RFID/NFC computer lock?
I am curious if any of you have an idea for something that could detect a bracelet from 5-10 feet and when it leaves, issue a sleep command to a computer. I think it would be relatively easy to issue the command from an arduino, but I'm not very sure on which tags and readers to use for the right range. The idea would be for the computer to automatically sleep/lock when you leave the room.
So what frequencies/types of tags and readers should I look into that will offer a decent range, that is close enough not to loose connection reaching across the desk or walking a few feet across the room, but won't work from a few rooms down the hall, and will interface well with an arduino.