What size resistor?

[drell42]

Okay I have a 2.5v LED that I need to hook up, but i need to know what size resistor to use, ive google ive asked im confused.... PLEASE HELP!

Thanks, Rick!

[Leenis24]

use this to find out
http://ourworld.compuserve.com/homepages/Bill_Bowden/led.htm

v = volts mA = milliampere(Milliampere, an SI unit of electric current, worth 0.001 Amp) Ohm = electrical resistance or electrical impedance

with 1 led, at 2.5v, a 15 mA current, and a 14.2v source(the alternator will push 14.2 volts), it says a 750 Ohm. I would use a resistor higher than that number. I personaly would just use a 1k (1000 Ohm) resistor that way your safe.

[johnnyfive]

check this out http://led.linear1.org/led.wiz

very handy little helper when it comes to wiring LED's

it will give values for resistors, and pratical array patterns if you are wiring multiple LED's it will even help you with resitor color codes, and give you a wire diagram for the layout :)

[Leenis24]

hey johnnyfive, that site is really cool, i bookmarked it.

[SophieSleeps]

Okay I have a 2.5v LED that I need to hook up, but i need to know what size resistor to use, ive google ive asked im confused.... PLEASE HELP!

Thanks, Rick!

You'll need to know the operating current of the LED before you can determine the resistor needed.

A 1/4 watt resistor is plenty. If you go up in wattage it won't do anything...so if you can only find 1/2 watt it won't make a difference.

If you are putting multiple LED's in...I suggest wiring them up in series (connect the + of one LED to the - on another and create a chain) because it seems easier than running them in parallel.

What is your project? Pics? LED's rock

http://users.rcn.com/sscustom/heads2/12.jpg

[drell42]

use this to find out
http://ourworld.compuserve.com/homepages/Bill_Bowden/led.htm

v = volts mA = milliampere(Milliampere, an SI unit of electric current, worth 0.001 Amp) Ohm = electrical resistance or electrical impedance

with 1 led, at 2.5v, a 15 mA current, and a 14.2v source(the alternator will push 14.2 volts), it says a 750 Ohm. I would use a resistor higher than that number. I personaly would just use a 1k (1000 Ohm) resistor that way your safe.

Thats what i thought so I tried it again i guess that the first one that I had was defective. the LED is so that I know that the neon is on because I dont want to use the fugly switch that came with them!

[pennystocks]

So you use hot glue to hold em in place? I was thinkin of tryin somehting like this. Bought some LED bulbs, they suck, not bright at all.

also, how many do you think it would take to look nice and bright? and take it the wider the angel the better?

I was lookin at some of the 5 mm leds @ http://www.superbrightleds.com/leds.htm

[SophieSleeps]

So you use hot glue to hold em in place? I was thinkin of tryin somehting like this. Bought some LED bulbs, they suck, not bright at all.

also, how many do you think it would take to look nice and bright? and take it the wider the angel the better?

I was lookin at some of the 5 mm leds @ http://www.superbrightleds.com/leds.htm
I don't use hot glue to hold them in place. Hot glue prevents the leads from moving and shorting out.

I use superbrightleds.com LED's in 5mm.

[pennystocks]

So how do you get em to stay in place?

[SophieSleeps]

Depending on the surface, you can buy LED surface mount holders.
Do a radio shack search or something.