i need to wire up some leds.. and no they arnt for ricer purposes so dont bother talking ****.. but i heard youneed to run resistors or something on them? ive never wired them up before but i need to now. and does radio shack sell them?

 

Depends on the LED. If they're a straight 12v LED, then no resistors should be required.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drunknbass &raquo;</TD></TR><TR><TD CLASS="quote">i need to wire up some leds.. and no they arnt for ricer purposes so dont bother talking ****.. but i heard youneed to run resistors or something on them? ive never wired them up before but i need to now. and does radio shack sell them?</TD></TR></TABLE>

yeah, we need to know what kind of LEDs you are working with.

 

things you need to know.

1. What voltage are they designed to be run at.
2. What is the rated current of the LED.

I hope anyone that tells you to use a resistor is calculating the resistance using 14.4 volts. If its done at 12 your LED wont last long.

A voltage regulator would be a better choice.

 

If it's a 15-20mA LED (most common) then about 1kOhm

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxxtreme &raquo;</TD></TR><TR><TD CLASS="quote">things you need to know.
1. What voltage are they designed to be run at.
</TD></TR></TABLE>

It's not a bulb, it's a diode. Diods don't run at certain voltage, but at their nominal current

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Olegus &raquo;</TD></TR><TR><TD CLASS="quote">If it's a 15-20mA LED (most common) then about 1kOhm

It's not a bulb, it's a diode. Diods don't run at certain voltage, but at their nominal current </TD></TR></TABLE>LOL so if I hook up an Alpine 3 volt led to the cars 12 volt it will last longer then one nano sec. 94

 

i dunno.. the radio shack ones are easiest to get but they are like 2.2 volt or something i dunno.
i saw some at frys that are 12v so maybe thats better to get?
im not used to wiring these things up so i have no idea what the techy **** means. i just need them to work haha

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drunknbass &raquo;</TD></TR><TR><TD CLASS="quote">i dunno.. the radio shack ones are easiest to get but they are like 2.2 volt or something i dunno.
i saw some at frys that are 12v so maybe thats better to get?
im not used to wiring these things up so i have no idea what the techy **** means. i just need them to work haha</TD></TR></TABLE>
things you need to know.
1. What voltage are they designed to be run at.
2. What is the rated current of the LED.

A 12 volt LED will still burn out if used in a car.

LED's work the same as a normal diodes with a higher turn on voltage. The voltage across them will be the turn on voltage of the LED. The point of the resistor is to limit the current through them. Which is why your supposed to calculate for worst case, which would be at 14.4V. The LED will be dimmer at 12v but will still operate safely at 14.4 if you calculate for worst case.

Go buy the LED's you want and report back the questions I asked. If you buy them from radio shack the information should be on the back of the package.

There are no "common" LED's they come in a variety of voltages and currents. For example if you go on http://www.digikey.com you will find over 3000 different LED's.

If you used a 2.1 volt LED and took into account worst case conditions 14.4 volt supply, and using your 1k resistor. You would have (14.4-2.1)/1000=12.3mA Which would be safe for your application because the max spec from your information is 20mA.

If you used a 1.2V LED that had a max current spec of 10mA. It would burn out over time, it would still function but outside its spec. (14.4-1.2)/1000=13.2mA This resistor would need to be changed to limit the current throught the diode if you wanted it to last.




Modified by nsxxtreme at 10:59 AM 2/22/2005

 

any update on this did you find your diode?

 

http://www.lunaraccents.com/project%20elements.htm

 

this is what i just got today.. it looks like its made for 12v dc current so i think it should be ok for my cars electrical.
heres a pic of the back of the box

i think they just show you what to hook the + and - to, but i dont get what all the ohm **** means. looks like if i wire it to a diff voltge i have to do something but i think im fine?
also the only blue led i could find had a sticker that said 3.5 candella on it, and another big orange sticker that said dont stare are led it will damage your eyes. so im thinking this is an extra bright one and candela stands for how bright it is?

 

Don't know why you would waste the money on that but hope it fits your needs.

You could have purchased just about any LED and it would have worked in your car.

THose have to be some of the worst intructions or data I have seen. Do you even know what the viewing angle is?

 

First of all, sticking a fat resistor on a +12 isnt the greatest thing to do, there is a good chance you will STILL fry your led. Look up LM317 voltage regulators. They can give you a SOLID output nomatter the input voltage ( as long as its 1.5v more than what you are out putting, and less than 37v) Also, if you did want to just to a resistor, use this equation (Vs-VL)/IL= R(in ohms) Vs= Source voltage (in DC) VL= voltage required for the led, IL= current the LED requires.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Olegus &raquo;</TD></TR><TR><TD CLASS="quote">If it's a 15-20mA LED (most common) then about 1kOhm

It's not a bulb, it's a diode. Diods don't run at certain voltage, but at their nominal current </TD></TR></TABLE>

actually, LEDs do have a voltage requirement, usually between 1.7 to 3.5. And yes, they do require a current, but they will only draw as much current as they need. You can definately drive LEDs using voltage regulators and using a specific voltage.


Also, you need to research LEDs more. Candela is how much light is emitted. LEDs are usually measured in mcd. It looks like from that package you bought a rectifier diode, which is not what you want.