LED lamp creating considration

LED lamp Making Criteria

Hi experts ,
I like to make LED lamps
what is the consideration of making LED lamps ?
it means the ,
whcih types of LED need to be use ?
how can design the driving circuits ?
How can calculate the luminosity / Light ( the Lamp for a room)
please help me


thanks in advance

Some links:

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Lux - Wikipedia, the free encyclopedia
Lumen (unit) - Wikipedia, the free encyclopedia
Candela - Wikipedia, the free encyclopedia
Luminous efficacy - Wikipedia, the free encyclopedia
Light-emitting diode - Wikipedia, the free encyclopedia
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LED Driver ICs - Linear Technology
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LED Lights & Accessories - SUPER BRIGHT LEDS
CREE | LEDs for the LED Lighting Revolution
Nichia Corporation
Kingbright USA, an opto-electronic LED manufacturer products include all type of LED LAMPS , SMT LED, SMD LED, LED DISPLAYS optoelectronic components
LUXEON High Power LED Lighting | Philips Lumileds Lighting Company
LEDtronics | LED, LED Lights, LED Light Bulbs, LED Lamps, LED Indicators, Super Bright LEDs
LED : LEDs : LED Drivers : Cree LEDs : Luxeon LEDs : LUXdrive : LEDSupply
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http://ww1.microchip.com/downloads/en/AppNotes/00954A.pdf

Re: LED lamp Making Criteria

I've been making my own LED lights for a while and found el-cheapo retailers from Hongkong like DealExtreme.com has been very helpful. There are plenty around of course, but this one is a good one stop shop, from bulb housing, drivers, cheap CREE LEDs, etc etc.

One thing though, no manufacturer has compact current source yet (that is above 4W) that can fit into a bulb housing. After reading lots of info from these experts (regarding SMPS) in this forum, I definitely take these LED drivers for granted. I mean, when I first make my own power supply, it weighs 2-3 kilos and only produces 15W with a size of couple of bricks!!

[Added later:]

Oh, I found this case study from CREE is very helpful:
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First the most important is the LED that you will use. And second is the heating of the LED, you must control.
Third, the source mut be a voltage controlled, current controlled source. ANd does'nt mather if it is a linear or switching source.
Fourth is the dimming control.

hai ,miguel .can you explain each one you said .how can i ?

Ok you must select the LED that you want use.
Like colour lumens. From the datasheet you must select the operation current of the diode.
I'm using a 700 mA diode DS601.
You must build the current source, I recomend you a MOSFET.
Design of the current sensor . . . it is a Resistor and by ohm LAW I=V/R.
then the control circuit in order to control the current.
The reference voltage that tha control circuit will use.
At last the Voltage source.

According to my opinion one of the defining features of LEDs is that they emit light in a specific direction. Since directional lighting reduces the need for reflectors and diffusers that can trap light, well-designed led fixtures can deliver light efficiently to the intended location.

Re: LED lamp Making Criteria

Please consider the LED is working by current not by voltage. So if you drive LED by current source it is the best driver. Supply enough current at rating level to have maximum light.
Generally, the LED will be derived by Voltage Source + Resistor, this method is not recommended for LED lighting, due to its light is not constant & the life time of LED will decrease dramatically by voltage fluctuation.
The last thing to be considered is heat dissipation.

Why you are saying not voltage ,it use current i haven't tooo theory knowledge
the voltage and current (in Led) what you mean ?
please explain ?

LED is a diode. The voltage of diode is constant that called Vf (Forward voltage). So theoretically, it is not possible to connect an LED to voltage source.
So we need always a resistor series with voltage source to limit the current.
Suppose the Vf of an LED is 3 volt. How is it possible to connect it to a 5v voltage source!? But when we add a resistor to our circuit it will generate current, now we should select proper resistance to limit current to meet rating of LED.

We can see this subject from other view point, if you have an LED, you need to know what the current rating is. When you apply this current to LED, It will be on perfectly. And you don’t need to know anything about voltage of LED in this case.

If you want to do non-hobby works (commercial, industrial,…) in this field, you need to use current source. the reason of why current sourse is better than voltage source for LED driving, is explained in my previous post.
The CCS (constant current source) is a good keyword in this subject.

thanks ,boldstone ,How can i find the parameters of LED available at market ? Have you a simple design (professionally circuit ) ,only for learning purpose .