running leds

Thread Starter

eldadoh

Joined May 2, 2014
23
I used 3 jkff and 4-16 decoder to make 16 running leds . they work like this :
*
-*
--*
---*
----*
-----*
------*
-------*
--------*

i want they run like :
1
12
123
1234
12345
123456
1234567
12345678

i want to do this with shift register? can you tell me how does it work and where I need to connect the shift register .? thanks
 

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Last edited:

ericgibbs

Joined Jan 29, 2010
18,766
hi,
Are you using a 555 timer or something similar to clock the 3 * F/F's.?

Its is possible to use shift registers to get the sequence that you have posted, but what do want to happen next when all the LED's are lit.?
E
 

Thread Starter

eldadoh

Joined May 2, 2014
23
hi I add picture of my circle .
I want that after all the leds are on it starts again from the first led to the first+second and go on

1
12
123
1234
12345
123456
1234567
12345678
1
12
123
1234..
 

ericgibbs

Joined Jan 29, 2010
18,766
OK,
Which types of shift registers can you purchase at your location.?

I know that its not always possible to get all types locally.

E
 

ericgibbs

Joined Jan 29, 2010
18,766
we got on lab 74LS91N
hi,
The 74LS91 Shift Register is a Serial in , Serial Out type, it is not suitable for your project.

A 74LS164 Serial In, Parallel Out is the shift register you need for 8 LED's and you can also connect two or more in series to light more LED's.

E
 

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WBahn

Joined Mar 31, 2012
29,978
You may have some difficulty getting the restart behavior you want because you need to clear the contents of the shift register except for one bit. I haven't looked at the data sheet but if you've got a parallel load then you are fine.
 
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