Dimming an LED? Just resistors or some other way?

One of the new LEDs I installed in my custom switchbox is... how do I say this?

It's friggin' brighter than the sun.

I noticed it right away the first time I fired it up at night and I thought I could deal with it, but man, it's almost distracting.

Shy of tearing the wiring open to install a resistor (which would impede a portopn of the current and, I ASSUME, dim the LED), is there perhaps a way to cut the light instead? I was thinking of maybe grinding down the lens at the end of the LED - I figure of the tip is flat and diffuse that might be easier on the eyes while still being visable in the day....

What have you guys done to dim your LEDs? Or, are you all just bright freaks?

Oh, if I do end up just putting in a resistor, how would I calculate, say, dimming it by around 50%?

ive found that putting 2 resistors in series will significantly dim the led.

altho im sure there is a better way.

This is a stab in the dark, I don't know **** but I want to try and use my brain and see if I'm right.

You can DIM LED's by giving them a lower voltage.

So, let's just say, you run a 3volt LED at 1.5 volts, you've dimmed it 50%.

Find out what type of resister gets you from 12volts to the 3volts. Then find one to get you from 12vlts to 1.5volts.

Am I kind of in the right direction?

i have mine hooked up to the interior dimmer control, works ok...wish it would go dimmer though

itzbjorn wrote:

So, let's just say, you run a 3volt LED at 1.5 volts, you've dimmed it 50%.

Yes reducing the voltage to the LED is a fine way to dim them. But you are wrong in saying that by cutting the voltage in half the brightness is also in half. They dont dim linearly like that.

You could also restrict current but I would suggest just adding a POT or another resistor in line (ground or positive) to reduce the brightness.

corvettecrazy wrote:

itzbjorn wrote: So, let's just say, you run a 3volt LED at 1.5 volts, you've dimmed it 50%. Yes reducing the voltage to the LED is a fine way to dim them. But you are wrong in saying that by cutting the voltage in half the brightness is also in half. They dont dim linearly like that. You could also restrict current but I would suggest just adding a POT or another resistor in line (ground or positive) to reduce the brightness.

Ah, that's what I was wondering... so how DO they dim, anyway? Does anyone have experience with resistor dimming and can make a recommendation as to what I might try? I'll be grindng down the LED tip in the morning and I'll see if that spreads the light enough to make dimming unnecessary, but I'm thinking I;ll need to cut the light at least a bit in the end...

Thanks!

Could always get some of that stuff they spray on to brakelight covers to get em darker.. Ghetto rigging's always easier

Buy some film and tint them!

I'd recommend picking up a couple of these little preset variable resistors (potentiometers) from an electronics store (radio shack or something). These are handy but be careful not to turn the resistance too low or you'll let the smoke out of the LED . As long as it's accessible you can keep adjusting it over the course of a few nights until you get it just right, and if you want to turn it up for oooo's and aaaaah's some night your have the power. Once you find the setting you like you can mesure the resistance with an ohm meter and then you'll know what kind of simple resistor to buy if you want the same fixed resistance in the future. It's nice to have a spare one of these for testing.

http://www.fastcomponents.co.uk/product_info.php?products_id=61

That's not a bad idea, actually... Any reason why I couldn't just set it like I want and then leave the tiny pot in the switch box housing?

I ended up grinding down the tip and then used some transparent black INK (used for shading mminiatures) on it... Doing so had a dual benefit - it toned down the glare considerably and it also "stealthed" the LED - now it just looks like a round black nub until it's lit up, which is pretty nice - un-inked the LED was white and very visable. I worry about pulling off the ink over time as I clean the box with a microfiber cloth, though, so a more permament solution would be better...

Thanks Cyber Knight!

ImagoX wrote:

That's not a bad idea, actually... Any reason why I couldn't just set it like I want and then leave the tiny pot in the switch box housing? Thanks Cyber Knight!

No reason at all, that would work fine. And you're welcome