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> [Sharing] Brand vs cheap LED light bulb, Comparison of LED light circuit design

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ozak
post Feb 8 2016, 11:51 AM

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Brought a ikea e27 led and install it today. It is the last 1 in store. 1000lm with 70l/w, 2700k. Since it is 1000lm, it doesn't look very yellowish.

Not suitable for downlight as the ball diameter is too big for the reflector.

user posted image

This post has been edited by ozak: Feb 8 2016, 11:52 AM
weikee
post Feb 8 2016, 01:57 PM

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My sister's house one chandelier fully led KO just two days ago, and is only just 1+ years

This post has been edited by weikee: Feb 8 2016, 01:57 PM
billyboy
post Feb 8 2016, 06:11 PM

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I just check ikea ledare e14/e27 at rm19.99 each...
ozak
post Feb 8 2016, 11:38 PM

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QUOTE(weikee @ Feb 8 2016, 01:57 PM)
My sister's house one chandelier fully led KO just two days ago,  and is only just 1+ years
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Don't expect too much from China led la.
weikee
post Feb 9 2016, 09:53 AM

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QUOTE(ozak @ Feb 8 2016, 11:38 PM)
Don't expect too much from China led la.
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Yup, still prefer the old technology. LED still not reliable when come to long term usage.
TSikengkai
post Feb 18 2016, 10:41 AM

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QUOTE(weikee @ Feb 9 2016, 09:53 AM)
Yup,  still prefer the old technology.  LED still not reliable when come to long term usage.
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It depend. No doubt the CFL is fairly cheap now, and it last for 2 years +/-. For LED, I had a philips LED 8W warm white as staircase light, it on every night for > 2 years and continue counting. By the way, when shop for LED bulb, remember that price determine the quality. Yes, you can get the best value for money, but does it worth to spend the time & effort for the different of +/- RM5? Go for branded LED bulb with reasonable price. Rule of thumb for myself, RM20 - 35 for LED bulb 7W - 10W. smile.gif
weikee
post Feb 18 2016, 11:35 AM

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QUOTE(ikengkai @ Feb 18 2016, 10:41 AM)
It depend. No doubt the CFL is fairly cheap now, and it last for 2 years +/-. For LED, I had a philips LED 8W warm white as staircase light, it on every night for > 2 years and continue counting. By the way, when shop for LED bulb, remember that price determine the quality. Yes, you can get the best value for money, but does it worth to spend the time & effort for the different of +/- RM5? Go for branded LED bulb with reasonable price. Rule of thumb for myself, RM20 - 35 for LED bulb 7W - 10W. smile.gif
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Yup, i agree price determine the quality. Also you notice many good brand don't have very bright LED (at least in the reasonable price range) that is because bright LED required more quality and good heat dissipation design.

My balcony CFL t5 lasted 4 years before i replace the bulb smile.gif on for 12 hours daily.
Richard
post Feb 19 2016, 12:48 AM

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the technology keeps improving.. and the price should be lower as more and more people move to using LED lighting being higher light output per watt, savings on the brighter light output and reduced heat thus lower air conditioning cost and no poisonous mercury better for our environment,,

still it is better buying branded items as the companies have proper research & development with better reliability.. those using pwm (pulse width modulation) type led drivers would probably last longer than the diode bridge rectifier, capacitor driven designs but in the end it depends on the component's brand quality and reliability ..

you buy cheap, you probably get poor designed high heat exposed low quality crap branded generic electrolyte capacitor type led drivers which dry up within 6 to 12 months..


weikee
post Feb 19 2016, 09:24 AM

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QUOTE(Richard @ Feb 19 2016, 12:48 AM)
the technology keeps improving.. and the price should be lower as more and more people move to using LED lighting being higher light output per watt, savings on the brighter light output and reduced heat thus lower air conditioning cost and no poisonous mercury better for our environment,,

still it is better buying branded items as the companies have proper research & development with better reliability.. those using pwm (pulse width modulation) type led drivers would probably last longer than the diode bridge rectifier, capacitor driven designs but in the end it depends on the component's brand quality and reliability ..

you buy cheap, you probably get poor designed high heat exposed low quality crap branded generic electrolyte capacitor type led drivers which dry up within 6 to 12 months..
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Not only that, cheap driver draw higher current because of poor power factor, this result in heat build up and killing the driver faster.

And also a good read here:

http://www.astrodynetdi.com/power_supplies...ed-drivers/faq/

This post has been edited by weikee: Feb 19 2016, 09:31 AM
TSikengkai
post Feb 19 2016, 09:37 AM

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QUOTE(Richard @ Feb 19 2016, 12:48 AM)
the technology keeps improving.. and the price should be lower as more and more people move to using LED lighting being higher light output per watt, savings on the brighter light output and reduced heat thus lower air conditioning cost and no poisonous mercury better for our environment,,

still it is better buying branded items as the companies have proper research & development with better reliability.. those using pwm (pulse width modulation) type led drivers would probably last longer than the diode bridge rectifier, capacitor driven designs but in the end it depends on the component's brand quality and reliability ..

you buy cheap, you probably get poor designed high heat exposed low quality crap branded generic electrolyte capacitor type led drivers which dry up within 6 to 12 months..
*
PWM? I thought they just use the current regulator circuit to maintain constant current to drive the LED, as current determine the LED brightness. Normal design will be a voltage step-down transformer, follow by current regulator / control circuit. I had heard some of the lighting shop tauke said: when u hold the LED bulb, the heavy will be better... I do not totally agree, but for layman, some sort an easy guidance.
TSikengkai
post Feb 19 2016, 09:39 AM

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QUOTE(weikee @ Feb 19 2016, 09:24 AM)
Not only that, cheap driver draw higher current because of poor power factor, this result in heat build up and killing the driver faster.

And also a good read here:

http://www.astrodynetdi.com/power_supplies...ed-drivers/faq/
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Hi Weikee, look like you are interested and done a lot of reading on LED. smile.gif
Heat will determine life span of LED, the higher heat it expose to and higher operating temperature, the shorter the life span of it.

anyway, nice to meet you.
weikee
post Feb 19 2016, 09:47 AM

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QUOTE(ikengkai @ Feb 19 2016, 09:39 AM)
Hi Weikee, look like you are interested and done a lot of reading on LED. smile.gif
Heat will determine life span of LED, the higher heat it expose to and higher operating temperature, the shorter the life span of it.

anyway, nice to meet you.
*
I used to (10 years ago) play lots of LED bulbs, for electronic project, and also lighting project. And also try out some smt before. That time an LED bulb for lighting usually have a thick layer of clear epoxy coating to protect the LED bulbs, and usually the cheaper LED will have a lousy coating that turned into yellowish / greyish when switch on too long, or expose to heat and this will make the light dimmer and useless.

I build / mod the driver from PC Power supply, that the best and reliable Power supply you can get in the market (10 years ago).
TSikengkai
post Feb 19 2016, 10:24 AM

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QUOTE(weikee @ Feb 19 2016, 09:47 AM)
I used to (10 years ago)  play lots of LED bulbs, for electronic project, and also lighting project. And also try out some smt before. That time an LED bulb for lighting usually have a thick layer of clear epoxy coating to protect the LED bulbs, and usually the cheaper LED will have a lousy coating that turned into yellowish / greyish  when switch on too long, or expose to heat and this will make the light dimmer and useless.

I build / mod the driver from PC Power supply, that the best and reliable Power supply you can get in the market (10 years ago).
*
PC Power supply is once of the cheap & good source for 5V and 12V... lol...
Just need to short 1 wire to ground, then it will output 5V and 12V, I did that to tap the 5V and 12V too.
Richard
post Feb 19 2016, 04:46 PM

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QUOTE(ikengkai @ Feb 19 2016, 09:37 AM)
PWM? I thought they just use the current regulator circuit to maintain constant current to drive the LED, as current determine the LED brightness. Normal design will be a voltage step-down transformer, follow by current regulator / control circuit. I had heard some of the lighting shop tauke said: when u hold the LED bulb, the heavy will be better... I do not totally agree, but for layman, some sort an easy guidance.
*
agree..

so far most led bulbs in market using linear voltage supply(240 ac> rectify dc > stepdown tx > current limit resistor to match led array)..

the newer tear downs on youtube expose variable voltage supply divider with single npn transistor used by philips bulb and some other china manufacturer..

there is another option to use pwm to modulate the voltage using the common 555 timer ic to control npn transistor with an external resistor and capacitor.. i've seen this circuit on a cree xml t6 led..

right now its only on a flashlight but once the china manufacturers start using cloning this technology, their economies of scale will definitely drive the prices down.. pwm is the only logical choice as it improves the power efficiency above 80% as there is no heat wastage across resistors..

i.e voltage modulation via pwm vs linear voltage with current limiting resistor..

the force.. its calling ... to you..
ozak
post Feb 19 2016, 04:56 PM

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QUOTE(Richard @ Feb 19 2016, 04:46 PM)
agree..

so far most led bulbs in market using linear voltage supply(240 ac> rectify dc > stepdown tx > current limit resistor to match led array)..

the newer tear downs on youtube expose variable voltage supply divider with single npn transistor used by philips bulb and some other china manufacturer..

there is another option to use pwm to modulate the voltage using the common 555 timer ic to control npn transistor with an external resistor and capacitor.. i've seen this circuit on a cree xml t6 led..

right now its only on a flashlight but once the china manufacturers start using cloning this technology, their economies of scale will definitely drive the prices down.. pwm is the only logical choice as it improves the power efficiency above 80% as there is no heat wastage across resistors..

i.e voltage modulation via pwm vs linear voltage with current limiting resistor..

the force..  its calling ...  to you..
*
Open up the bulb. measure the led DC supply. Get a laptop adaptor (2nd hand) connect to it. Work for many yrs.
Richard
post Feb 20 2016, 12:30 AM

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I bought this led driver for rm35 a few months ago.. its very very good with no heating issues as opposed to a linear voltage current regulated type led driver..

It accepts a 165-245v ac primary and outputs a dc 57-90v 300mA+-5%

user posted image

Google up hotchip ht2538 will give you this.. Its definitely driven by pwm. The npn mosfet, timer chip are all built in that 8 pin ht2538 chip as shown in the schematic.

user posted image

it can drive an array 2 lines of 30 x 5630's .. not the flexible led strips rolls you buy in the shiny bags..

the ones i use are with aluminium backing with heat paste and really bright.. i could compare the brightness to our Malaysian made Nikkon led street lamps at a fraction of the price.. i've been testing them for a while now,,

This post has been edited by Richard: Feb 20 2016, 12:44 AM

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