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# Stopping at a led in a cascading 18 running circuit

#### Newbie_Garbo

Nov 10, 2023
3
I have 3 4017 IC, cascading with a 4081 IC for the cascading function, and a 555 timer, where each 3mm LED is connected to the breadboard both negative and output positive wire

I asked around, so I bought only a 74hc74 IC for a "d flip flop" but I don't know and can't understand how can I apply, according to yt tutorials, to my circuit so I can stop an led.

Thank you for anyone who will answer

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,828
#1: Show us a circuit diagram. Your verbal description doesn't tell us much.
#2: From what little you offer I take it that the 555 is used as an astable multivibrator to generate the clock for ypur 4017 counter chain. To stop the counter from counting you stop the clock by halting the 555 or use the "clock inhibit" pin of teh 4017.

#### Newbie_Garbo

Nov 10, 2023
3
#1: Show us a circuit diagram. Your verbal description doesn't tell us much.
#2: From what little you offer I take it that the 555 is used as an astable multivibrator to generate the clock for ypur 4017 counter chain. To stop the counter from counting you stop the clock by halting the 555 or use the "clock inhibit" pin of teh 4017.
Its very similar to this picture taken from the internet, my clock output is a ne555 Timer with 10k Ohm resistors and 4.7 microFarads 25V Rated, set in as you have said an astable multivibrator, I have 2 push buttons so can I just connect and send a positive(?) - (Sorry Im a complete beginner) - to the 3 4017 IC clock inhibit pins?

Edit: Also I use a 9 Volt Battery for my power supply

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#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,828
can I just connect and send a positive(?)
You can use the pushbuttons to connect the clock inhibit pin to Vcc (positive supply voltage).
This alone is insufficient: you will also need a pull-down resistor to ensure a defined logic low level at the pin when the pushbutton is not pressed. Any resistor between 1 k and 100 k should be fine.

#### Newbie_Garbo

Nov 10, 2023
3
You can use the pushbuttons to connect the clock inhibit pin to Vcc (positive supply voltage).
This alone is insufficient: you will also need a pull-down resistor to ensure a defined logic low level at the pin when the pushbutton is not pressed. Any resistor between 1 k and 100 k should be fine.
Thank you for the reply you are being a great help, so I will need 3 pull down rated to 1k to 100k And set them between each ic or can I use only one and have 3 jumpers to send the signal to the clk inhibit pins of each 4017 IC?

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,828
Depends on what you want to achieve. With one pushbutton for each 4017, you will stzop only that chip and those following in the chain from counting.
With a single pushbutton for all three 4017s you will stop all counters at the same time.

#### kellys_eye

Jun 25, 2010
6,514
You could wire output #16 of the 4017 string to the clock inhibit pin (via an inverter - simple transistor and resistor job) to stop it at 15.

#### AnalogKid

Jun 10, 2015
2,929
Your question is not clear. What is it you are trying to do? What is the circuit supposed to do? Can you provide a more complete schematic with the switches, any resistors and other components, and the LEDs?

Where are you located?

ak

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