I DEFINITELY need orange LEDs and would like to have them as bright as I can and have the widest viewing angle that I can...I don't know where the happy medium between these two aspects are...any suggestions on a good online LED supplier?

 

You can check Mouser and Digikey. They have pretty good parametric search engines.

Why don't you tell us what your application is? It may be easier to use fewer but more powerful LEDs.

If you want a really wide viewing angle, you may need to go to surface mount LEDs.

 

I am building a table that is going to have LEDs coming in from the bottom and out through the top...the LEDs must be flush with the top...as in the table top must be smooth. I guess, now that I think about it, the only way you are going to be able to see the LEDs is if you are standing directly beside the table so the viewing angle might not matter that much.

 

Take a look at these:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=475-2486-1-ND
Size 0603 surface mount. 160 degree viewing angle. Under $9 for 100.

Surface mount that small will be kind of a pain to work with, but they won't make much of a bump.

 

Edit: Reverse polarity from the AC can be a bad idea for LEDS, since they often have low reverse breakdown voltages. If you are going with a regulated DC supply then that is what you should use for your test rig.

This is the type of setup I thought would work for checking LED's. I would hate to wire them up permanently without checking them first.

An extra few minutes to build the test rig and a few more to socket test each string and maybe swap out any LEDs that dim earlier than the rest when the variable resistor is used to drop the current.

Also wondering are these going to be on AC power or DC ?
You mentioned regulated which makes me think you are leaning to DC.

 

They will be powered using a 120V AC to 12V DC power supply...SgtWookie, I am leaning towards using the original 16 degree LEDs due to the fact that the project design will not allow viewing the LEDs from a very wide angle...any thoughts on this?

 

Potato Pudding: your idea would mean that the LEDs would have to endure reverse voltage, which is generally not a good idea.

An easy solution is to use an LM317 regulator and a single resistor. 43 Ohms from OUT to ADJ will give you a 29mA constant current source (from ADJ to GND) or sink (from +V to IN). You can then measure the Vf directly across the LED.

 

They will be powered using a 120V AC to 12V DC power supply...SgtWookie, I am leaning towards using the original 16 degree LEDs due to the fact that the project design will not allow viewing the LEDs from a very wide angle...any thoughts on this?

16 degrees is not much.

I'd opt for a wider view. You'd have to be hovering over the table to see them, and then they would be blindingly bright.

Note that staring at super-bright LEDs will cause permanent vision damage.

You may need to dim the LEDs using a PWM circuit. That would be easy enough to add at a later time, as long as the maximum current flow is taken care of up front.

 

haha...well I might try to find another type of 5mm orange LED then...I really would like to have the standard type of LEDs as opposed to the surface mount due to the fact that the table is completely built and was built to accomodate the standard type of LEDs...what viewing angle would you suggest?

 

30 degrees and 40 degrees are standard viewing angles for 5mm LEDs.

 

Most of the 5mm Orange LEDs I can find are 25° viewing angle...but I found some flat top 5mm LEDs on EBay that claim to have a 140°-180° viewing angle...I know you never really know what you will get from EBay but these sounded pretty interesting! Here is the link if you guys want to check them out!

http://cgi.ebay.com/50-5mm-FLAT-TOP...tem&pt=LH_DefaultDomain_0&hash=item35a0a91637

 

My cheap Chinese solar garden lights use flat-top LEDs with a 140 degrees viewing angle.

 

So are you trying to say I shouldn't use cheap Chinese flat top LEDs? haha

 

I have never purchased cheap Chinese LEDs and I have never purchased no-name-brand junk from E-Bay.

Instead I purchased many reliable high quality LEDs made by Hewlett-Packard, Fairchild and Philips Luxeon. I bought them from Digikey and Newark.

 

Lots of hobbyists make their purchases simply based on the color they want and the lowest price for the highest mcd rating. It's easy to inflate your MCD rating if you focus the LED very narrowly. Sure, the LED will be REALLY bright - but in a very narrowly focused cone.

If you really want to go with those cheap narrowly-focused orange LEDs, I suppose you could - but I'd suggest getting rid of the narrow focus by sanding the lenses down. They'll have a much wider viewing angle then. As an alternative, you could simply mix up some clear Lucite or other clear acrylic and pour it over the table after installing the LEDs (making certain that they all work first, of course) and that should eliminate the narrow focus - besides making a very durable table surface.

 

I believe I might try the flat top LEDs...the project is just for fun and I am really just experimenting with what I can do...so if the LEDs list a voltage drop of 1.8V-2.2V and a current rating of 24mA, how would I go about figuring out what size resistor I need?

Once again here is the link to the LEDs if you would like to take a look at the data sheet (well it is sort of a data sheet):

http://cgi.ebay.com/100-5mm-FLAT-TO...tem&pt=LH_DefaultDomain_0&hash=item3c9eb010c3

 

Use an LM317 as a constant current source. I suggest using one set up to put out 20mA, and don't use more current than that unless you like to see LEDs burn out early.

LM317 regulators are available at any Radio Shack.
To use one as a current regulator, you connect a resistor (see calculations below) from the OUT to the ADJ terminal. You can then connect an LED between the IN terminal and your +V supply with the ADJ pin grounded, or connect the LM317 IN pin to your +V supply, and connect your LED between the ADJ pin and ground - "ground" meaning your supply return.

Iout ~= 1.25/R, where R=.83 to 120
Conversely,
R ~= 1.25/DesiredCurrent, where 10mA <= DesiredCurrent <= 1.5A
If you use a 62 Ohm resistor for R, you will get very close to 20mA current flow through the LED.

Then measure the Vf of your LEDs. You could either do a statistical sample (randomly sample 10 LEDs and use the average voltage) or you could sample each and every one, then match them up to assure very even lighting.

 

So I should replace each resistor in the attached schematic with an LM317 + resistor combo? So in other words I need 12 LM317s and 12 62 Ohm resistors.

 

No, I didn't say that.

The LM317 + resistor is just to test the Vf of the LEDs.

That way you can either just test a statistic sample of them (say, 10 out of 100) or you could test them all, and quickly sort them out by their Vf, and match them up.

Use fixed resistors for the current limiting of each string.

 

I apologize....I forgot to attach the schematic. Here it is.