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View Full Version : 50 Watt Dichroic vs 3 Watt LED's x 4 or 5 comparison



T.D.Sutton
01-18-2016, 01:51 AM
Question for those more knowledgeable than myself :-)

I am considering replacing the 12 Volt 50 watt Dichroic downlights that I am using, facing upwards, in my "Bubble-wrap" "Mini Trees" with a group of LED's. Currently I have four lamps in each box with colour gels across the front of the Red / Green / and Blue lamps to provide the appropriate colours.

My question is - ?? how many 3 watt LED's will I need to put in in each set to provide a similar light output to the 50 Watt Dichroic's. I have 50 in the post to me at present, in White / Red / Green / Blue, which will negate the need for the colour gels for the three colours :-)

Thoughts ??

Terry

bdecosse
01-19-2016, 05:35 PM
in theory 1:1 approx BUT you used gels so your new red/blue/green might appear better after the change.
It all depends on the factory data for your old and new lamps which gels you used in the past.

Bdecosse

ukewarrior
01-20-2016, 09:38 AM
I agree.
I would think the color LEDs may be brighter.

in theory 1:1 approx BUT you used gels so your new red/blue/green might appear better after the change.
It all depends on the factory data for your old and new lamps which gels you used in the past.

Bdecosse

T.D.Sutton
01-20-2016, 09:43 AM
in theory 1:1 approx BUT you used gels so your new red/blue/green might appear better after the change.
It all depends on the factory data for your old and new lamps which gels you used in the past.

Bdecosse

Hi Bdecosse,

Many thanks for your observations, what you suggest is what I "deduced" by "Google" researching the comparative values for commercially produced down-lights and their Diachroic predecessors. I was aware that there are quite a few "snakeoil" sales pitches going on in the lighting industry, hence my question to those who may have dabbled in home-brew replacements, to find out what they had observed :-)

Cheers,

Terry

Technician
01-20-2016, 03:58 PM
Just for theory, here is how the math pencils out. Start with white. LED to to incan comparison is about 6:1 depending on efficiency. EG 10 Watt LED = 60 Watt Incan. Here is the important difference.

Filter an Incandescent and you kill about 80-90 percent of the power as you only let light of one color through. This varies with color. Red has more output than blue as Incandescent has a warm color temp and blue output is low.

An LED in contrast does not create a rainbow of color and then filter most out to make a color, It is very efficient at making a single color. A 10 watt blue LED for example will be (working backwards) about equivalent to 50 watt in white, or white filtered 90 percent to blue it would be like a 500 watt deep blue filtered PAR fixture.

T.D.Sutton
01-20-2016, 11:03 PM
Just for theory, here is how the math pencils out. Start with white. LED to to incan comparison is about 6:1 depending on efficiency. EG 10 Watt LED = 60 Watt Incan. Here is the important difference.

Filter an Incandescent and you kill about 80-90 percent of the power as you only let light of one color through. This varies with color. Red has more output than blue as Incandescent has a warm color temp and blue output is low.

An LED in contrast does not create a rainbow of color and then filter most out to make a color, It is very efficient at making a single color. A 10 watt blue LED for example will be (working backwards) about equivalent to 50 watt in white, or white filtered 90 percent to blue it would be like a 500 watt deep blue filtered PAR fixture.

Thanks ukewarrior and Technician,

Your observations confirm my reasoning for attempting to head down the LED replacement path. There are two reasons, one the 12 Volt 50 watt Dichroic downlights lamps that are in use currently are typically "yellower/or maybe redder" than bright white by definition, and their 4 + amp current draw through the feeder cables reduces the power/voltage out at the lights considerably. This further "enhances" the colour shift towards Red, and reduces the brilliance as well.

As Technician suggested the colour gels for the Red/Green/Blue is definitely reducing the brilliance further - added to this is the speed that the Dichroic's respond to sequencing switching/control is noticeably lagging behind all the LED's. With all eight Minitree lights on at the same time there is about 35 amps at 12 volts required to light them all up!! If I can replace each of the Dichroic's with a group of LED's this will reduce the current to around 750ma or 1.5 amp per colour per tree, a long way from the 4+ amp per colour per tree at present, and increase the light output for all the colours considerably since no Gel's will be required, and have "instant" response to sequencing commands.

Thanks again for your thoughts :-)

So, ??? should I put 4 x 3 Watt LED's or 5 x 3 Watt LED's when I install them ?? 4 is a lot easier, with all in series, while 5 would require two groups, a 3 and a 2 in series, both set's in parallel, which would push the current up to 1.5 amps per fixture, and have heavier voltage dropping resistors ??

Cheers,

Terry