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js9924 · 04-24-2008, 05:27 PM

The project:
I am trying to hook up a ccfl backlight from a portable dvd player to my computer for a keyboard light, to type in the dark. It uses a 3.3v for digital and a 9v into a transformer for the light power and a ground.

Heres my problem:
I did the calculations and figured out what value resistors i need to get the correct voltage, but they have no effect on the voltage. I am tapping into the 12v from the psu in my comp for each and kicking them down with the resistors (ex. a 330 ohm should give me around 3.6v with a 12v source) i did this for my truck with an led and it works fine. So why does the resistor have no effect? I tested the resistor and it is good. Im an electronics tech so this is really frustrating me. Please help if you can.

04-24-2008, 05:27 PM	#1 (permalink)
js9924 Registered User Join Date: Feb 2007 Location: Tampa, Fl Posts: 183	trouble with circuit for light The project: I am trying to hook up a ccfl backlight from a portable dvd player to my computer for a keyboard light, to type in the dark. It uses a 3.3v for digital and a 9v into a transformer for the light power and a ground. Heres my problem: I did the calculations and figured out what value resistors i need to get the correct voltage, but they have no effect on the voltage. I am tapping into the 12v from the psu in my comp for each and kicking them down with the resistors (ex. a 330 ohm should give me around 3.6v with a 12v source) i did this for my truck with an led and it works fine. So why does the resistor have no effect? I tested the resistor and it is good. Im an electronics tech so this is really frustrating me. Please help if you can. __________________ '94 T100 3.0 My mods page: http://www.angelfire.com/fl4/dmb Last edited by js9924; 04-24-2008 at 05:36 PM.