LED Project: Need help to identify components

[eugenemon]

Sorry for being unclear in my objectives. I've deleted the previous posts to not confuse anyone.

Let's call this LED A (I do not have it)


And this LED B (I have it)


My purpose: To replace my car's original parking lights (which currently uses a filament bulb of 5W) with a white LED. I want to know the components to build LED A.

Why: Because when I plug in LED B, LED B would flash only once in awhile. (this would trigger an error on my on board computer saying my bulb has blown and i need to replace it.) I've tried LED B with a 5W 100ohm ceramic resistor and it works (no error) but is troublesome because it requires me to attach the resistor which is big and bulky. I want a simple plug and play LED like LED A. It is proven that LED A works without anything like resistor or what attached. So I want to try to make it.

Now that you tell me LED A has a constant current driver, does that mean the on board computer on my car measures the current (amps) and not the watts of the bulb to sense the error?

Currently, I know on LED A there are:

-2x LED (1 back and 1 front)
-2x 150ohm SMD resistors
-1x 270ohm SMD resistors
-1x unknown SOT-23 (the one circled in red, appears to be a transistor)
-2x unknown value small resistors (circled in pink)

What other information you need please let me know. Thank you guys!

[eugenemon]

Ok, another question. If i used high power 5w luxeon leds like this:



http://www.led-tech.de/en/High-Power-LEDs-Luxeon/Luxeon-5W/Luxeon-5W-Star-LED-LT-620_49_43.html

Does it mean that its power output is equivalent to a 5w filament bulb when connected to a 12v DC battery?

[minimum]

I have to maintain the output power around 3 to 5W so there will not be any error.

Why? Is it replacement for turn signal? In that case, it's better to replace the turn signal relay.

Which also means incorporating the 5W 100ohm resistor into that 1W led.

Very bad idea. The resistor will heat up and will reduce the life of LED drastically.

How to put a 5W 100 ohm resistor into ...

You can't. If you need to maintain the load in the circuit, mount the resistor elsewhere, in parallel to the rest of the LED circuit.

[minimum]

Does it mean that its power output is equivalent to a 5w filament bulb when connected to a 12v DC battery?

First, you cannot connect bare LED directly to power source. You will get only one, very brief flash. There should be a circuit which limits current.

By power output you mean emitted light?
5W filament bulb has efficacy around 8-10 lm/W. The 5W Luxeon on the other hand about 40-50 lm/W. So you will compare 40-50 lm to 200-250 lm in total. All that if comparing white LED to white (not filtered) filament.

[cadstarsucks]

Does it mean that its power output is equivalent to a 5w filament bulb when connected to a 12v DC battery?

First, you cannot connect bare LED directly to power source. You will get only one, very brief flash. There should be a circuit which limits current.

By power output you mean emitted light?
5W filament bulb has efficacy around 8-10 lm/W. The 5W Luxeon on the other hand about 40-50 lm/W. So you will compare 40-50 lm to 200-250 lm in total. All that if comparing white LED to white (not filtered) filament.

And it is 250Lm all in one direction which makes it much brighter on your work area ... unfortunately it also drifts down in Lm/W with increasing current and temperature.  Typically a 30% drop going from 1W (you need to check how they are speced...often Lm/W is speced at 1W while the Lm rating is speced at 5W) to full power and a 50% or more drop as you reach max junction temperature.

[cadstarsucks]

Ok, another question. If i used high power 5w luxeon leds like this:
http://www.led-tech.de/en/High-Power-LEDs-Luxeon/Luxeon-5W/Luxeon-5W-Star-LED-LT-620_49_43.html

Does it mean that its power output is equivalent to a 5w filament bulb when connected to a 12v DC battery?

No.  First you need to understand the REAL data sheet: http://www.philipslumileds.com/pdfs/DS40.pdf

Which states 87Lm minimum and 120Lm typical for 700mA @ 6.84V or 4.8W.  With a realistic heat sink of 10C/W and added to the package thermal resistance of 11C/W at an ambient of 30C you will be down 30% to 61Lm minimum or 12Lm/W.  That LED, regardless of what some idiot salesman might tell you is among the worst examples of LED efficiency there is.  On top of that it does not even give lumen maintenance figures for this operation: at 85C heat sink temperature (at the emitter) it shows lists it as being down to 65% at only 600mA or 40Lm after only 500 hours!

the http://www.led-tech.de/en/High-Power-LEDs-Luxeon/Luxeon-REBEL/Luxeon-REBEL-on-star-LT-1411_49_85.html on the other hand...

is 160Lm at 2.5W, 95% for temperature and 80% after 20KHrs for 150Lm @ 61Lm/W at 500 hrs and 122Lm after 20Khrs

[eugenemon]

All right, since it's so troublesome with all the heating and all, I'll abandon the previous project. Now, I'm trying to find out what are the components on this led. This led has prove to work like what i need in the previous project. I believe with the same electric component and values, I can get it to work.

Currently, I know on this led there are:



-2x LED (1 back and 1 front)
-2x 150ohm SMD resistors
-1x 270ohm SMD resistors
-1x unknown SOT-23 (the one circled in red, I'm currently researching on what this is. appears to be a transistor)
-2x unknown value small resistors (circled in pink)

My head is bursting.   Help please guys!

[justDIY]

those components form a very simple constant-current driver for the LED.  It's one step better than using a dumb resistor alone.  Voltage across one (or both) of the big resistors controls the amount of current the transistor passes.  The transistor takes excess voltage and burns it off as heat.  The small resistors or maybe a resistor and cap help to bias the gate of the transistor to keep it in a safe working range.

this setup still won't handle a high voltage load-dump very well, and it is anything but efficient.

[cadstarsucks]

What are you trying to do?  Maintain light output or power input?  And why?  Just for the reliability?

Something is just not adding up...  For the same light output you can run at around a tenth the power.  The only circuits in a car that might cease to function are the flaky turn signal circuits that used to work by using the current draw to heat a bimetallic arm for the flash function, but I did not think those stupid things had been on cars for many years.

I would recommend a small switcher if you are up to wiring it.  The rebel I recommended would only need 175mA to put out as much light as that stupid bulb, and at a half a watt it is real easy to get rid of the heat.

You also neglected to mention what the actual purpose is... generally that means white lighting LEDs to us.  Your comments about needing the power to be the same would indicate otherwise.  You can not, in general, put LEDs behind filters since they usually will not match well enough for good results.

[eugenemon]

Sorry for being unclear in my objectives. I will explain it clearly now.

Let's call this LED A (I do not have it)


And this LED B (I have it)


My purpose: To replace my car's original parking lights (which currently uses a filament bulb of 5W) to a white LED. I want to know the components to build LED A.

Why: Because when I plug in LED B, LED B would flash only once in awhile. (this would trigger an error on my on board computer saying my bulb has blown and i need to replace it.) I've tried LED B with a 5W 100ohm ceramic resistor and it works (no error) but is troublesome because it requires me to attach the resistor which is big and bulky. I want a simple plug and play LED like LED A. It is proven that LED A works without anything like resistor or what attached. So I want to try to make it.

Now that you tell me LED A has a constant current driver, does that mean the on board computer on my car measures the current (amps) and not the watts of the bulb to sense the error? I just need them to handle the car's 12V battery.

What other information you need please let me know. Thank you guys!

[cadstarsucks]

you do one of three things:

1. hotwire the computer to fool it into thinking that the normal bulb is there

2. figure out what load (resistor) you need to tack on to fool it

3. get it to to a real modern day gear head that can edit the constants in the car's computer so it will work properly with the LED load

[eugenemon]

Yes, so now i know LED A can fool the computer. So can anyone tell me how to calculate so I can know the value of the resistors beside the transistor. Thanks.

[cadstarsucks]

Yes, so now i know LED A can fool the computer. So can anyone tell me how to calculate so I can know the value of the resistors beside the transistor. Thanks.

150 and 270 ohm