White LED

[Steve-O]

Hi,
Anyone Got a bright "White" LED Laying around that they could send me so I can get my Worm Light back up and running ?? Also do you need to wire a Resistor up to stop it buring out LEDs or can a LED Take upto 3.6 Volts (I know in electonics we wired up resistors to leds, but that was when we were connecting them to 9Volt batteries...??)

If you have a White LED that you could send me, please send me a Private message

Thanks

 

[zenocha]

if your in the uk get yourself down to maplins, theyll have white leds, as for the resistor it depends on therating of the led.

 

[divadsci]

a 330 ohm resistor is typical

 

[Steve-O]

I was reading a site and it said RED LED is rated up to 1.6 volts... White LED is rated up to 3 - 3.6 Volts.. so it looks like it will be fine to use without a resistor... hhmmm...

 

[Squidge]

1) It's not the voltage that kills LEDs, it's the current.

2) Resistors don't alter the voltage, they alter the available current.

Take notice, as I'll quiz you about this next week

 

[blipped4]

Yeah maplin is ace!I go to ythe one in warrington,I have a bright white led pm if you want it.

 

[zenocha]

i personally hate maplins, although they are the only highstreet shop you can get components from 9/10 times i go to get bits for a project i have to order at least one of them, they are getting worse for components, they sell too many crap toys now :angry:

 

[Axeman]

Must depend on your branch - mine has always been very good.

 

[Steve-O]

1) It's not the voltage that kills LEDs, it's the current.

2) Resistors don't alter the voltage, they alter the available current.

Take notice, as I'll quiz you about this next week

so should I use a 330 ohm resistor like what divadsci said??



Ill get ready for the Quiz

 

[zenocha]

it depends on what the led is drwing, test the voltage with a multimeter if its within the recommend voltage then youll be fine, if not use R=V/I to find the size of resistor to use, (the voltage you use in the formula should be the source voltage minus the voltage you want for the led) Remember if your using mA the result will be kohms. and squidge resistors in a series circuit affect voltage not current, because according to kirchoffs law in a series circuit VT=V1+V2+V3 and the current is constant throught.

 

[Squidge]

I stand corrected !

 

[Steve-O]

I stand corrected !

I knew there was something odd about your Answer hehe...

Output I get from the EXT port is 3.6 Volts on fully charged batteries and the White LEDs are rated 3 - 3.6 volts...

 

[blipped4]

GP32 Spain has an led changing guide you could take a look there,But if you would like i could translate it if you want.

 

[EdZ]

Actually, it IS the current that kills the LEDs. 20ma is the RATED max for MOST LEDs, but they can usually go higher without many problems. general rule of thumb it 50ohms for every volt, so 3.6 volts would be 200ohms roundabouts.

 

[Squidge]

Oh right, so I wasn't that wrong