I just got all my parts in and I am going to start "tinkering" today. I will keep everybody posted. I wanted to put everything down and have everybody comment on it, especially BEFORE I power it all up.
I ordered 8 CREE MC-E stars. Each star/MC-E is setup for parallel, not series.
I have a 4 foot long piece of heatsink. My goal is to test an alternative to flourescent lighting for my workbench in my garage. Hence the reason I chose it to be 4' long and need to use multiple MC-E's.
I found a constant current power supply, the ELP60-27 made by Astrodyne. It is made for driving LED's. It puts out 2.3A constant, voltage of 15-27VDC and at 60Watts total.
I am going to mount the 8 MC-E stars on the 4' heatsink, evenly spaced, so they are about 5.3" from each other. I think that with a 4" wide by 4' long heatsink only holding 8 MC-E's at 5" from each other, there should not be a problem with overheating or keeping them cool. Anybody have any comments on that?
Last, I know that series is always best for consistency but that would require a power supply that has high voltage and .700mA constant current. I had a hard time finding this. So I am going with a series-parallel design. I am assuming that binning is easy with the MC-E with respect to the four LED's on the one die. You have to figure that it couldn't be binned any closer because they were put together at the same time on the same die. Therefore, I think it would be best to parallel the 4 LED's on the die and then run in series to the other LED's on the other dies.
This puts me at 4 parallel strings (due to the 4 LED's on the die) in series to the other MC-E's which will then be in paralled internally again. This puts me at 8 MC-E's total.
Here is where I need re-assurance and confidence before I power it all up. My math says that I will have 2.3A total, divided by my four parallel strings so each will get 575mA (2.3A / 4).
As for my voltage (which I know fluctuates slightly due to temperature) I have 2.5Vf per LED. In the series-parallel arrangement, this should put me total voltage drop around 20VDC (2.5Vf * 32 LED's = 80VDC / 4 parallel strings = 20VDC) which is well within my 15-27VDC range of my power supply.
Last, if each LED is around 2.5Vf and I give it 575mA, that should put me around 1.5Watts per LED (1.4375 to be exact but I like to round up). This 1.5Watts per LED multiplied by the 32 total LED's puts the total wattage at 48 which is under my 60Watts maximum allowed by the supply.
According to my math, this should all work out. Please, please let me know your comments. Especially if I am doing something wrong, missing something or if I can do it better. Otherwise, I will gladly share my results along the way.
Thanks!!
Mike
I ordered 8 CREE MC-E stars. Each star/MC-E is setup for parallel, not series.
I have a 4 foot long piece of heatsink. My goal is to test an alternative to flourescent lighting for my workbench in my garage. Hence the reason I chose it to be 4' long and need to use multiple MC-E's.
I found a constant current power supply, the ELP60-27 made by Astrodyne. It is made for driving LED's. It puts out 2.3A constant, voltage of 15-27VDC and at 60Watts total.
I am going to mount the 8 MC-E stars on the 4' heatsink, evenly spaced, so they are about 5.3" from each other. I think that with a 4" wide by 4' long heatsink only holding 8 MC-E's at 5" from each other, there should not be a problem with overheating or keeping them cool. Anybody have any comments on that?
Last, I know that series is always best for consistency but that would require a power supply that has high voltage and .700mA constant current. I had a hard time finding this. So I am going with a series-parallel design. I am assuming that binning is easy with the MC-E with respect to the four LED's on the one die. You have to figure that it couldn't be binned any closer because they were put together at the same time on the same die. Therefore, I think it would be best to parallel the 4 LED's on the die and then run in series to the other LED's on the other dies.
This puts me at 4 parallel strings (due to the 4 LED's on the die) in series to the other MC-E's which will then be in paralled internally again. This puts me at 8 MC-E's total.
Here is where I need re-assurance and confidence before I power it all up. My math says that I will have 2.3A total, divided by my four parallel strings so each will get 575mA (2.3A / 4).
As for my voltage (which I know fluctuates slightly due to temperature) I have 2.5Vf per LED. In the series-parallel arrangement, this should put me total voltage drop around 20VDC (2.5Vf * 32 LED's = 80VDC / 4 parallel strings = 20VDC) which is well within my 15-27VDC range of my power supply.
Last, if each LED is around 2.5Vf and I give it 575mA, that should put me around 1.5Watts per LED (1.4375 to be exact but I like to round up). This 1.5Watts per LED multiplied by the 32 total LED's puts the total wattage at 48 which is under my 60Watts maximum allowed by the supply.
According to my math, this should all work out. Please, please let me know your comments. Especially if I am doing something wrong, missing something or if I can do it better. Otherwise, I will gladly share my results along the way.
Thanks!!
Mike
