Here I discussed very important portion of digital electronics that What is a Flip-Flop? A flip-flop is a bistable circuit. Both of its output states are stable. The circuit remains in a particular output state indefinitely until something is done to change that output status. That means it can store any single bit data until we changed that. The bistable multivibrator circuit, these two states were those of the output transistor in saturation representing a LOW output and in cut-off representing a HIGH output. If the LOW and HIGH outputs are respectively regarded as ‘0’ and ‘1’, then the output can either be a ‘0’ or a ‘1’. See the bistable circuit diagram in bellow.
As we know the output either a ‘0’ or a ‘1’ can be held indefinitely until the circuit is appropriately triggered to go to the other state, the circuit is said to have memory. It is capable of storing one binary digit or one bit of digital information. Also, if we recall the functioning of the bistable multivibrator circuit, we find that, when one of the transistors was in saturation, the other was in cut-off. This implies that, if we had taken outputs from the collectors of both transistors, then the two outputs would be complementary.
Now question is What is a Flip-Flop? and how it relate with bisatable multivibator.
As like Bistable Multivibator a flipflop also has two stable states of output Q and Q^. it can store the output untill we want to changed it. In the flip-flops of various types that are available in IC form, we will see that all these devices offer complementary outputs usually designated as Q and Q^.
Now one of most popular flip-flop is R-S flipflop. The R-S flip-flop is the most basic of all flip-flops. The letters ‘R’ and ‘S’ here stand for RESET and SET. When the flip-flop is SET, its Q output goes to a ‘1’ state, and when it is RESET it goes to a ‘0’ state. The Q output is the complement of the Q output at all times. Now see in bellow the circuit diagram of R-S flipflop.