TOG's new 240 build with DIY LED's and Controller

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Crit21

Butterfly Fish
#21
#21
I think there are a couple drivers that will allow 5V PWM, but you need to figure out which LEDs you plan to use first. Since LEDs are rated by current, the driver needs to match. 700-750mA seems to be a good goal. Although many Crees are rated up to 1.5A, I'd look for the nominal rating and go with that. The LEDs will run cooler and last longer.

With a constant current driver, you don't need a resistor or fuse in a series-only circuit. The driver adjusts automatically if a short or open occurs.

Parallel circuits are another matter, and I'd advise against them if you aren't intimately familiar with them. Each branch needs a specific resistor based on both resistance and wattage needs. The resistor protects against cascading parallel branch failures if one branch "dies", forcing the remaining current through the other branches, exceeding their rated current, and causing yet another branch to fail. It's a real PITA if you haven't designed the circuit correctly.
 
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that0neguy1126

Registered Users
M.A.S.C Club Member
#22
#22
Yep. Unfortunately, unless I want to run like 12 power supplies. Theres no way to not do it without using parallel.

Here is the PS/Driver. http://www.meanwell.com/search/hlg-185/HLG-185-spec.pdf (24vDC version)
DC Voltage: 24v
Rated Current: 7.8A
Rated Power: 187W
The B model also has the 10v PWM

Using Cree's. I would drive them at 700mA to extend the life, but I do the math at the max, which is 1A(not taking in the 1.5A versions, since I would never drive them that high).

from Cree, when driven at 1A they drop 3.7V. 6 x 3.7V = 22.2V (which gives me 7.5% overhead).
With 7.8A from the Power supply, I could then run 7 strings in parallel. 7 x 1A = 7A (gives me 11% overhead).
With this, all the LED'w would draw 155W (7A x 22.2V=155W). This gives me 18% overhead.

Like you mentioned, each parallel string would have a resistor and fuse on it. Also, since not every LED is perfect on the voltage drop, I would mix and match to keep each string as close to 22.2V as possible.

Also incase anyone is wondering why drive LED's at 700mA and not 1000mA. The lumen drop from that is only 5%, but the heat goes down and therefor life expectancy of the LED's goes way up.
 
Zooid

Zooid

Reef Shark
M.A.S.C Club Member
#23
#23
Check out these drivers. They don't have the PWM dimming but with the Arduino, you could get a 0-10VDC shield to dim them.
http://www.thomasresearchproducts.com/led_drivers.htm#200W Series - Constant Current - 0-10V Dimmable - Long Life

Check out the TRC-200S070DT
Check my math but I think you could use three of these bad boys to do your whole tank. You could use one for the whites, one for blues, and one for the royal blues.
Using this I think you could run each circuit with only one branch so there is no cascading parallel branch problems to worry about.
Just a thought.

I learned of these drivers through Nanotuners. They are going with these instead of the Meanwells because the TRC's can be used without dimming, with a rheostat, or with 0-10 without having to buy a new driver.
Meanwells don't have that flexibility that I can recall.
 
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that0neguy1126

Registered Users
M.A.S.C Club Member
#24
#24
Yea that is one of the other drivers I considered. You can run about 54 3W LED's on each one in series. The problem I have with them is that would be 200vDC flowing through the wires, which is very high voltage. With that you have to start worrying about arcing and voltage creep.
 
C

Crit21

Butterfly Fish
#25
#25
Good idea to drive them at a lower voltage/current. Depending on how closely spaced they are, these LEDs would need a lot of heat dissipation. Excess heat definitely shortens their life.

It's obviously your choice whether to put 42 3W LEDs on a series-parallel (series in each branch, and 7 circuits in parallel) circuit, but I would still advise that you use series circuits. In series, the driver will ensure constant current through each LED, and the manufacturing differences between chips is really no concern regarding voltage drop. As long as they're all the same LED type (XR-E, etc.), they'll be fine. Fuses aren't necessary if the driver has internal protection (most have it). Resistors are not necessary at all. Sure, the downside would be the number of drivers you'd use, but it's not difficult to find a place out of sight on top of or behind the hood for them.

You haven't considered the resistor load on each branch. I'm estimating ~3.5V across each LED, which requires 4.7 ohm resistors. Each 4.7 ohm resistor will burn about 2.6W, and you want at least 60% power overhead for resistors. Resistors rated above 1W can be pricey.

Fuses on each parallel branch will guarantee that you will end up with an open circuit on that branch if a fuse blows. That will mean the remaining 6 branches will carry the extra current. The place for a fuse would be on a common line so it protects the entire circuit.
 
Zooid

Zooid

Reef Shark
M.A.S.C Club Member
#26
#26
I've heard there have been problems associated with running a large amount of Meanwells on a large tank.
Inrush current and harmonics are two of the problems I've heard about. I understand the voltage worries but
if you have metal halides on your tank right now, 200-400 VDC is NOTHING compared to the starting voltage that a M59 ballast puts out. The open circuit voltage of an M59 ballast is close to the voltage of that LED driver, maybe a little less but close.
The voltage is a concern, I've been hit by 250VDC before and it dropped me to my knees, but it's also a concern for every other lighting circuit that we use over our tanks.
 
T

that0neguy1126

Registered Users
M.A.S.C Club Member
#27
#27
Yea. to combat the harmonics, you have to use a power supply with PFC(pretty much any power supply other than the MW ELN have this feature).

There is no getting away with how dangerous electricity is. 250vDC at .7A ... or 24vDC at 6.8A... Both are deadly. The problem with DC vs AC, is DC will lock you up and keep you in line of the power, where AC will kick you back and break the connection.

I should take a closer look at what it would take to safely insulate the wires and the heatsinks from the 250vDC as it would be cheaper and easier. I don't have any experiance working that high in voltage. 48vDC is the highest I've had to work on.
 
Zooid

Zooid

Reef Shark
M.A.S.C Club Member
#28
#28
that0neguy1126;75131 said:
The problem with DC vs AC, is DC will lock you up and keep you in line of the power, where AC will kick you back and break the connection.
Click to expand...
I've had the exact opposite experience. It's true that DC with cause your muscles to contract so if you are grabbing something and get bit, the DC will cause you to grab on and hold on. I've never been kicked back with AC. normally it held me longer than DC because I wasn't grabbing anything when I got hit with 250VDC. After it knocked me to my knees, it felt like my hand had just been smashed with a sledgehammer. :D
AC (120V) normally just pi$$e$ me off. Anything greater than 120VAC hurts almost as bad as DC. But your right, both are dangerous. Hell, 12VDC car voltage can be enough to kill you because it isn't the voltage that kills, it's the current that passes through you that kills you. Lower voltages are just a little safer because normally your body resistance is high enough to keep the current low.
 
Zooid

Zooid

Reef Shark
M.A.S.C Club Member
#30
#30
No, that's the problem. They are new to the scene as far as I know. I know that Nanotuners is going to go exclusively with them.
Nanotuners is using a smaller lower voltage unit and they are selling 120W units but don't know if anyone has tried the bigger units.
 
dv3

dv3

Beluga
M.A.S.C Club Member
#33
#33
TOG you should pm stugray and thegrimreefer to get them to comment here as well ...you already have alot of great opinions and already over my head ...lol...but i know these have built some nice ones and know there stuff as well
 
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that0neguy1126

Registered Users
M.A.S.C Club Member
#34
#34
It depends on what colors and manufacturer I want. But somewhere from China. As soon as you buy from the states the price per led doubles.

I did pm stu, but no response yet.

Sent from my HTC Incredible
 
Zooid

Zooid

Reef Shark
M.A.S.C Club Member
#36
#36
Yikes, didn't realize you had to solder all the parts on yourself hehe.....do you have a link on the hydra controller?
 
T

that0neguy1126

Registered Users
M.A.S.C Club Member
#37
#37
http://www.reefcentral.com/forums/showthread.php?t=1783536&page=50
Here is the original thread. Lots of developmental stuff in there that is way over my head.

You can also go to http://www.hydra-reef.com or http://code.google.com/p/hydra-reef/wiki/Intro?tm=6

I got 2 main boards from someone off RC (most PCB fabricators require you to buy 10 at a time). So I may have a spare PCB as long as I don't break the other. I have also be thinking about building 2 and selling the other one for cost to someone who wants it.

Yep. Its only about 50-60 components. It's been a few years since I have had to solder, but shouldn't be too big of a problem. It's like riding a bike right?
 
Zooid

Zooid

Reef Shark
M.A.S.C Club Member
#39
#39
I think we need a reflow station. Then we can use surface mount components and can even buy the ribbons of LED's and solder them onto a star with the station :D
 
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