optointerrupter circuits guide

hello
i have a problem with this circuits .
i use 12 volt dc power (old computer power).
my electro magnet need 12 volt to give best performance.

but when i run this circuits ,input voltage for electromagnet is 6 volt.

please guide me ,what can i get 12 volt in input for electromagnet.

i use optointerrupter in circuits
thanks for helping
(sorry for my bad english)

Sorry your scematic is not very clear because you haven't used the proper symbols.

My guess is that the opto-interrupter doesn't allow enough current through the base of the transistor to saturate it properly.

Please post a proper schematic, using electronic symbols.