# COMMUNITY : FORUMS : TECH

## Reusing desktop and laptop monitor CCFLs and power supplies to make a floodlight

I'm using a collection of broken laptop and desktop monitors I got free from a repair workshop to assemble a floodlight/spotlight from the CCFLs and their inverters. The desktop monitor power supplies take mains voltage (240 V) and power the CCFLs but also seem to provide a 5 V and 12 V supply to the electronics that control the LCD. The laptop inverters themselves accept either 5 V in some cases or 12 V in others so naturally I want to run the laptop inverters off the 12 V and 5 V supply because otherwise it's wasted. The problem is that I don't know how much power I can draw from the 5 V and 12 V of the power supply.

I've had a look at the back of a monitor that says it draws 0.7 A at 240 V. What translates to 168 W which is more than I was expecting. Assuming that the four built-in CCFLs use 8 W each, that would still leave 136 W. Assuming the power supply is only 60% efficient that leaves (168 W x 60%) - (4 x 8 W) = ~68 W. I've no way to tell how that's distributed across the 12 V and 5 V but if it's 34 W each then I can draw 2.8 A from 12 V and 6.8 A from 5 V?

I figure I can probably, maybe attach eight laptop inverters to each desktop PSU (four on 12 V (1.6 A) and four on 5 V (4 A)?