What is chattering as applied to mechanical switches used in digital systems and why do they occur?  What is its effect on the functioning of a sequential circuit?

Ans

Chattering:

Mechanical switches are utilized in digital systems like input devices by that digital information (0 or 1) is entered in the system. While the arm of the switch is thrown from one position to the other, this bounces or chatters some times before at last coming to the root in the position of contact. This is termed as bouncing or chattering. Such bounce is result of the spring loaded impact of the switch throughout contact and the pole contacts. Inside a sequential circuit, if a 1 is to be entered by a switch after that the switch is thrown to the consequent position, immediately this is thrown to this position, the output is 1 although the output oscillates in between 0 and 1 for some times because of make and break or bouncing of the switch at the point of contact before coming to rest. These change the output of the sequential circuit and create difficulties in the operation of the system. These problems are removed by using bounce - free elimination switches.