Luminus CMX-22 Generation 3 in Europe?
- Thread starter BurgerBro
- Start date
BurgerBro
Member
Actually, there is one other thing that bothers me. Let's say that I would run 8 CXM-22s in series on a HLG-320H-C700, using the Ideal 50-2204-CT Holders. Then I would be running approximately 400v over those Ideal holders that are only rated for 250v! Is that safe, especially in a damp environment?
From looking around the net it seems that similar setups aren't too uncommon.
From looking around the net it seems that similar setups aren't too uncommon.
BurgerBro
Member
I assume you mean HLG-320H-48A? (without the 'c')
In that case I have few questions. I have basic electronics knowledge, I just haven't ever worked with COBs, so please excuse their basic nature:
Is 48v enough to turn the COBs on at these low currents? The CMX-22 datasheet says 50-55v.
Do I simply parallel wire the COBs and rely on the resistors in the driver, or do I need separate resistors for each COB?
I would probably want the B version driver so I could play with PWM dimming via Arduino or Raspberry Pi, would that make a difference?
If I want to drive the COBs softer or harder, can I simply add more or less COBs to the same driver? So on a, say, HLG-240H-48 4 COBs would run at 60W each, and 6 COBs would be 40W each?
I hope you don't mind these kinds of questions. Also, should I email you before I order?
In that case I have few questions. I have basic electronics knowledge, I just haven't ever worked with COBs, so please excuse their basic nature:
Is 48v enough to turn the COBs on at these low currents? The CMX-22 datasheet says 50-55v.
Do I simply parallel wire the COBs and rely on the resistors in the driver, or do I need separate resistors for each COB?
I would probably want the B version driver so I could play with PWM dimming via Arduino or Raspberry Pi, would that make a difference?
If I want to drive the COBs softer or harder, can I simply add more or less COBs to the same driver? So on a, say, HLG-240H-48 4 COBs would run at 60W each, and 6 COBs would be 40W each?
I hope you don't mind these kinds of questions. Also, should I email you before I order?
CobKits
Well-Known Member
yup, corrected
thats "typical" voltage based on their "typical" operation (not necessarily yours). the datasheet also has a Voltage vs current curve. heres a curve from the simulator on their site. thats for a single temperature, but in general on a given size heatsink it will be cooler at low currents (actual voltage will be lower than seen here) and hotter for high currents (voltage will be higher than seen here)
you dont need resistors at all. driver is incapable of going over about 53.5V which is gonna limit your cobs to about 80W each even if you only hook up one
if you want B dimming you want the -54B driver. the B series has a hard cap at stated voltage (54V in this case) as voltage is not adjustable upwards like the A series. You'll lose about 10% current capacity over the 48A unit
yes thats the beauty of parallel wiring with low voltage drivers. since we all like to tweak constantly, it future proofs your drivers eseentially (well it marries you into ~50V cobs but there are plenty of offerings there. there seem to be more 50V and less 36V offerings year over year.)
CobKits
Well-Known Member
not unless you have questions. ordering process is pretty straightforward emails arent needed unless theres somehting you need to convey to me, like special shipping instructions, declared value, etc. i will say it often takes an extra day to get international orders out because of the customs paperwork
BurgerBro
Member
Thanks, man! Very helpful!
I am not complaining, mind you. This is a very nifty safety feature.
I honestly don't understand why so many people run the constant current drivers anymore. This way is clearly safer and better in almost every way, and from the datasheets it looks like the constant voltage driver are more efficient as well, especially dimmed. Thanks for showing me the better way!
This is where we reach the limit of my understanding. The way I have learned to deal with diodes is to assume they are "perfect diodes", meaning that they have infinite resistance until their forward voltage is reached and their resistance drops to zero. Such diodes don't exist in reality of course, but the assumption works in most cases. The COB being limited to 80W at 53.5v would indicate that the COB has a resistance of almost 35.8 ohms in its 'open' state, which is really quite significant. What is going on with that? Do the COBs have built-in resistors, or is the high resistance simply a consequence of having about 130 less than perfect diodes stringed together?
I am not complaining, mind you. This is a very nifty safety feature.
Yeah, that really is a great way of doing it. Another way to look at it is that you can get the same amount of the same type of COBS next year when something better comes out. That way you will be running them even more efficiently, so more light for the same money and with better spread. And you may even be able to get them at a discount, since they will be last years model by then...
I honestly don't understand why so many people run the constant current drivers anymore. This way is clearly safer and better in almost every way, and from the datasheets it looks like the constant voltage driver are more efficient as well, especially dimmed. Thanks for showing me the better way!
CobKits
Well-Known Member
well resistance couldnt drop to zero or there would be no "work" veing done to create light
yup
CC is more foolproof i guess, but with proper driver selection theres little risk. the 48As just fit the "50V" cobs very very well on voltage