resistor chart vs. luxeon calculator?

[djbordie]

oya,

so the resistor chart here shows a cyan 5w with a 7.2 to use a 1watt 1ohm resistor...yet the luxeon calculator says to use 1/4watt 1ohm resistor....

what will be the difference here?

for saber purpose which should be used...i only understand that a lower watt resistor will allow more power through, and this may not be a great idea? [please explain.

thanks,

-dave

[supertrogdor]

as i understand it, the chart takes those measurements and ups your resistor to the next most readily available item. It is likely possible to find a 1/4 watt resistor, but it is easier to find a 1 watt, and it will not damage your LED to run it that way. You can always count on Tim's information. If he posts it on his site, he is certain it will work.

[djbordie]

ahhh excellent, cheers thats what i wanted...safety first

[djbordie]

http://www.thesourcecc.com/estore/category.aspx?language=en-CA&catalog=Online&category=Resistors&pagenum=1&sort=1
heres what radio shack has, they have that 1/4watt 1 ohm, which is suggested by luxeon calculator, but they dont have a 1 watt 1 ohm, will anything else here work? like maybe 1watt and more ohms...i dont know about ohms...

[Steeljack]

like maybe 1watt and more ohms...i dont know about ohms...

Ohms are a measure of resistance -- how much something resists the free flow of current. The worse a conductor of electricity something is, the higher its resistance. The better a conductor it is, the lower its resistance. (It follows that a superconductor, for instance, has a resistance of 0 Ohms.)

Wattage is a measure of power-dissipation capacity. Running a current through a resistor -- through any non-perfect conductor, really -- produces heat. If you generate more heat than the resistor and its packaging can handle, you're likely to damage some part of your circuit, starting with the resistor.

It's generally safe to use a higher-wattage resistor in place of a lower one. The reverse is not true. Why not use the highest-wattage resistor you can find, then? Well, because resistors get larger and bulkier as their wattage goes up, and space inside a saber hilt is always at a premium.

One thing you can do if you can't find a resistor with the exact characteristics you want is combine the ones you do have on hand in different ways.

The resistance of resistors in series is additive: two 2-Ohm resistors in series act like one 4-Ohm resistor.

Placing resistors in parallel, on the other hand, divides their total resistance: two 2-Ohm resistors in parallel act like one 1-Ohm resistor.

This doesn't seem terribly useful until you realize that power dissipation always adds up. So two 1/4-Watt 2-Ohm resistors in parallel behave like one 1-Ohm resistor, but that resistor can handle 1/2 Watt.

Getting back to your original question, 1 Watt and more Ohms would give you a dimmer LED, because you'd be introducing more resistance into the circuit than necessary. You'd want to get lower resistances, and put them in series, or higher resistances and put them in parallel, to get the resistance you need and a power-dissipation capacity you're comfortable with.

[Hasid Lafre]

Hay thats pritty good.

I vote to have something like this for the beginners to read so they got a better understanding of resistors.

[Strydur]

It pretty much explains that at the bottom of the resitor page.

It is better to use a higher wattage rated resistor than required, but never use a resistor at less than 25% of its rated power.
The resistors listed above are the recommended or better wattage rated resistor for each specific voltage/LED combination.

[goldsaberwarrior]

If I may ammuse you all for a moment.
The resistor is the heart of the hilt.
The hilt is the holder of the blade.
The blade is the inflictor of defeat on the enemy.
The defeat of the enemy is the goal of all saber wielders.
All are intertwined, the resistor, the hilt, the blade, the defeat, the enemy.
It is all one.

Just something I came up with out of the blue. :lol:

[Novastar]

Screw resistors. Use a driver board. Way better.

'Nuff said.