# 4017 Counter LEDs to stay on

#### Colin55

Joined Aug 27, 2015
519
You are much better off with a 16 output shift register

#### hp1729

Joined Nov 23, 2015
2,304

Using an Arduino to control a dozen 4017 - 555 circuits to sequence
320 LEDs. The problem is the 4017 turns on LED 1 then turns it off
and then turns on LED 2. The project wants to turn on LED 1 and
leave it on and then turn on LED 2 and leave LED 2 on, then
turn on LED 3 etc.

Maybe the 4017 won't do this but does any one know if it will
and if so how?

Thanks.

Allen in Dallas

Using an Arduino to control a dozen 4017 - 555 circuits to sequence
320 LEDs. The problem is the 4017 turns on LED 1 then turns it off
and then turns on LED 2. The project wants to turn on LED 1 and
leave it on and then turn on LED 2 and leave LED 2 on, then
turn on LED 3 etc.

Maybe the 4017 won't do this but does any one know if it will
and if so how?

Thanks.

Allen in Dallas
Shift register (74xx595 or 4094).

#### Colin55

Joined Aug 27, 2015
519

#### Wendy

Joined Mar 24, 2008
21,938
That is a bit pricey. Shift registers are pretty cheap. If we ever hear back from the TS I'll look one up.

#### Colin55

Joined Aug 27, 2015
519
That's 30cents each

#### Wendy

Joined Mar 24, 2008
21,938
My bad, missed the 50 pc quantity

#### Colin55

Joined Aug 27, 2015
519
No. They are $15.60 each . Buy 50 of them and you can pay the Chinese$750 and they will be more than happy.

#### ISB123

Joined May 21, 2014
1,238
Colin you sure do like sarcasm.

#### dannyf

Joined Sep 13, 2015
2,197
A simpler approach is to OR the output. For example, the first led would be connected to q9..0 through diodes so if any of the output is high, that led is on. The second diode would be connected to q9..1 through diodes, .... I'm assuming that you want 10 digit output here.

#### Colin55

Joined Aug 27, 2015
519
How are you going to drive 10 LEDs from one output ????????

#### AnalogKid

Joined Aug 1, 2013
8,315
I'm assuming that you want 10 digit output here.
320 outputs, post #1.

#### Bernard

Joined Aug 7, 2008
5,400
From way back a 4017 "stacker".developed for Oxbow-Rene.
.

#### hp1729

Joined Nov 23, 2015
2,304
That's not a bad price if you need 50 pieces. $0.31 each. <<< Good buy. 74HC595,$0.89 from Jameco, $79 ea at 30. CD4094 is about$0.45.
74HC595 outputs can drive 20 mA high or low. CD4094 drives less than 1 mA so you still need an LED driver.

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#### ronv

Joined Nov 12, 2008
3,770

#### dannyf

Joined Sep 13, 2015
2,197
4017 "stacker".developed for Oxbow-Rene.
That's equivalent to the OR operations built with diodes. The diode approach is cheaper and more affordable, however.

#### Wendy

Joined Mar 24, 2008
21,938
Actually I mentioned steering diodes, but here is the rub, around 700 diodes, give or take, which is why I also said it was not very practical.

Add 45 or IC, plus 360 LEDs and it adds up quick.

An 8 bit shift register will require 45 IC with very little support circuitry, possibly transistors.

#### dannyf

Joined Sep 13, 2015
2,197
Static display has the advantage of low load on the cpu. However, a binary counter for such a large number of sequential outputs can be astronomical: you can calculate for example the pulses to turn on all 320 LEDs.

I suspect that you will need more computing power than available in the world to do that within a reasonable time frame.

Dynamic display will cut that time down exponentially. But requires considerable computing power as well.

You may want to explore alternatives.

#### Colin55

Joined Aug 27, 2015
519
"However, a binary counter for such a large number of sequential outputs can be astronomical: you can calculate for example the pulses to turn on all 320 LEDs.""

What are you talking about ???????????

Set-up will take less than 1mS

#### panic mode

Joined Oct 10, 2011
1,821
2^320 is about 2.135987e+96. to count this up in 1ms would require some quite serious clock rate....

@Wendy:

AS1130 Data Sheet
MAX6953

they both use multiplexing to drive large count of LEDs through simple serial interface

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#### Wendy

Joined Mar 24, 2008
21,938
This is not a ripple counter, but a Johnson counter. I have not looked at your links yet, but 2^ does not enter into it. With a Johnson counter 360 outputs is 360 counts.

I mentioned the matrix approach to the LED Display, which is multiplexed.

I fixed your links, they weren't working. It would work, but it is not a binary counter, so some programming (which the TS has alluded to) would be required. It would be the simplest of all the approaches though.

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