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[bigsammoe]

were in the xbox can u find 3volt source i have some leds but they are for 3 volt source with a 470ohms restior

[Modchip-Man]

the 470 ohm resitor should go inline with a 5v source. If i can remember right, the 470 will bring it for 5v to 3v. If you need to get closer, there is a stanby wire, but that's on all the time....

Hope this helps,

Peace,

M-M

[AErph]

You don't need a 3 volt source, your LEDs require 3 volts to operate, the rest of the voltage must be dissipated by a resistor.

What becomes important is resistor size, since you need to limit current to the LED, otherwise it'll change colors because of carbon build up, and maybe even smoke.

what are the LEDs your using? what is the desired forward current and voltage to operate them properly?

[brojimh]

here is a link to a resistor calculator that you can download, it runs in a dos window.

Just plug in your source voltage, then your forward voltage drop, then forward current and it will tell you what resistor you need to use.

Those figures can be found from the website that you are ordering your leds from.

I use 3mm leds to add underglow.  I had to figure out what resistor I needed to I went to the website where I ordered them and used this formula:

Number of leds in circuit:  10
Source Voltage (power supply from xbox):  5
Voltage (forward) drop of one led:  3.3
Ma (forward current) One led will draw:  20

and it told me to use a resistor that was 9.1 ohms @ 1/2 watt.

[frank10]

There is a 3.3v source on the LPC port (pin 9)

This post has been edited by frank10: Feb 15 2005, 07:45 PM

[sting369]

well if the power supply is the same as a computer which im almost positive it is, the purple wire should supply 3.3v. You may want to check with a multimeter before trying. I dont want to be blamed for killing anyones xbox.

[frank10]

You could also go with a 3pin LM3940 (national semiconductors) regulator to convert from 5v to 3.3v.  These are pretty cheap and don't waste as much energy as resistors.