This is a simple sequential LED flasher (sequentially left to right), which is based on the popular Johnson's Decade Counter IC 4017. The speed of shifting is directly depended on the frequency of a clock signal. The clock signal is generated from an astable multivibrator circuit, which is based on the popular IC 555. A potentiometer is used for frequency adjustment. We think that the specific circuit can be an ideal starting point for beginners in electronics.
The normal functioning of the IC4017 involves sequential shifting of its outputs 1 to 11, in response to a clock signal applied at its pin #14. The outputs become high in sequence such that one output becomes “high” immediately after the previous one becomes “low”. Each output goes high in turn, as counting advances.
There are 10 LEDs connected to the outputs and the above sequence gives a running or chasing effect. A flashing “dot” runs from start to finish and the sequence is repeated infinitely. The speed of shifting or the sequencing of the outputs is directly depended on the frequency of the input clock signal. There are unlimited options to get an oscillator configuration using ICs like 4060, 4093, 555, 741, transistor mutivibrators etc. Here, we use an astable multivibrator which is based on the popular IC 555, and produces a square wave. The frequency of the oscillator can be adjusted from R2 potentiometer.
The simple sequential LED flasher can be powered from a 9V power supply unit, or a battery may be used. With minor modifications, the circuit can also be powered from 5V or 12V power sources. Modifications include altering the values of R3-R12. Normal values for R3-R12 are 220Ω, 330Ω and 390Ω for 5V, 9V and 12V power supply, respectively. The required supply current is less than 40mA.
The construction procedure is quite simple, given the single sided PCB which we provide below. The circuit can be assembled by simply soldering all the components at the provided circuit board. Except for the components, one wire bridge is also required to be soldered at the specific pads, indicated on the composite drawing.
The entire circuit of this LED running light may be fitted in a nice looking enclosure with the LEDs projecting out of the box.
After building the prototype, we had a nice idea, to embed the circuit in an old wall clock. Please, watch our demonstration video on youtube and see the old wall clock, which has now a new fancy look.
Besides its simplicity, the sequential led flasher can be used in many ideas. A friend told us, that it uses the circuit in his car for emergency break lights, and another one, told us that it uses the circuit for emergency rear lights on his bicycle. We hope that you’ll love this circuit and you’ll have a lot of fun.
Author: A.G
Download section
Sequential LED Flasher electronic schematic
Sequential LED Flasher PCB Artwork and composite drawing
