15v supply

i need to make a 15v supply which can make a 12v bulb to light up for 10 mins.
i experimented using 2 lm7815 and made a simple linear circuit. i tried to connect the bulb and it did not light and truned off my supply. i tested the schematic on multisim and it worked there, so i don't know what caused for my light not to turn on... please help me.. i have to do a variable supply as wel...

Show your circuit schematic. Why would you use 2 LM7815s for a single supply?

When you try to turn on a 12v globe, the resistance of the filament is very low and the globe takes 6 times the operating current. That's why you cannot power it from a 3-terminal regulator.
You need a simple transistor regulator.