This circuit is used to blink LEDs one by one. It turns On and OFF LED with variable speed. This blinking efffect is also known as Dancing effect of LEDs. Hence the circuit is known as Dancing LED.
Here we are using two iCs IC1 CD4017 and IC2 555. IC555 is in astable mode. An astable multivibrator to provide the clock pulses for the CD4017. For each clock pulse receiving at the clock input (pin14) of IC CD4017, the outputs Q0 to Q9 (refer pin diagram of CD 4017) becomes high one by one alternatively. We are using 8 LEDs LED1-LED8.The LEDs connected to these pins glow in the same fashion to give a dancing effect. The speed of the dancing LEDs depend on the frequency of the clock pulses generated by the IC2.
Here we can change the speed and this can be achieved by varying frequency. For that we are using Variable Resistor R2. With the help of R2 we can change speed of Dancing LED.
Circuit Diagram :
- Resistor : R1 = 10 Kilo Ohm
- Color code for 1 Kilo Ohm: Brown-Black-Orange-Golden
- R3,R4,R5,R6,R7,R8,R9,R10 = 220 Ohm
- Color code for 220 Ohm: Red-Red-Brown-Golden
- Potentiometer:R2= 100 Kilo Ohm
- Electrolyte Capacitor: C1=10uF
- Light Emitting Diode: LED1,LED2,LED3,LED4,LED5,LED6,LED7,LED8
- IC1= IC 555
- IC2=CD 4017
- Battery: 9 Volts
Circuit Building Steps:
Mount two ICs on Bread Board. IC1 CD 4017 and IC2 555. IC 555 is 8 pin IC and CD 4017 is 16 pin IC.
Assign VCC and Ground slots. VCC is indicated by Red wire and Ground by Black wire.
IC 555 is in Astable mode to provide Clock pulses to CD 4017. Short two pins pin 2 and pin 6 of IC 555 to form astable mode.
Connect pin 1 of IC 555 to Ground and pin 4 and 8 of IC 555 to VCC.
Connect potentiometer R2 of 100 Kilo Ohm in circuit. Connect its Red wire to pin 8 and Brown and Black wires to pin 2 of IC 555.
Connect Capacitor C1 of 10uF to pin 6 of IC 555. Connect its positive terminal to pin 6 of 555 and negative terminal to the Ground.
Connect one terminal of resistor R1 of 10Kilo Ohm to pin 7 and another terminal to VCC through Red wire.
connect pin 3 of IC 555 to pin 14 of CD 4017 through yellow wire as shown below.
Connect pin 8, pin 13 and pin 15 of CD 4017 to Ground and pin 16 of CD 4017 to VCC .
Mount Resistance R2 to R9 and LED1 to LED8 on Bread Board.
Connect Anode of LED1 to LED 8 to Resistors R2-R9 respectively.
Short Ground slots present on Bread Board with the help of Black wire.
Connect pin 2 of CD 4017 to Cathode of LED1.
Connect pin 4 of CD 4017 to Cathode of LED2.
Connect pin 7 of CD 4017 to Cathode of LED3.
Connect pin 9 of CD 4017 to Cathode of LED4.
Connect pin 1 of CD 4017 to Cathode of LED5.Connect pin 5 of CD 4017 to Cathode of LED6.
Connect pin 6 of CD 4017 to Cathode of LED7.
Connect pin 10 of CD 4017 to Cathode of LED8.
The time of blinking of LEDs can be varied using R2 which is a variable Resistor. When value of R2 is minimum Blinking speed is maximum. For that vary the knob of potentiometer.