Hi as you can guess by the question I am a novice at electronics, I need to know how can I build a unit to enable me to convert 12v ac to 9v dc I have a 240v doorbell transformer that gives me the 12v I take it that being it is 240v ac in it would be 12v ac out, how would I go about checking out if it was either ac or dc out put. It it turned out to be 12dc I would still need to get it down to 9v to power a door entry system. Can any one help please. :)