Triggering 12V electro lock

You could add a 5V to 12V boost converter, $1.

How much current can the raspberry supply? And what's the resistance of the

(If I'm understanding the question.) George H.

Poor question phraseology IMO. He will also need some snubbing for the coil's back EMF, or else risk burning his Pi. ;-)

You're a smart fellow, Win. How on *earth* do they do it for that price??? Please tell me, I'd *really* like to know!

You'd need enough current to operate the relay, which might mean driving a transistor switch from an I/O line.

A solid-state relay would be better, but you'll probably still have to search a bit to find a happy match between GPIO drive ability and the relay's current requirement.

My girlfriend teaches English as a second language to Chinese foreign exchange students, who already have a decent faculty with the language and are looking to go into business, etc.

When she describes the American health care system many of them say "Unbelievable! Fantastic! It's the greatest system we've ever heard of! Everyone paying their own way, just like my billionaire Dad does for me.'

yes, assuming the lock already has a 12V supply.

I think he's got a pre-built board with relay and transistor etc.

There are already plenty of low cost door access electric lock power supply controllers that are much more economical than using Arduino.