Hi all! First of all, sorry for my bad english 
I've an electronic lock. This lock get unlocked using a 12v input, but i've tried using a 9v battery and it works great.
Now i want to unlock this lock using an Arduino output pin. In other words, i want transform the 5v Arduino signal to 9v output so i can unlock the door. I can use an external 9v battery to supply the output, but i don't know how. There is an IC that allow me to gain 9v current to the lock only when a pin of the Arduino is powered ? Is that possibile without using a relay ?
Thanks a lot!
Use an NPN transistor, with a suitable base resistor, to control the current to the lock.
See Tutorial 5 for Arduino: Motors and Transistors – JeremyBlum.com