Differences b/w different LED s

Hi, some of you may remember me asking some help with possible wiring of LEDs for custom motorcycle turn signals. I'm still not sure how exactly to wire it and what resistance, but what the hell, I'm ready to experiment. I see all different kinds of sizes and such (I think I'm going to stay away from Luxeons, they seem more complicated, and more expensive if I dont' get it right), but don't know what to get. The price ranges a lot, and I have to ask myself if I "get what I pay for". I ask this now because I found a bag of:

"T1¾ (5mm) Amber Flangeless Dome Discrete LEDs (1,000 in pkg.)"

for 20 bucks. Seems to cheap to be any good. Are they not bright? I don't know. What do you all think about this?

Here's the addy of the place I saw them

http://www.surplusled.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=S&Category_Code=_DL_5mm

Do you guys not like helping people that don't know much about this? Believe me, I'm not complaining, but this is the second post that didn't really help me out any. Everyone here seems to know their stuff, and this seems like a simple answer to those that are in the know. I'm not trying to bother you with seemingly simple questions, but I don't know where to find simple answers like these. It seems easier to have someone experienced in these type of things to fill me in vs. reading article after article and still be left with questions that need answered.

If you don't know about the particular LEDs I posted about, could you direct me to some that are priced decent and put out the best amount of light for my needs?

2wheeledslave,

Welcome to CPF! Solid state lighting is what this sub board is about! Your application is dear to the hearts of many here! There are Amber luxeons approaching 150 Lumens coming on the scene, but they require ~3V and a motorcycle's 12V power is very dirty.

You are not on a simple quest. The electronics guys on the electronics/batteries-included forum will be happy to try and out do each other for the *best* circuitry for your application. The LED general board members will argue endlessley as to what color bin you should use. /ubbthreads/images/graemlins/crackup.gif

The answers are here on CPF, but it will take some time for you to "pry them out." Welcome again!

Larry

Thanks for the reply and the welcome, when you say the voltage is dirty, do you mean that it's basically far from steady?

So you think I should try my luck in the forum you mentioned intead?

I have done a simple LED Mod to my bike's turn signal & brake lights....

have a look... at This thread

Some of the Questions that i had that time are quoted below.... you will have to go through the whole thread to see the details & responses to my questions...

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ViReN said:
Hello All,

First of all consider following schematics
Schema 1


Schema 2


The above two are two possible configurations for my car vanity mirror light. The battery source is having a constant voltage of 12 Volts. I am connecting a series parallel combination of 3 LED's in series and 6 such rows connected in parallel making total of 18 LED's. The desired LED Current is 30 mA and VF is 3.8 Volts (slightly overdriving LED's). I do not intend to make use of Buck Regulators, as there are space restrictions. Out of above two, which configuration is best? And why?

Also, do you think using Buck Regulator & a Sense Resistor (for current limiting) make things any better?

As always, Your suggestions and comments are most valuable to me.

Thanks & Regards
ViReN

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[ QUOTE ]
ViReN said:
Hey All....

Its DONE /ubbthreads/images/graemlins/smile.gif Here are the details....

I did experiment with different values of resistors and at different supply voltages .... I also checked what voltage do I get at the Battery Terminals (about 16 !!!) and at the Light Connection Point (about 11.9 when car is off... and goes up to 13 when the car is on almost near full throttle.... actually the voltage changes first up to 13.5 and then drops near full throttle, must be some sort of internal regulation inside the car's circuit). So... I used a 39 Ohm's Resistor 1/8th watt. 1/8th watt instead of 1/4th ... please note this. Its a Metal Oxide resistor. So in worst case, the resistor will blow off... saving the LED's. I also measured current through one row and it was at max of 36-37 mA @ 15 Volts .... (the resistors did the job of keeping the current down.... though they got a lil warm... but did not blow off or any thing like that and that too for about 4-5 Minutes... I guess this much time is enough for it to settle down)....

Using Luxeon's is out of question as for now, because they are costly. For me the total cost of project was very very economical.
Here's the maths...
-->Cheap (Hong Kong) 10,000 mcd LED's 18 @ $0.2 (each) = $ 3.6 (these LED's are not as bright as Nichia's but they definately are brighter than most of other LED's in market). If i had to use Nichia's ... to get the same output... i would have required atleast 9 LED's .
-->Resistors 1/8 Watt, Metal Oxide 20 @ $0.2 (total) = $ 0.2
-->Cost for PCB Making 1 @ $ 1 = $ 1

-->Total cost of project = $ 4.8

.... and i guess a Simple photon costs $ 15 isnt it ? of course... it has ton's of functions... but the bottom line is.... you get the whole light modified under $5 and its really worth.

If ever I have to sell these PCB's with LED's .... i think i will take additional $ 1 (adding towards man power expences) .... Shipping charges extra ofcourse /ubbthreads/images/graemlins/smile.gif ... so the total cost for buyers will be $ 5.8 + Shipping...

Ok... Much said.... Here are the Pictures
Note: forgive me for bad picture quality... they are captured from my mobile... as i was lazy to capture em with my digi cam...
Pic 1 - The Internal, Lights off, showing the layout


Pic 2 - The Internal, Lights on (these lights are not throwing any direct light (beam) to the camera lense... if i try to capture like that... all that you see is just a corona of light... every thing else is DARK)


Pic 3 - The Exteriors, Lights on and with light cover put on


Please note that the Light is evenly distributed after putting on the light cover (which is a soft light diffuser) and ofcourse... very bright pure white (slightly bluish tinge) light.

Please Comment about the things.

I must thank to every one who has contributed towards this. Special Mentions to Steelwolf /ubbthreads/images/graemlins/smile.gif

Thanks & Regards,
ViReN

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[ QUOTE ]
ViReN said:
Hi again....

Just fixed the lights .... here are the pictures....

Pic 1: The brake Light console(upper one) (also note small twin cluster lights below(lower one)) All LED's ... and the blueish lights on the number plate are in fact WHITE lights... appearing blue as compared with the red ones... or may be its just because of my mobile's camera ... the camera is not recieving direct light... it is taken from an angle....


Pic 2: Yeah... thats what happens when they are directly pointing towards the camera lense... in fact its a cluster of Amber & Red-Orange LED's ... and the fact is that they are REALLY Bright


Pic 3: This one i guess is a proper picture to show relative light Output ... note this time.. its not directly pointing towards the lense


Hope you like it...

Best Wishes,
ViReN

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it actually started as a car vanity light... ended up in modifying bike too /ubbthreads/images/graemlins/smile.gif

Wow, thanks so much, I'll have to go through that thread later, but from what I've skimmed through so far, it will help me out a bunch.

Again, any and all suggestions are very, very welcome!