indoor lighting test with LEDS(pics) + need info on dimmers?

JinMTVT

Member
2004-07-12 2:30 am
MTL
I have ordered a few expensive pieces of LEDS
from Seoul Semiconductor
http://www.acriche.com/en/
wich are AC 120V driven direclty
( there are a 2 resistors on the pcb though )
I believe that they use the up and down of the AC
to drive and reverse/drive 2 different 1W section of the LED pannel, something like that ..quite simple
and that removes the complexity associated with LED electronics and voltage requriements ...

So that said , i now have 10 6500K
( was the only one avaiable by then) 4W ( 2 2W leds on each pcb ) "specialist" Acriche LED units @ 21$USD each from www.avnet.com
I will be receiving some 3000K version of the same leds this week for further analysis.

My point was to test the usability of leds for indoor lighting to replace annoying CFL bulbs and plain ridiculous incandescent light bulbs.

So i tried to compare them to what was available at the moment in my house to see how they could be used.

Here are a few samples of the tests i did for the interested of you.

1- 6X4W LEDS 6500K ( total 24W )dispersed on the ceiling VS 1 phillips daylight 27W CFL ( quality one @ 5500K)

Please do not mind the color temperature difference, i tried to attenuate it by using automatic white on my camera ....the camera was setup to give the best exposure that represented the actual scene as seen with my eyes.


27W CFL
http://img526.imageshack.us/img526/5530/dsc05398ho4.jpg

24WLED "star" setup
http://img526.imageshack.us/img526/6910/dsc05399eb8.jpg
 

JinMTVT

Member
2004-07-12 2:30 am
MTL
following test was done at kitchen
2 led modules for 8W total were used VS
2 50degree halogen 50W spots
( please keep in mind here that the leds are 110degree patern, so there is no bright spot as seen with the 50degree spots ... thought i do not see it would be a problem if the leds were recessed in a cone spot enclosure ..to be tested )

2 50W halogen spots 50deg.
http://img526.imageshack.us/img526/1473/dsc05403lk0.jpg

2 4W acriche led modules
http://img182.imageshack.us/img182/6635/dsc05405db6.jpg




Now this test is again 2 4W acriche led module VS 3 30-40W candella type incandescent in a round mount under a diffusing white glass ornment

i'd say that the total light output was a little higher with the 2 leds than with the incans here ..

incandescent lighting
http://img526.imageshack.us/img526/5530/dsc05408br7.jpg


2 4W LEDs
http://img526.imageshack.us/img526/2987/dsc05409kq9.jpg


Again do not take care of the color temperature..
only brightness and illumination is in test here



I like what i've tested, and i will be investigating those new LEDs again much soon,
as i intend to use them in 80%+ of my future house lighting !!

What do you think ?

have you personally done tests with leds?

i know there are many more efficient modules,
but none has the retrofit possiblity and the easiness of those 120V AC units ..
 

JinMTVT

Member
2004-07-12 2:30 am
MTL
Now onto the dimming subject ..


how do regular dimming control works ?

what do we want to control those leds?

i've read that LEDS are current driven units,
but they regulate their current depending on the feeded voltage ..do not know if those are of the same...

I'd very like to be ablet o test those leds with some dimmer, i'll try to purchase one this week end at the store to see how it works wiht the leds.

i've also read that some dimmers work by switching on/off at different speed so there is no power loss from dimming .

my ultimate goal is beeing able to use those leds with regular Z-Wave dimmers to setup automation correctly

neway, any info on dimmers for lighting will be appreciated! :)
 
LEDs are usually powered by DC. Dimming is done by PWM of the DC power source. Without knowing more about those LEDs, it is hard to say what to use for dimming.

It looks like the LEDs aren't nearly as bright as your other test lamps. You may need more than the one's you tested with. If you calculate the cost of light bulbs and the electricity to run them and compare it to the LEDs, I think you'll find the break even point of LED vs incandescent is on the order of 200 years or so. LEDs are just too expensive right now to make economical replacement of incandescent or CFL. Of course, there's something to be said for being the first guy on your street to light his house with LEDs.

I_F
 

JinMTVT

Member
2004-07-12 2:30 am
MTL
I do not have any interest in showing off my stuff...
so beeing the first guy in the hole province to use LEDS as main lighting doessn't matter much to me.

We pay around 4$ for thos 50W halogen spots..
wich are usually on from 5pm to 11pm on most days
We've been here for 6 years now,
and i can remember to having changed them at least 2-3 times each ..

that + the fact that it is 100W VS 8W
even if i'd throw in another LED for the spots, would probably be a bit brighter than the halogens...still be only 12W ..

now i know that there isn't much economy here,
+ the elctricity is damn cheap here in Quebec ...
but the form factor ( even with a cheap lasercut+stamped aluminum basket for heatsink/mounting... ) wich is pretty small if you ask me,
and the fact of not having to change a single bulb ever...

then, they are sellling for 20$ now ..probably around 12-13$ by the next 6 months..maybe 10$ in 1 years

The kitchen test is kinda fouled because the angle of the light is not comparable at all ..
i'f i'd be to use a collimating lens to something like 50-70degree just like the 50deg for the spots,
you'd see another picture here

the leds were lighting up stuff way further than the spots here, but the light on the countertop itself was alot less bright ...

the for the bathroom test VS incan...
well the leds were actually lighting up more than the regular bulbs, and the light was more equally distributed.... to be seen with 3K ones, since they are supposed to be alot dimmer.

then government is trying to pass a law here,
so that no incandescent are allowed within 2 years

I will not design my house lighting for a 2 year spawn,
and unfortunatly, CFL doesn't have anything other than efficiency that i want as lighting.

I'll try to dim the leds with TRIAC dimmer this week if i can find any..to see how it reacts to it!
 
I have been curious about these myself.
"wich are AC 120V driven direclty
( there are a 2 resistors on the pcb though )
I believe that they use the up and down of the AC
to drive and reverse/drive 2 different 1W section of the LED pannel, something like that ..quite simple"

if this is indeed true (which is how it has seemed to me at first glance) AND these are good light quality, design, built, etc... then this is an elegant solution. Simple is good.

The problem I can see you may have with dimmers is that you may begin to visibly see the chopping. LED's have fast response, and any breaks in the power may become visible. -- As you point out, these work by having one light always on each half of the cycle. Persistence of vision will get part of the way, but the dimmer may break this down further. I may be wrong. They may switch fast enough... (or there may be other tricks at work in these "bulbs") similar to new 120Hz LCD TV's and issues around such...

For proper brightness control you might need a more linear control of the voltage or current. Current limit with increased resistance for a given voltage, or lower the voltage. So likely you could use a variac (or fast PWM), or a big potentiometer. (for the latter, you may need to experiment, or determine the R's in the lights now and calculate a bit) -- edit note: that is big, as in W not necessarily big R for the pot ;-)

?? can't wait to hear some of your results ;-)
 

JinMTVT

Member
2004-07-12 2:30 am
MTL
the current dimmers seems to work with the Triac method, and it seems to operate @ 120hz

i do not believe there is any problem with the switching on/off action used on a LED
would have to contact SeoulSemi for that one i guess

there is no point if the leds fail after only a part of their minimum lifetime

there is a description on one site,
that said that those leds work as if there was alot od diodes onto each other until it made for 120V
and then there is another batch for the reverse AC wave
not too sure if i understand it

The light output from the 6500K pure white version is good..but the color temp is really bad
and the CRI is only of 70

the 3000K i have ordered, have a 92CRI
wich is just about the best u can get from most quality light sources ...

i also thought about the led rise and fall time,
i'll have to test it out i guess!



I have to understand how the latests Z-wave dimmer works, so i can see if it is the same or not,
and if we can use those for the leds...not much information on the net about the internals of such products though !
 
PWM dimming of LED's may cause video rainbows if the rate is to slow. I know that some expensive cars on their tail-light / brake-light combinations. On a dark curving road they video rainbow, well it's more like a strobe.
Video rainbow is a term used when a projection TV (front or rear) with a color wheel has a momentary rainbow like flash.
 
In making calculations of economics beware of the supposed 50,000 hour lifetime claimed for LEDs. They still claim 5-7 year life for CFLs but I have never had one last more than 2 years.

Those lifetime specs for CFLs and LEDs are based on very critical application specs- they must be on continuously, temperature must be in a specific narrow range, etc., all unrealistic of real-world use. The botom line is the marketing guys lie about these things in order to sell more of them.

I_F
 

konaneil

Member
2008-01-22 10:26 pm
>>I wonder whether some good motion sensors well located to turn off lights when no one is there and turn on automatically when people move would be a better energy saver.<<

I live on an island where electricity is quite expensive. Came up with the same solution. The trouble is that at least with the motion sensors they sell at Home Depot, they wear out about as fast as modern light bulbs. Sometimes go on by themselves too.
 

soongsc

Member
2005-03-26 2:31 pm
Taiwan
konaneil said:
>>I wonder whether some good motion sensors well located to turn off lights when no one is there and turn on automatically when people move would be a better energy saver.<<

I live on an island where electricity is quite expensive. Came up with the same solution. The trouble is that at least with the motion sensors they sell at Home Depot, they wear out about as fast as modern light bulbs. Sometimes go on by themselves too.
The problem I had was them going off while I was still in the room. Some are so insensitive that you have to almost dance in front of them to get their attention. Saw some good and sensitive ones a month or so ago made in Germany.
 

konaneil

Member
2008-01-22 10:26 pm
soongsc said:

The problem I had was them going off while I was still in the room. Some are so insensitive that you have to almost dance in front of them to get their attention. Saw some good and sensitive ones a month or so ago made in Germany.


Forgot about that. My wife would make the same complaint when we had one in the bedroom closet. She got mad when I asked if I could watch:D

Soongsc; Do you have a link for the high quality German ones? Do you know if they have 110 Volt? On your island you would need this as well.

One good thing: While I'm sure your energy costs are high like ours in Hawaii, at least with the climates we both have, we don't have the huge winter heating bills much of the world has.
 
I_Forgot said:
In making calculations of economics beware of the supposed 50,000 hour lifetime claimed for LEDs. They still claim 5-7 year life for CFLs but I have never had one last more than 2 years.

The other thing which lighting architects figured out (peculiar that it took them a while) LED's don't like heat -- even their own -- they are semiconductor devices after all -- so unless you push air you can't bunch them together.

Agilent and Phillips have a lot of great white papers on LED's in various industrial applications.
 

JinMTVT

Member
2004-07-12 2:30 am
MTL
I_Forgot said:
In making calculations of economics beware of the supposed 50,000 hour lifetime claimed for LEDs. They still claim 5-7 year life for CFLs but I have never had one last more than 2 years.

Those lifetime specs for CFLs and LEDs are based on very critical application specs- they must be on continuously, temperature must be in a specific narrow range, etc., all unrealistic of real-world use. The botom line is the marketing guys lie about these things in order to sell more of them.

I_F


I will keep that in mind. thanks :)

The fact that CFL and incandescent are really POS lighting solutions, pushes me more and more toward the LED as a solution ...
but i will need alot more testing to be convinced
( i still have a few months before i need to setup lighting in the house .. )



jackinnj said:


The other thing which lighting architects figured out (peculiar that it took them a while) LED's don't like heat -- even their own -- they are semiconductor devices after all -- so unless you push air you can't bunch them together.

Agilent and Phillips have a lot of great white papers on LED's in various industrial applications.

Can you link those papers? should be very interesting ..


I have just received the 3000K acriche LEDS
and will start testing with them tonight.
The CRI index is of 90-92 compare to 70 for the 6500K

I'd also like to be able to have them no "flash" when dimming .. but i'm sure we will come up with a good solution by the time i need to implement them!

The thing about packing them together,
is that it is unnecessary for regular interior lighting
have you ever seen a 1000W spot in a house?
or even inside a building ( other than a theater projector... )

The size of those things makes them suitable for mouting almost anywhere..
and someone that would have a opend joist ceiling
( my house will have 0 recessed space between the ceiling and the foam under the flooor of the top room :(
)

can use a passive radiator heatsink in this space,
making the appearance of the led itself very small
in the actual room ( gives more design options..
like a "star" ceiling with individual leds where u do not even see anything other than a 1cm diameter hole in aluminum in wich the led is mounted )

still haven't got a hold of a regular dimmer

will take time to study those led's specs/tech papers
to see if we'd have to dim from voltage or current to get the best results ...

will keep you guys updateD :)
 

JinMTVT

Member
2004-07-12 2:30 am
MTL
I did a bit of testing with the new 3000K Acriche
LEDS that have arrived today.

I have to admit that i am severly deceived.
I was waiting for a CRI90+ warm white 3000K
nice and mellow/yello colored light ...

For starters, as with all LEDs, the warmer the color temp,
the less output the LEDs produce.
this resulted in estimated 30-40% less light output than the 6500K ones ( usable light without additional lens here )


here is the 4 4W leds VS incan for color comparison

here u can see the blue/green tints of the supposed 3000K led
http://img171.imageshack.us/my.php?image=dsc05416xh5.jpg


comparison shots of the 16W 4 units 3K K Acriche
VS ~ 100W incandescent

http://img171.imageshack.us/my.php?image=dsc05417xf6.jpg

http://img99.imageshack.us/my.php?image=dsc05418js2.jpg



The onto the halogen test ...again 4 4W vs 2 50W 50deg spots

http://img244.imageshack.us/my.php?image=dsc05419vs2.jpg


http://img171.imageshack.us/my.php?image=dsc05420hs0.jpg




Here is a quick setup of under cabinetry lights using those same 4 4W acriche

i believe that it is where they perform the best
though a bit too bright ( i'd prefer half bright at twice the location ...or a bright led rope )

the pictures may be blurred cause i am using slow speeds with handheld shots ...but the last one shows pretty much what the color and light output looks like in real...it is pretty much white white
but surely not warm white at all ..

http://img99.imageshack.us/my.php?image=dsc05426cs5.jpg

i'm tired now ..

let me know what you think ..
but i am going to sleep with much deception
 

JinMTVT

Member
2004-07-12 2:30 am
MTL
there is something i do not understand..

i just tried the 4 4W acriche in my bedroom,
no other lights ( other than the light that gets out of my computer LCD ...42" :p )

and there is a big difference in color betwen the 6500K and the 3000k ...much more than all my pictures show

an the lightoutput is very pleasing ...a lot more than it was earlier today when setup in my tests


I have contacted GE to get sample/units of their new super white leds VIO thing ...
supposed to be dead on color with 100 K of variance at maximum over 50 000 hours ..
and 50K hours at 70%+ light output under normal use circumstances ( again maybe a twist here .. )
 
Hi,
how do they reduce the voltage from 110/120Vac to the 4V or 5V that the LED needs?

How much power does the LED dissipate?
How much power does the control/dropping circuit dissipate?

If you want high lumens/W from your LED lighting then using a series string fed from a low voltage supply that minimises the losses is more likely to save electricity.