This could be used to connect the transformer. (dont think Core have one like this)
EDIT: Well I was wrong, see info from post from Oliver below. (Link deleted)
This toggle switch would more than handle the solenoid current.
Regards
Jim
EDIT: Connection Diagram. I think this is what you are asking, apologies if I am wrong.
The 2.1 socket has a + and - on the top, the + is 12V the - is Ground. For the solenoid to operate the red wire needs 12V and the black wire needs Ground.
