using 555 and 4017 to cycle 7 LED's

Thread Starter

Tony Spence

Joined Dec 20, 2013
64
Could you draw the timing sequence of leds, it may more clear to describe what you really want.
I want it to go 7654321 and repeat with one LED on per pulse

but its doing this and the last one is constantly on until all off
7 1
6 1
5 1
4 1
3 1
2 1
all off
and then repeats

does this help describe it better
 

ScottWang

Joined Aug 23, 2012
7,397
I want it to go 7654321 and repeat with one LED on per pulse

but its doing this and the last one is constantly on until all off
7 1
6 1
5 1
4 1
3 1
2 1
all off
and then repeats

does this help describe it better
Your two described there were little different.
I will provide an idea and you check it if anything needs to modify.

The numbers from 7...1, about this you can reverse the sequence of leds and labeling as 1→7, 2→6, 3→5, 4→4, 5→3, 6→2, 7→1, and if you want any led to keep at lighting then you can using 7 1N4148 connecting to a resistor and connecting to the base of npn bjt, e connecting to gnd, c connecting to a current limits resistor and to the negative of led, the positive of led connecting to 9V.
 

wayneh

Joined Sep 9, 2010
17,496
I want it to go 7654321 and repeat with one LED on per pulse

but its doing this and the last one is constantly on until all off
7 1
6 1
5 1
4 1
3 1
2 1
all off
and then repeats
So if LED #1 (using your numbering here, which is opposite to the schematic, right?) were removed, you would say this is working fine for what you want, less the #1 LED?
Does your table indicate that LED #1 is on all the time except briefly when all are off? You must have it miswired to the wrong pin of the 4017. Check the leads of the LED to make sure they have not laid over onto the wrong pin. A photo may also help us see something you have missed.
 

Thread Starter

Tony Spence

Joined Dec 20, 2013
64
Sounds like number 1 led is wired backwards.
I turned the 1
So if LED #1 (using your numbering here, which is opposite to the schematic, right?) were removed, you would say this is working fine for what you want, less the #1 LED?
Does your table indicate that LED #1 is on all the time except briefly when all are off? You must have it miswired to the wrong pin of the 4017. Check the leads of the LED to make sure they have not laid over onto the wrong pin. A photo may also help us see something you have missed.
is it possible that an LED could be manufactured backwards
 

wayneh

Joined Sep 9, 2010
17,496
Try resetting on 8 instead of 7. I think you're getting a near simultaneous clock and reset, skipping over "0", your LED #1
 

Thread Starter

Tony Spence

Joined Dec 20, 2013
64
Try resetting on 8 instead of 7. I think you're getting a near simultaneous clock and reset, skipping over "0", your LED #1
i connected the reset to pin 9 and added an led but i still got the same problem both of the LEDs stay lit until all off then they blink and stay on again kind of like a count down to the led thats on then they all go off for a second
 
Top