Your heuristic is accurate, but I think understanding why it is accurate is as easy as remembering the heuristic.
The near-universal switched-mode power supply works efficiently for a broad range of input voltages and frequencies. If your device runs on DC, with very rare exceptions (some high-end audiophile gear, specialized equipment), it has one of these AC/DC converters (power brick, wall wart) and can run on the mains power anywhere in the world.
All electronics run on DC. Anything with a large motor (not the motor for your optical drive tray) uses AC. Things like light bulbs and resistive heaters in principle work with both AC and DC, but are designed for specific inputs. Getting it wrong can be dangerous, but in almost all cases will result in non-operation or a blown fuse. (If you’re fooling around, or using devices that have a non-standard plug, all bets are off.)
I would not have predicted that. I don’t think I’ve ever seen a power brick not rated for multiple voltages. If I ever find one, the first thing I would do the next time I’m in a 240V country is plug it in and see what happens, but please don’t do that yourself unless you know what you’re doing.
One of my TVs is rated to work anywhere, and another is not. All my computer monitors are rated for multiple voltages. For my TV that’s rated 120V only, I think it’s intentionally not certified for 240V because it’s an NTSC model. There might be a fuse set to blow if you plug it in to 240V, but if not, I would be only mildly surprised if it just worked.
Your heuristic is accurate, but I think understanding why it is accurate is as easy as remembering the heuristic.
The near-universal switched-mode power supply works efficiently for a broad range of input voltages and frequencies. If your device runs on DC, with very rare exceptions (some high-end audiophile gear, specialized equipment), it has one of these AC/DC converters (power brick, wall wart) and can run on the mains power anywhere in the world.
All electronics run on DC. Anything with a large motor (not the motor for your optical drive tray) uses AC. Things like light bulbs and resistive heaters in principle work with both AC and DC, but are designed for specific inputs. Getting it wrong can be dangerous, but in almost all cases will result in non-operation or a blown fuse. (If you’re fooling around, or using devices that have a non-standard plug, all bets are off.)
A counterexample: our baby monitors run on DC and use external switched-mode power supplies, but only take 120V.
I would not have predicted that. I don’t think I’ve ever seen a power brick not rated for multiple voltages. If I ever find one, the first thing I would do the next time I’m in a 240V country is plug it in and see what happens, but please don’t do that yourself unless you know what you’re doing.
It’s the first power brick in this post, above.
We did plug it in, by accident, and ruined it.
Hm, from your explanation I’d expect TVs to work anywhere, but Jeff’s heuristic mentions them as not?
One of my TVs is rated to work anywhere, and another is not. All my computer monitors are rated for multiple voltages. For my TV that’s rated 120V only, I think it’s intentionally not certified for 240V because it’s an NTSC model. There might be a fuse set to blow if you plug it in to 240V, but if not, I would be only mildly surprised if it just worked.