Resistors & LEDS & Buttons oh My!

[Brad Lee]

Are resistors reversible? Meaning are they like diodes that would limit current one way and not the other? Or can they be conencted either way

Also, are 220k 1/4watt the correct size to go between a +5v power supply and a 2.2v LED? Thats the number that keeps popping into my head from reading earlier posts but I can't find anything right now

[PacManFan]

Resistors can be used either way, they do not act like diodes.
I think you need a resistor in the range of 1k - 3k . Anything beyond that will be too dim.
-PacManFan

[radiator]

pretty sure a resistor can be mounted either way...

...not sure about the value for a 2.2v LED though (off the top of my head anyway)

try a search in google for a resistor calculator

[Birdtales]

Here are two resistor calculators....

http://members.cox.net/brutal/Resistor/main.html

http://www.bit-tech.net/article/68/

[seaner]

resistors will resist current flow in either direction.
To determine the size of resistor you require, you need to know how much current the LED draws.

current = Votage/Resistance

so if your led need 5mA, for example, 1K ohm would do the trick.

[Brad Lee]

Found it-
http://www.ultimarc.com/ipac2.html
at the bottom of this page is the diagram for leds to an Ipac, so thats where i kept finding the 220 resistors

I will check my switches when I get home for the draw needed and use one of those calcs to figure out theright one

Thanks

[ErikRuud]

Note that the Ultimarc diagram actually shows 220 Ohm resistors, not 220K ohm resistors.

[Carsten Carlos]

The resistors depends on the color and brightness of the LED you wanna use.

Check my homepage under "LED's how to", there is a table of the most common colors and which resistor they need at 5V.

[seaner]

The resistors depends on the color and brightness of the LED you wanna use.

That's a bit of a broad statement which may hold true for one family of LEDs.  Some LEDs require much more current than others, regardless of the color.

[Brad Lee]

Note that the Ultimarc diagram actually shows 220 Ohm resistors, not 220K ohm resistors.

Yeah that was my bad, just took a quick look at it and typed it later..

Well according to the calculator it should be either a 300 or 330ohm

The switches are straight off of a Midway panel and are labeled like this:

+=2V MAX
10A 125/250VAC

[Carsten Carlos]

That's a bit of a broad statement which may hold true for one family of LEDs.  Some LEDs require much more current than others, regardless of the color.

Of course it is, but if you would have visited the site I mentioned you would have found found much more explanations regarding this and how to calculate it correctly.

I don't wanted to retype this all here - this is were my page is for. Everything there.

Also, notice I wrote color and brightness! Basically you can work with this if you've no idea how much current your superbrightness-LED would need.