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.

 

For a resistor to drop the voltage, you need current flowing, i.e. V=I*R. What is your circuit? Also, a simple series resistor circuit will only work for a constant current type of load (like your LED). If you have a device that needs varying amount of current then the series resistor will provide varying levels of voltage drop.

 

im not sure exactly and that is the problem I scavenged the parts for it off the pc board of the dvd player it came with, an apex digital pd-480. it needs a 9v a 3.3. and a ground. the 9v is going to need varying current im sure cause it has a transformer putting out a lot of voltage 700+. So I was thinking of using some diodes to get the right voltage im not sure what the current needs are I cant find any schematics for it so im tracing out the circuit and im going to make a schematic and try to make sense of it from there. Thanks for the assist.

 

oops meant to show some pics

 

http://www.newegg.com/Product/Produc...82E16823175001

problem solved..

i've had this keyboard for awhile now..its great

 

I would say that would be but I have a nice wireless setup already. Btw in your sig it says "crouch rocket" is that supposed to be "crotch rocket". I may have to break down and get something like that.