Here is a very simple and useful project of a 12V power supply circuit using LM7812 IC. LM7812 is a three terminal fixed voltage regulator IC comes in TO220 package. It has many built in features like thermal shutdown, short circuit protection, safe operating area protection etc. The output current of
the IC is 1A which is enough to run most electronic devices.
It is an IC of LM78xx series, this series contains many fixed voltage ICs made for different voltage requirements. For example LM7809 IC is made for 9 volt fix output, while LM7805 produces 5 volts). These type of ICs are commonly used in regulated power supply circuits.