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I am trying to make a 60 LED chaser. I don't want to use microcontrollers as it makes the job too easy. I have got lots of CD4017s with me. I searched the internet and got a comparatively simple circuit which I am attaching herewith. Instead of 60, I tried out a modified 20 LED version in a breadboard. Now I shall explain my problem. As per the circuit, the LEDs should turn on one at a time. But physically, Q0 of IC3 turns on first. Then Q0 of IC4 turns on (IC3 Q0 is still on). Then IC3 Q0 turns off and IC3 Q1 turns on (IC4 Q0 is still on). That way it's always 2 LEDs n at a time instead of 1. Any idea why? Any inputs deeply appreciated.

enter image description here

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The 4017 is a decoded decade counter which means that one of its outputs is always on. So at reset Q0 is active this will apply to both IC3 and IC4. When you clock IC3 it changes the active output from Q0 to Q1.

If you are trying to achieve a single light that runs from one end of a display to the other you would probably be better off building a shift register to do that using something like several 74HC595s.

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  • \$\begingroup\$ Thanks RoyC. As I have seen, 74HC595 have only 8 outputs. Is there any other shift registers with more than 10 outputs, which also doesn’t need programming? \$\endgroup\$ – Vinodvnmy Mar 28 at 19:46
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Here is a circuit with 9 LEDs on the first CD4017 and 8 LEDs on later CD4017. Then keep adding CD4017 ICs and an AND gate for each one like this:enter image description here

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  • \$\begingroup\$ Thanks Audioguru. Would you recommend any particular AND gate IC? \$\endgroup\$ – Vinodvnmy Mar 29 at 5:46
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Here I put the 1st Johnson counter to clock the 2nd one used as a MUX, but clock all the rest of the counters with a Schmitt trigger Astable variable speed clock. (RC~0.05s for 10Hz)

I put in diodes to but ran out of time to include more counters to the right and diodes to the Left to scan back and forth like this.

The 4017 Counters in this simulation used RESET as negative logic , but should be positive logic. (L to enable counting)

One should use the brightest LEDs possible (20Cd @ 20mA) as these counters only drive a few mA.

Good luck. enter image description here

Total design and connection time 1hr

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