Questions about purchasing a Robo-Tank DIY Aquarium Controller Kit

[Rob F]

You dont input that robotank 5v pwm signal to ldd input pins :) There is pwm pin for that :)  So that  6-30V  is using to lights.

There is how you hook it up 

Like you see there is designated pin for that pwm signal :) 

As I remember it from wiring up my lights and checking out the specs, the LDD has 5 pins, input voltage, ground, output voltage, ground, and input signal. On that LDD-1500L the max voltage input is 32v, I'm guessing the L is low power because the LDD-1500H can handle up to 56v. Typically when these drivers are used you use the max input you can and run the led's in a series. Then the drivers are smart enough to figure out how much voltage should come out of the driver to power the amount of LED's in the string and puts out a constant 1500ma current. The 0-5v PWM signal coming out of the controller and goes into the LDD driver, the driver is setup to respond to 0-5v PWM. If you input 10v PWM signal to the driver it would be bad I would assume. That's why these drivers are popular among DIY'ers when building a light, they work directly off an Arduino because it puts out 0-5v. So I have to disagree, these will not work. Anyone trying to dim these LDD's using a SmartController would have to drop that 10v PWM to 5v PWM max.

I am just wondering how much current that ic chips last ? Because if each chanels uses 15.5-19.5V DC @ 0.7A. and there is like 8 chanel light, it takes 8 x 0.7A = 5.6A 

and those Meanwell ldd-1500 are kind of "big" and each of them last only 1.5A so i wondering if you tiny ic last those "big" currents, or if it fry :D 

Because it is another thing to just use that pwm signal to "control" some other device which takes the "load" (then current is small about some mA, even voltage is bigger) than using those light directly that signal. And if doing it, your chip/ic must take that load and still running fine (and not get fryed ) :D  

This is where it gets confusing, at least for me. LED's are rated for the different current ranges and voltages required to power them. For example, if you look at specs on different LED's you'll see a pattern for the current, some require 350ma, 700ma, 1000ma and 1500ma. And then there's the voltage to power that single LED, it can be 3v, 5v or whatever, mine are rated for 6.3v I think. There's a formula to figure out the voltage based on current and wattage of LED.

So if you take one of those LDD drivers and input 30v or whatever and connect only a single LED that required 3v it would only put out 3v and the full current would be 1500ma using the LDD-1500L. The number in the model is how much current is outputted. Now if you added another LED in series you would need 6v to power them both so the driver would sense this somehow and put out that much voltage, current remains the same again. You can run the number of LED's on a single driver based on that. If your LED's used 3v and the driver could output 30v then you can run a maximum of 10 LED's on that driver, of course if you are powering the LDD with a full 32v. If a single LED required 6v you could only run 5 LED's on that single driver. 

Another thing, if you had the LDD-1500L driver but your LED's could only handle 700ma @ 6v you can run two strings in parallel. That would mean you would create 2 string in series using 5 LED's and connect them in parallel to driver. With that said its not recommended to do that because if an LED goes out in a string one of them would get 1500ma and would fail as well. If they are in series only and one goes out the voltage is adjusted by the driver and life goes on. :)

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Edit: Cleaned up top explanation.

Also there are two types of drivers, constant current and constant voltage, the LDD's are constant current hence they always put out the current they are rated for and the output voltage changes to match the LED's in the string. The constant voltage are reverse, they put out a constant voltage but the current output varies based on whats connected.

Edit 2: If anyone buy the LDD's for a DIY light its best to get the H version so you can run more LED's on a driver, that's the only difference. I think cost is similar so its a better deal. They pair up good with the 48v meanwell power supply. Amps of power supply depend on total number of LED's.