the triggers?

 

[lilimike]

The first thing that I had in mind was an analog solution considering what the OP said:

i'm a newbie of this forum. I don't understand so much about electronics but i'm good in building my own circuits from projects.

I figured my suggestion would be simple with no programming involved.

Obviously lots of possibility are available and proposing one should be what this thread is all about shouldn't it?

Mike

 

[lilimike]

The number of LEDs on = the specific voltage you apply.

Mike