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I have a quantity of LCD panels (from a wide range of dead laptop) and I would like to use only the CCFL + diffusors as a "creative" light source for a room in my house.

Is there some sort of "universal" CCFL supply that I can use to replace the panels inverter (that needs various undocumented control signals to works)?

Would those inverters for single CCFL tubes like this works with the panels (that have more than one lamp but just a single connection)?

http://www.lamptron.com/products/view/4_Port_CCFL_Inverter_with_Alum_housing

radagast
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Axeman
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1 Answers1

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Effectively all you're salvaging is a small fluorescent light bulb. You could try buying an inverter that seems like a reasonable match for the typical bulb size from Digikey and seeing if it will drive each of the tubes, and if so, buy enough for your project of lighting them all up.
http://parts.digikey.com/1/parts-kws/ccfl-inverter

Aside from what tube size the inverter will drive, some notable variables will be the DC input voltage range and the connector to the bulb (which is not standardized). You might care whether the brightness control is an analog knob on the board or a digital control signal. There's a lot of variation in board shape and component height (for fitting into different types of products) that may not matter to you.

If the project gets too complicated, you could try salvaging only the diffuser panels and replacing the bulbs with a single bulb part number that you control. That way you can match the tube and the inverter and have control over the whole design. As the inverter cost is vastly more than the bulb cost, you're not saving much money by reusing old bulbs (which are likely already much less bright than when they were new).

For more technical details, you could start with this app note from Linear Tech.
http://cds.linear.com/docs/Application%20Note/an65f.pdf

Matt B.
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  • You're right about costs... I could consider salvaging also original inverters, but documentation about those boards are almost inexistent or extremely difficult to find. Vcc and Gnd could be located easily, but other control signals needed must be guessed, without an already working hardware... – Axeman Dec 05 '11 at 08:22
  • Since you probably want maximum brightness, the control signals might not have to be understood all that well. Have you tried removing the inverter board & bulb, feeding it power, and seeing if it lights up? How many pins are on the input side of the inverter board? It might only have DC power +/-, on/off, and brightness control (PWM etc). If you can take a look with a scope things might be easier to understand - but stay on the low-voltage side of the board! You only really need to know what the input connector pins are doing. Is there brand & part # labeling on the IC or the board? – Matt B. Dec 05 '11 at 11:52
  • If you buy any new CCFL parts, you'll end up with a very expensive, very dim lighting system. A <$10 LED flashlight will put out more light than a laptop backlight. Maybe you can just put some white LEDs on the diffuser? – Matt B. Dec 05 '11 at 12:03
  • Brightness is not an issue. I don't need to fill a room with light. I would like to use them to illuminate a sort of 3d-like layered scene. A normal 14" LCD monitor with a white screen is enough. But I need them to be very thin and very uniform. To answer your question, inverters that I have checket have all 5 or 6 pins on the input connector, no marking/brand/logo on the IC or on the board. Simply powering them (via a bench supply, slowly raising voltage to 12V) does not works. I could easily check signals with my Tek scope, but I don't have a working machine to read original signals. – Axeman Dec 05 '11 at 21:32
  • If you are sure which input pins are power & ground, and what voltage the signal pins run at, you could try powering the board and then toggling through all the combinations of high/low on the signal pins. You wouldn't have control over brightness but you might find a signal pattern that turns it on at full brightness. Also the laptop doesn't have to boot up, it just needs to turn on enough to light up the backlight, then you can scope the pins for some information, if the machine can get that far. – Matt B. Dec 07 '11 at 03:14