Question for LED experts

JByron · 10-10-2006, 12:50 AM

I'm looking for really flat and really bright red led's to do an illuminated door sills project. Can anyone recommend any stores or products?

Here's a picture of the underside of my doorsills so you get an idea of the limitations in space I'll be working with.

HighVoltage · 10-10-2006, 01:00 AM

www.digikey.com
www.mouser.com

What kind of look are you going for?

sillieidiot · 10-10-2006, 01:16 AM

www.superbrightleds.com

JByron · 10-10-2006, 01:29 AM

Quote:

Originally Posted by HighVoltage

www.digikey.com
www.mouser.com

What kind of look are you going for?

I'll be illuminating the lettering on the other side that says RSX. I plan to cut out the plastic and replace it with a transparent material, and light it an even red glow that matches the interior lighting. I want it to fade on when the door opens and off when I close it.

Any electrical expertise would be much appreciated as well. I'm guessing a system of resistors will be needed, and I'll have to tap into the dome light power wire?

sillieidiot · 10-10-2006, 01:41 AM

just go to the site i posted and click the hobby section. should give you some basic info for what you're doing i guess. hope it helps.

HighVoltage · 10-10-2006, 01:54 AM

Multiple leds with a resistor array is one approach. Sizing shouldnt be too much of an issue as you can get them down at least as far as 0603 but I imagine you would be more comfortable working with a size like T1. There's always fiber optic too...In either case I would look for some superbrite ~630-660nm (red) leds as your starting point.

JByron · 10-10-2006, 02:21 AM

Quote:

Originally Posted by HighVoltage

Multiple leds with a resistor array is one approach. Sizing shouldnt be too much of an issue as you can get them down at least as far as 0603 but I imagine you would be more comfortable working with a size like T1. There's always fiber optic too...In either case I would look for some superbrite ~630-660nm (red) leds as your starting point.

http://www.ledtronics.com/ds/BP121/

are these the ones you mean? how bright is 50mcd? I'm afraid that an array wouldn't provide an even glow, but rather several red dots

or are these better?
http://www.ledtronics.com/ds/L200-0UR/

HighVoltage · 10-10-2006, 09:07 AM

The "brightness" of an led can be somewhat ambigious given each person has their own opinion on what is "bright". To me, 50 millicandelas (mcd) is not very bright at all. I would look for something at least 250mcd if not 1000mcd+. The problem, is that typcially the higher the mcd output the larger the led. Also keep in mind they typically list figures at nominal levels. You may end driving the led a little higher or lower depending on the source voltage. You will need to current limit the led with a resistor with respect to your source voltage (i.e 12V - 14V). The current draw is proportional to the limiting resistor and (not quite linear though) to the mcd. You usually have to comprise between the "perfect" resistor value and what is available.

I would suggest going down to your local electronics store and pick up a led or two, calculate the resistor value you will need (we can help) and judge the brightness for yourself. I would also make a template out of something like cardboard of the doorsill with your intended cuts. This way you can experiment with different leds until you get the look you are after.

HighVoltage · 10-10-2006, 09:27 AM

One other small thing....you should keep on eye on the full or viewable angle listed too. Some leds put out large mcd ratings but are coupled with very tight (small) angles. What this boils down to, is that the light intesity has a sharp drop off as viewing angle deviates from the orthoganal with respect to the led base. So if your are not looking straight at the led with it right in front of you, you may not see much light (look very dull).

There are quite a few sites out there that explain leds. Here is nice and simple example: http://www.kpsec.freeuk.com/components/led.htm

10-10-2006, 12:50 AM	#1
JByron Registered User Join Date: Nov 2002 Location: Los Angeles, CA Posts: 696 My Ride: Two-wheeled unicycle View My Garage	Question for LED experts I'm looking for really flat and really bright red led's to do an illuminated door sills project. Can anyone recommend any stores or products? Here's a picture of the underside of my doorsills so you get an idea of the limitations in space I'll be working with. __________________ So-Cal Sig Size Compliance Society: Now Less Than 800 pixels!

10-10-2006, 01:00 AM	#2
HighVoltage Registered User Join Date: Sep 2006 Location: TX Posts: 431 My Ride: 2007 335i View My Garage	www.digikey.com www.mouser.com What kind of look are you going for? Last edited by HighVoltage; 10-10-2006 at 01:04 AM.

10-10-2006, 09:07 AM	#8
HighVoltage Registered User Join Date: Sep 2006 Location: TX Posts: 431 My Ride: 2007 335i View My Garage	The "brightness" of an led can be somewhat ambigious given each person has their own opinion on what is "bright". To me, 50 millicandelas (mcd) is not very bright at all. I would look for something at least 250mcd if not 1000mcd+. The problem, is that typcially the higher the mcd output the larger the led. Also keep in mind they typically list figures at nominal levels. You may end driving the led a little higher or lower depending on the source voltage. You will need to current limit the led with a resistor with respect to your source voltage (i.e 12V - 14V). The current draw is proportional to the limiting resistor and (not quite linear though) to the mcd. You usually have to comprise between the "perfect" resistor value and what is available. I would suggest going down to your local electronics store and pick up a led or two, calculate the resistor value you will need (we can help) and judge the brightness for yourself. I would also make a template out of something like cardboard of the doorsill with your intended cuts. This way you can experiment with different leds until you get the look you are after. Last edited by HighVoltage; 10-10-2006 at 09:10 AM.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode	Rate This Thread:

10-10-2006, 01:16 AM	#3
sillieidiot Registered User Join Date: Sep 2004 Location: the OC Posts: 43,390 My Ride: '06 AW 330ci View My Garage	www.superbrightleds.com

10-10-2006, 01:41 AM	#5
sillieidiot Registered User Join Date: Sep 2004 Location: the OC Posts: 43,390 My Ride: '06 AW 330ci View My Garage	just go to the site i posted and click the hobby section. should give you some basic info for what you're doing i guess. hope it helps.

10-10-2006, 01:54 AM	#6
HighVoltage Registered User Join Date: Sep 2006 Location: TX Posts: 431 My Ride: 2007 335i View My Garage	Multiple leds with a resistor array is one approach. Sizing shouldnt be too much of an issue as you can get them down at least as far as 0603 but I imagine you would be more comfortable working with a size like T1. There's always fiber optic too...In either case I would look for some superbrite ~630-660nm (red) leds as your starting point.

10-10-2006, 09:27 AM	#9
HighVoltage Registered User Join Date: Sep 2006 Location: TX Posts: 431 My Ride: 2007 335i View My Garage	One other small thing....you should keep on eye on the full or viewable angle listed too. Some leds put out large mcd ratings but are coupled with very tight (small) angles. What this boils down to, is that the light intesity has a sharp drop off as viewing angle deviates from the orthoganal with respect to the led base. So if your are not looking straight at the led with it right in front of you, you may not see much light (look very dull). There are quite a few sites out there that explain leds. Here is nice and simple example: http://www.kpsec.freeuk.com/components/led.htm