i would like to power a stip of led's or 1 Cold Cathode using a usb is there away to do that thanks in advance

want to use a pc's usb to power a Cold Cathode light or led lights for a pc trolly that i am building

jdedmond8 years ago
Powering a strip of LEDs would be MUCH easier (cheaper, less components and more efficient) than powering a cc tube.
USB port supplies 5v at 100mA (or up to 500mA on 'request' by hardware/software interface). Check the Wikipedia article on http://en.wikipedia.org/wiki/Usb for the pinouts of the connector. The easiest way is to get hold of an unwanted USB A cable and chop it in half. The +5 is usually red and the 0v (GND) is usually black.
There is a good led series resistor calculator http://led.linear1.org/led.wiz. i like it, as it provides a schematic drawing of how to connect the LEDs.
Source voltage is 5v. Forward current (If) and forward voltage (Vf) are usually in the range of 15mA and 2v respectiveley.
For more info, search USB Light or USB LED here on instructables.

While the "standard" is 100 ma, many manufacturers allow for more current to keep up with current demand.
lemonie8 years ago
If you want a lot of light, tap into a spare molex connector, 12V is yellow, GND is black. L