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How to Make a LED Chaser cum Blinker Circuit Using IC 4017

  The presented circuit
was requested by Mr.Joe, one of the keen followers of this blog. The circuit
initially was intended to be used for generating LED strobe light effects and
was asked to be modified such that it could be used as an LED sequencer as well
as a blinker. The change over would be implemented via a toggle switch.

The circuit diagram may be understood with the following points:
The IC 4017 is not new to us and we all know how versatile
and competent this device is. Basically the IC a Johnson’s decade counter/divide
by 10 IC, fundamentally used in applications where sequencing positive output
signals are required or desired.
 The sequencing or the
orderly shifting of the outputs take place in response to a clock pulse that
needs to be applied at the clock input pin #14 of the IC.
With every rising positive edge of the clock input, the IC
responds and pushes its output’s positive from the existing pin out to the next
pin out in the order.
Here a couple of NOT gates are used as a oscillator for
providing the above clock pulses to the IC 4017. VR1 may be adjuted for
determining or fixing the speed of the sequencing.
The outputs of the IC are connected to an array of LEDs in a
specific order which makes the LEDs look like as if they are running or chasing
during the operations.
If the circuit would be required only to produce the chasing
effect, the diodes would not be required, however as per the present ask the
diodes become important and allows the circuit to be used as a blinker also,
depending upon the position of the switch S1.
When the switch S1 is positioned at A, the circuit behaves
like a light chaser and produces the normal chasing effect over the LEDs which
start illuminating in sequence from top to the bottom, repeating the operations
as long as the circuit remains powered.
As soon as S1 is flicked toward B, the clock signals from
the oscillator are shifted into the input of the transistor T1, which instantly
stats to pulsate all the LEDs together in response to the received clocks from
N1/N2 configuration.
Thus as per the requirement we have successfully modified an
ordinary light chaser circuit with an additional feature through which the
circuit now is also able to function as a LED flasher.
Do not forget to connect the inputs of the remaining unused
gates from the IC 4049 either to the positive or the negative of the supply.
The supply pins of the IC 4049 also need to be connected to the relevant supply
rails of the circuit, kindly refer to the datasheet of the IC.
Tf all the ten outputs of the IC 4017 are required to be integrated with LED sequencing, just connect pin #15 of the IC to ground and use the left over outputs of the IC for the required sequencing of the LEDs in the order of: 3,2,4,7,10,1,5,6,9,11

Parts List
The fooliwng parts will be needed for making this LED light
chaser cum flaher circuit:
R1, R2, R3 = 1K,
R4 = 100k
VR1 = 100K linear pot.
All LED resistors are = 470 Ohms,
All diodes are = 1N4148,

ch_client = “swagatam”;
ch_width = 550;
ch_height = 90;
ch_type = “mpu”;
ch_sid = “Chitika Default”;
ch_backfill = 1;
ch_color_site_link = “#3D76CC”;
ch_color_title = “#3D76CC”;
ch_color_border = “#FFFFFF”;
ch_color_text = “#000000”;
ch_color_bg = “#FFFFFF”;

All LEDs = RED, 5mm or as per choice,

T1 = 2N2907, or 8550 or 187,
C1 = 10uF/25V
C2 = 0.1uF,
IC1 = 4017,
N1, N2 = IC4049

20 Comments

  1. You said a clock pulse needed to be applied to input 14. Would that just be applying power to the chip or something different.

    • Clock pulse means a frequency or generation of alternate positive and negative pulses.
      The function is done by the gates N1, N2, the output from N2 provides the required clock pulses to pin14 of the IC 4017 when the switch is connected to point A.

      Regards.

  2. Good day sir swagatam. pls i want to understand something about this interesting circuit. Is it thesame set of LED that chase that also blink or we need to connect a different set of LEDs to the transistor for the blinking operation? Pls clear me on this. Thanks as i await your reply

    • Hi Tombari,

      The circuit can be made to work both ways.
      If you connect separate LEDs to the lower diodes, they will blink while the upper LEDs will chase depending upon the position of S1.
      If you connect the lower diodes to the black points of the upper diodes, the connected LEDs can be made to chase or blink depending upon the position of the switchS1

      Regards.

  3. Thank you for your response. Please i will like to propose a modified circuit in which if we have two set of LEDs then the upper ones should be chasing while the lower ones are flashing simultaneously. A second modified circuit should be such that the switching action from chasing to flashing is done automatically after a set time either by a relay or other timing sub unit. Thanks. Electronics is the best field!

    • Hello Swagatam,
      I am in need of assistance. I want to build a small LED array of 5-6 different colored LEDs that light one at a time for a period of 3-5 seconds in a loop. The LED sequencers I see everywhere light too fast. I want them to cycle through the 5-6 LEDs at a slower rate and stay illuminated for 3-5 seconds before moving to the next blub.
      Can you assist me with this?

      Thanks,
      Steve

    • Hello Steve,

      You just need to increase the value of the oscillator capacitor C1 for the desired effects. Increase the value appropriately until you get the desired effects.

  4. Is it possible to make a circuit which will be a blinker and a sequencer? As in, the first LED will be turned ON for 10 milliseconds and then turned OFF for 2 seconds, followed by the next LED doing the same?

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