Microcontroller › 8051 › How to generate 5v supply for AT89C51 controller? › You can use a 7805 regulator
May 1, 2012 at 4:11 pm #7569
You can use a 7805 regulator ic to generate 5v from your 9v battery. Connect pin 1 of 7805 to 9v, pin 2 to ground, and you have 5v across pin 3 and pin 2. pin3 positive 5v and pin2 ground.
It would be nice if you share what project are you doing with 89c51.