How to freeze CD 4017 (Rain Led Chip)

Thread Starter

MrsssSu

Joined Sep 28, 2021
264
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Dear all, I have successfully simulated a continuous led array that light up consecutively one after another using LT Spice and have even built one on breadboard and it works well. Well, my question is how would you freeze the led and how do we activate the clock inhibit on both the chips? Like for example, this applies all led. When the led is at the 13th led (which is at the second chip), the led freeze when a voltage is applied or even when the led is at 3rd led, it freezes too (which is at the first chip). LT Spice files are attached.


Thank you very much and have a nice day :)
 

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MrChips

Joined Oct 2, 2009
27,727
CD4017 is a 0-9 Johnson counter. The counter will advance once on every input clock pulse.
To stop advancing, inhibit the clock input.
 

Thread Starter

MrsssSu

Joined Sep 28, 2021
264
CD4017 is a 0-9 Johnson counter. The counter will advance once on every input clock pulse.
To stop advancing, inhibit the clock input.
Hi, do I just connect 5V as shown in my diagram with a resistor to the clock inhibit for both ic? :) Because I want to keep it lighting up led consectively one after another for cycles and it will repeat itself and only if I apply a voltage to freeze the led.
 

MrChips

Joined Oct 2, 2009
27,727
Pin-13 of CD4017 is called CLOCK INHIBIT. This pin must be held at GND in order to count.
Set pin-13 to VDD to stop counting.
 

Dodgydave

Joined Jun 22, 2012
10,592
On another note, you only need 1 resistor in the led ground path ( R1 to R10) , as only one will be lit at any time, use a 470 ohms to 1 K
 

Thread Starter

MrsssSu

Joined Sep 28, 2021
264
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Hi all, above is a CD 4017 Rain Led Chip which lights up one led consecutively one after another.

Although led at pin 7 can be freezed by attaching clock_inhibit pin to the pin 7, I would like to freeze led at pin 7 by disabling or grounding the clock signal so that there is no clock signal which means it will freeze. How do I accomplish this using transistors as a switch? :)

LT Spice file is attached below for download


Thank you for reading and have a nice day
 

Attachments

Dodgydave

Joined Jun 22, 2012
10,592
Use a 1N4148 diode to stop the counting, to start again reset the counter, and you only need 1 resistor in the ground path.

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Last edited:

MrChips

Joined Oct 2, 2009
27,727
If you label pin-13 as CLK ENABLE or CE it should have a bar over the label to indicate ACTIVE LOW signal input.

If pin-13 is labelled CLK INHIBIT then there should be no bar to indicate ACTIVE HIGH input.
 

Papabravo

Joined Feb 24, 2006
19,617
#1: Have a look at the datasheet to see if there is a functional block diagram for the chip. Look for the implementation of the CLK_INH* function.

#2 If that proves to be unsuccessful then consider using a logic gate to externally enable or disable the clock. This approach does have some potential problems when you can have an arbitrary relationship between an enable and a clock you can create some difficult to understand problems.

#3 A JK-flip-flop can be used for the clock signal and has an input combination that will hold the present state in a synchronous manner.
 

Thread Starter

MrsssSu

Joined Sep 28, 2021
264
Use a 1N4148 diode to stop the counting, to start again reset the counter, and you only need 1 resistor in the ground path.

View attachment 281409
Hi, thanks for replying. My question is not about resetting, it is about freezing the led by disable clock signal (Make the clock signal to be 0V). Bascially, when pulse reach PIN 7, the led will light up and freezes there, and I actually need to convert that PIN 7 high input signal to disable clock in order to freeze it. So, my requirement would be grounding the clock inhibit signal at all times, because only by altering the clock signal, I can freeze any led on a series of counters where there are many leds as shown in the first diagram. My resistors are considered as leds for me.:)
 

Thread Starter

MrsssSu

Joined Sep 28, 2021
264
If you freeze the counter when pin-7 is activated, how do you get the counter to start counting again?
Well, I would just reset it. My problem is I am trying to freeze it haha. Do you know any solution that can stop the clock when pin 7 goes HIGH so that the PIN 7 will freeze?:)
 

MrChips

Joined Oct 2, 2009
27,727
Well, I would just reset it. My problem is I am trying to freeze it haha. Do you know any solution that can stop the clock when pin 7 goes HIGH so that the PIN 7 will freeze?:)
Yes, take pin-6 (output "Q7") and feed it back into pin-13 (CLK INHIBIT) as shown in post #7.

Note: pin-7 is output "Q3"

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Thread Starter

MrsssSu

Joined Sep 28, 2021
264
Yes, take pin-6 (output "7") and feed it back into pin-13 (CLK INHIBIT) as shown in post #7.

Note: pin-7 is output "3"
Hi yes, this works for if you use 1 CD 4017 IC. However, if you 2 CD4017 IC like in my question, how would you freeze it and if you don't mind download the zip file in my question which I included 2 CD 4017 IC to light leds consecutively from one chip to another chip and simulate the freeze? For example, I would like the led4 (CHIP 1 ) to freeze if i push the same button and also the led 13 (CHIP 2) to freeze if I push the same button too, so I only need 1 button to freeze the led for both chips ? Can help to try simulate it, it would really enhance my understanding? Thank you and have a nice day, sir :)
 

MrChips

Joined Oct 2, 2009
27,727
You cannot do this by simply feeding signals back to the CLK INHIBIT pin.
You need to use flip-flops to create a state-machine.

One pushbutton enables a flip-flip which "arms" the circuit.
Now you can use the OR condition of any two or more outputs to stop counting.
 
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