4013 Dual D Flip-Flop

This circuit demonstrates the use of 4013 IC. Either the LED on pin 1 (Q) or the one on pin 2 (not-Q) lights up whenever the DATA input (pin 5) is connected either to a LOW voltage or to a HIGH voltage.The logic states of the outputs can only change when the CLOCK input (pin 3) is high at the clock edge. This follows the truth table of D flip-flop. For this purpose, the 555 timer is set-up to generate a low frequency clock signal (around 1HZ). A LED light is connected to pin 3 so that how the circuit responds to a change from LOW to HIGH can be seen easily. The set/reset inputs of the 4013 IC are connected to 0V.