7809 IC is a simple voltage regulator IC which regulates the voltage to 9v, which means it gives a fixed 9V regulated voltage. It is a monolithic 3 terminal regulator IC. Its 9v output voltage makes is most convenient to use in TTL devices or circuits.
It is a member of 78xx series fixed linear voltage IC. it finds application where the 9v fixed power supply is redistricted to give. The IC gives little fluctuation, in that case, the maker should use a capacitor to remove fluctuations. Buy 7809 regulator IC from Roboelements across India and get only high quality or the original product