What is the use of IC 7809?

Answer 1

The 7809 IC is a three-terminal nine volt linear regulator IC. You provide 11 or more volts on two terminals, and the IC provides a regulated 9 volts on two terminals, one of which is common, i.e. ground. It is useful in simple circuits, where only a few amperes is required, though it can be boosted using power transistors. For higher current applications, however, a switching regulator design is better.

Answer 2

IC 7809 is a voltage regulator which provides regulated 9V supply to the electronic circuit. It is widely used in regulated power supplies, in relay operated motor starters etc.

This IC has 3 pins, i.e. INPUT, COMMON & OUTPUT.

Maximum voltage given to the input is 23V DC but as per my experience, it is safe if we provide maximum 15V.

Common pin of IC is grounded and output, i.e. 9V is fed to the circuit to perform specific function.