Hi, I need to turn off a certain electronic device X hours (3-4) after i start it. I want this to happen automatically, so I need something that goes between the device and the power outlet, which will automatically switch off the juice after X hours, as if the device was unplugged. I want it to be as easy to use as possible, so that there's just some dial or some buttons where I can set the time after which the device is to be turned off. It's running off of north american standard 120 V, 60 Hz, and if the device is turned off reliably there could be a sfatey hazard.
What kind of thing would do the job/what's it called?
Thanks.