Dancing LED circuit

DANCING LED CIRCUIT

            It is  a simple circuit constructed by a couple of resistors, capacitors and a par of NPN transistors. The components and materials required are listed as follows

• 2N3904 Transitor
  
           
• Resistors
• Capacitors
• Bread Bord
  
• A power source or Battery
  
   The circuit diagram is shown below
  
  

Working

               The circuit is basically a square wave generator which having two states either high or low. The frequency or time period of the square wave are decided by the value of resistor R and capacitor C. When the circuit is powered on either one of the transistor will become ON. At that time the other transistor is off position. For an example assume that the first transistor is on and he second is OFF. At that time the first capacitor C1 starts to charge and when it charges to approximately 0.7V The second transistor will be ON and starts to conduct Hence LED 2 will become glow. At that time Transistor Q1 become OFF and the second capacitor C2 charges by R. This process continues and the output is a square wave. 

              The time period can be calculated by the equation

      T=0.69RC

For example designing a time period of 1 second the values be

Assuming the value of capacitance be 100uF

1 = 0.69(100 × 10^-6)𝑅 

     R=15K