USB LED's ?

[ssc456]

is it possible to strip down a usb cable and to find out which of the cables are power cables and run some 5V leds off it ?

 

[muz]

Yer that is possible , although i dunno if 5v leds are readily available but if not just get like a 3.3v and throw a protection resistor in there
and the usb pinout is

1 VCC Red +5 VDC
2 D- White Data -
3 D+ Green Data +
4 GND Black Ground
sso you would connect the led to the 1st and 4th pin

 

[Remeniz]

Use this to calculate the value of the voltage drop resistor.

 

[muz]

Use this to calculate the value of the voltage drop resistor.

wish i had known about this last time i did an led job i worked it all out using the ohms law calculation

as for using about a 3v led you will want aprox 150ohms and max current of an led is about 15 miliamps

 

[Remeniz]

I know what you mean. Studied all this in college. Then I got lazy and used Excel to make my calculations.

 

[muz]

I know what you mean. Studied all this in college. Then I got lazy and used Excel to make my calculations.

yer i do electronics in college now , got to learn all sorts of formula

 

[BrynF_UK]

You can easily get 5v LED's

 

[muz]

can you ,havent had experience with them myself we only use 3.3v blue ones max at college

 

[BrynF_UK]

Yeah I use them sometimes when I cant be bothered to find resistors and stuff, just to test things

5v and 12v LED's

 

[ssc456]

You can easily get 5v LED's

yeah theres lots of 5v LEDs about specially at maplins + i dont have a lort of experience with LED's ive only done 1 project before which was a light in the hood of my fish tank

i tried,

2 X 1.5V batterie -------- Switch --------- 3V LED ---------- 3V LED ------- 3V LED ------------ 2X 1.5V batteries,

that didnt work at all.

so in the end i did what i thought was wrong but it worked,

2X1.5V batteries ----------Switch --------------3V LED
................................../......|......\.............................
.............................../.........|.........\
........................3V LED.....3V LED......3V LED

basicly i had 6 LEDs and ran 6 cables from the switch to each led and 6 cabled from the negative back to the battery negative, this was very messy but it worked,

why didnt it work going 3V LED - 3V LED - 3V LED ?????

edit. jus looked at that link, so lets say i got 3V battery and 3V LED after the 1st LED id need a resistor = to the amount of current the 1st LED takes then after the 2nd id need 1 that the 1st and 2nd LED current takes?

i dont understand resistors help me please, noob