Bi-Color Dancing Light

LED (Light Emitting Diode) is a semiconductor. We know that the diode allows the current in one direction and does not allow the reverse current which will affect the components in circuit. LED also does the same function but will emit light when it allows the current. There are lots of application of LED in electronic devices.

The circuit diagram is given below
  • The circuit consists of IC-555 timer, resisters, capacitor, POT and LED's.
  • Here timer is used for setting the sequential flow rate for the LED's

Circuit diagram of Bi-color dancing light
 1st and 8th pins of 555 timer are used to provide power, Vcc, and GND respectively.4th is the Reset pin which is an active low input and is tide to Vcc to avoid accidental resets.5th is the control voltage pin which is not used in this application.

LED ON-OFF period is determined by varying POT resistors and the capacitor.

We can determine the time period theoretically by the equation
T=1.1RC

And this R depends upon the POT resistance (i.e. Variable Resistance)

When the output is LOW(0v) upper LED glows and when the output is HIGH(5V) lower LED glows. You can use higher supply voltages if you need to drive more LED. You can use higher supply voltages if you need to drive more LEDs. LM/NE555 can work upto 16V (i.e. Vcc) and SE555 can work upto 18V (i.e. Vcc). 555 can source or sink upto 200mA current, if you need more current use a transistor driver. You can also connect this circuit to relay for controlling incandescent lamps as shown below.
Transistor driver circuit with relay
Here transistor acts as switch, when the base input is HIGH transistor turns on and the relay energized. Since the output of the 555 is square wave, the relay energizes and de-energizes continuously. Incandescent lamp turns ON alternatively since there are connected to normal open (NO) and normally close(NC) of the relay output. 

Video