What DC voltage does an average LCD monitor use?

March 27, 2009 5:41 PM

What DC voltage does an average LCD monitor use?

I'm trying to power an LCD monitor from a 12-volt battery, but I don't want to waste efficiency by inverting it to a 120-volt AC, then letting the monitor turn it back into DC current again.

posted by leafxor to technology (4 comments total)

Does the LCD in question have an external power brick? If so, the output voltage is usually specified on it. If the power supply is internal, you're going to have a hard time connecting up a DC power source without taking the back of the LCD apart.
posted by knave at 6:33 PM on March 27

Watching over a friend's shoulder while he took apart his monitor to try and fix it revealed several transformers. I'm willing to bet at least one of them steps up directly from 120V to whatever it takes to power the backlight - probably over 1kV. You might have luck powering some of the other components inside the monitor but that would be a challenging project with little real gain.
posted by Dmenet at 6:42 PM on March 27

If you've already got the monitor, then it doesn't matter what voltage an average one uses--you care about the one you already have. Like knave said, if the power supply is external it's easy to just read it off there.

If it's internal, well, the couple of LCD monitors I've opened up have had power supply boards with several different voltage outputs all in use simultaneously. So you would have to have some kind power supply in there anyway, rather than just bypassing the whole thing and hooking 12 volts directly to the board somewhere.

And if you don't have the monitor already, then you want to look for one with an external 12 volt DC power brick. Probably an older model since most of them seem to be coming with internal power supplies these days.
posted by FishBike at 6:45 PM on March 27

An acquaintance was trying to do the same thing recently. IIRC, his monitor generated 12VDC internally, then regulated that to 5/3.3/1.8 V for logic and the LCD proper and so on, and had an inverter going from 12V to 200V or whatever the backlight ran at. (Dunno why they went from 120VAC to 12VDC then back up to 200; maybe some safety / certification / internationalization thing.)
posted by hattifattener at 8:41 PM on March 27