# 4017 delay?

Discussion in 'General Electronics Chat' started by MikeA, Jun 29, 2013.

1. ### MikeA Thread Starter Member

Jan 20, 2013
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I'm trying to insert a delay after the typical 4017 cycle. Say I have a 555 timing the 4017 at 10hz, so each output will have a period of 100ms. I'd like for the 4017 to go through one of its cycles, then pause for say 1 second. Then repeat the cycle with 100ms period, pause for 1 second again, and on and on. Any ideas how to accomplish that?

2. ### GopherT AAC Fanatic!

Nov 23, 2012
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I am not exactly sure what you mean. Could you please make a graph of what you want. X-axis is time. Make three off-set signals moving across the graph (555 signal, 0.1 sec, 1 sec)

3. ### Ron H AAC Fanatic!

Apr 14, 2005
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I can show you how to do it, as long as you can tolerate the 10th stage being on during the pause.The 4017 does not contain logic that allows all stages to be off.

4. ### MikeA Thread Starter Member

Jan 20, 2013
125
17
Ron H, sure, that would be acceptable. So if it's 10hz, it will be...

100ms, 100ms, 100ms, 100ms, 100ms, 100ms, 100ms, 100ms, 100ms, 1000ms (on)?

5. ### MikeA Thread Starter Member

Jan 20, 2013
125
17
Something like this....
on (100ms), off(100ms), on(100ms), on (100ms), off(100ms), on(100ms), on (100ms), off(100ms), on(100ms), off(100ms), pause(1000ms)...and repeat...

6. ### Ron H AAC Fanatic!

Apr 14, 2005
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That doesn't make sense to me.
A timing diagram, showing all 10 outputs, would be nice.

7. ### GopherT AAC Fanatic!

Nov 23, 2012
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I think I understand (assuming you meant on/off every 0.1 sec). Then off for one second.

I don't think I have ever submitted a hand drawn schematic before.

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8. ### MikeA Thread Starter Member

Jan 20, 2013
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Like this. X-axis is milliseconds, in 100ms increments. Y-axis is 1 = on, 0 = off.

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9. ### Ron H AAC Fanatic!

Apr 14, 2005
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A 4017 has 10 outputs. Is that supposed to represent all of them, or only one?

10. ### GopherT AAC Fanatic!

Nov 23, 2012
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MikeA,
Ok, do what I suggested in my drawing but on 4017A, connect pins 2, 4, 5, 6, 8 to ground with a 10k resistor. You will get your pattern from pionts 1, 3, 7 and 9 (connected as shown in my previous hand-drawn schematic).
The OUTPUT you need comes from the AND gate in my drawing.

RON,
It looks like he only wants one output but he has a CD4017 to work with.

11. ### absf Senior Member

Dec 29, 2010
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The way I did it is similar to GopherT . But the 1S delay is slightly shorter and the first pulse is about 70% of 100mS. I used a 4011 Quad NAND, but 3 of them are used as inverters.

Here is the schematic and captured scope wave form.

Allen

 U2 "MR" pin should be grounded.

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• ###### 4017 delay scope.PNG
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Last edited: Jun 29, 2013

Apr 27, 2013
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13. ### LDC3 Active Member

Apr 27, 2013
920
160
absf,
There is a problem with your circuit. The CO line is low when any of the last five lines is high, not when the last line goes high (or after) as the circuit expects. See page 7 here.

14. ### GopherT AAC Fanatic!

Nov 23, 2012
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Pin 0 should connect to the input of CD4017(B) as shown in the schematic.

15. ### absf Senior Member

Dec 29, 2010
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U3 is not enabled until U2 Q9 is high. Even though the clock pulses kept coming in. Q0 of U3 would be stuck in high until U2 has finished doing its job. I only need the first o/p to be high to work.

I have simulated the circuit and it works. Take a look at the wave form from the O-scope?

Allen

16. ### MikeA Thread Starter Member

Jan 20, 2013
125
17
Thanks guys. Seems the 4017 is more trouble than it's worth, especially since I want the outputs to be independent. I might as well get a small PIC to blink some LEDs. It will offer much better timing control.

17. ### LDC3 Active Member

Apr 27, 2013
920
160
You don't have Q0 on U3 connected to anything. You have CO connected to the NAND gate.

18. ### absf Senior Member

Dec 29, 2010
1,493
373
On a closer look at my schematics, I found bigger mistakes and wonders how it simulates successfully. Besides the CO (carry out) is wrongly used, I cannot understand how the clock pulses can get through U4C when Q9 of U2 was high all the time and it mysteriously goes low on the 18th pulse.

I need to breadboard the circuit when I have more time to confirm if my simulator is having some library component error on the 4017. But anyway the OP has abandoned the use of discrete logic chip and opt to use a small mcu to implement his circuit,, so I see there's no big hurry to make my circuit to work.

I used excel to enter the event table for the 2 4017 inputs and output just for someone who is interested to tackle the problem.

cheers

Allen

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19. ### LDC3 Active Member

Apr 27, 2013
920
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Allen,
There is a mistake in your table for U2, the Enable should be high for clock count 9 (or is it 10) through 16 to hold the counter from advancing.