Reef Pi Compatible Lighting

[oreo54]

AFAICT the series resistor is to limit the current draw on the 5V pin..

Pull down resistor is from PWM output to ground.. IF I remember correctly..
Used to keep the lights off in the event of controller failure.
without it lights go "high"....

Better diodes, usually larger heat sinks though cheap fans sort of negate that, and yes, control is what really boosts thier price.
We could argue over and above what is err" correct pricing" but that's Capitalism for you..
what the market will bear..

 

[Ranjib]

reef lights are purpose made light. You are looking at 440-460nm range lights (mostly blue) with most other colors removed (to limit algae growth and other unwanted stuff). Folks tend to mix UV, royal/cool blue. There are ample DIY information using cree, phlips and other off the shelp LEDs. You are aiming for 5watts per gallon light (roughly) and run it at 80% (to get atleast 3Watts per gallon). You will not be able to get the spectrum or the intensity using common LEDs. They'll consume decent current, cooling is a key aspect of such lights.

 

[pseudorand]

AFAICT the series resistor is to limit the current draw on the 5V pin..

Pull down resistor is from PWM output to ground.. IF I remember correctly..
Used to keep the lights off in the event of controller failure.
without it lights go "high"....

Better diodes, usually larger heat sinks though cheap fans sort of negate that, and yes, control is what really boosts thier price.
We could argue over and above what is err" correct pricing" but that's Capitalism for you..
what the market will bear..

I'm not sure how those are different. I don't have circuit diagram software handy, but I have

rpi phy24/GPIO18 -> MOSFET Gate pin -> 10k Resistor -> rpi ground pin.

So I think my resistor is the pull-down. The circuit works fine sans any other resistors.

 

[pseudorand]

reef lights are purpose made light. You are looking at 440-460nm range lights (mostly blue) with most other colors removed (to limit algae growth and other unwanted stuff). Folks tend to mix UV, royal/cool blue. There are ample DIY information using cree, phlips and other off the shelp LEDs. You are aiming for 5watts per gallon light (roughly) and run it at 80% (to get atleast 3Watts per gallon). You will not be able to get the spectrum or the intensity using common LEDs. They'll consume decent current, cooling is a key aspect of such lights.

Why just blue? Marineland sells these with the desired blue, but they also include red @ 630nm. Corals don't need/want red? They seem to be unable to unwilling to disclose the PAR in the Q&A though.

Cooling makes sense for the compact lights like the Kessil A80, but if I have the same amount of light spread out over a large area cooling may be unnecessary, no? Kessil likewise doesn't seem to list a PAR rating, but they do say it draws 15W.

To be clear, I'm not trying to save money via DYI. That's likely a lost cause given what I've already spent on various fits and starts. I simply want a single interface for my entire tank. Lights. Temp. Salinity. pH. Flow. Auto-feeder. Camera. Remote control sub. Web UI. PWA for my phone. I know reef-pi doesn't do all of that at present, but that's a simple matter fork and contribute. Proprietary controls from the reef light vendors don't let me do that.

 

[oreo54]

I'm not sure how those are different. I don't have circuit diagram software handy, but I have

rpi phy24/GPIO18 -> MOSFET Gate pin -> 10k Resistor -> rpi ground pin.

So I think my resistor is the pull-down. The circuit works fine sans any other resistors.

Take the pi off line and see if lights go on full
If the meanwell PWM pin floats (or not using it) lights go to full on

R1 Is the current limiting resistor. Meanwells don't pull much current on the dim circuit but some people add this one.

R2 is the pull down to make sure lights go "off" in a controller failure.


A series resistor in the pi to meanwell PWM is purely for protection of the pi pin.
A 10k resistor from Meanwell dim wire to ground is a pull down to protect the tank in the event of controller failure.

At least that is how I understand it..

most LDD boards have the pull down built in..
Some like RapidLED are jumpered so it can be taken out of the circuit.
Good for testing things..

 

[NeonRabbit221B]

Not meaning to rob a thread but I have a question and want to make sure I am on the right track.

Running a fluval evo stock light that I would like to control from my pi to do the ramping. Based on my dosing requirements I find that I really only need to dose Alk and was hoping to add 1 dosing pump to my current build. From what I understand I think I can use one of the Pi's PWN to a mosfet to control the 13.5 V light and the other PWM to signal to the L293D. In this case I wouldn't need a PCA9685 unless I want to upgrade my lights or add additional dosing later on correct?

 

[pseudorand]

Can anyone confirm or deny that I can connect 4 x Meanwell LDD-1000H drivers to a single Meanwell NES-200-48 power supply and independently control 4 strings of LEDs that way?

Facts:

• The PSU has a single channel output rated at 211.2W (= 48V * 4.4A).
• The drivers have a max output of ~54W (=1A * 52V / 97% efficiency) .
• 54W * 4 circuits = 216W. (Perhaps I can only connect 3 instead of 4)

Questions:

• Is that the right calculation, or is there something I'm missing
• The drivers let me dim each circuit independently even though they share a PSU, correct?
• The drivers have a dimming pin (diagram) that I'll connect to my reef-pi. This takes the place of the MOSFET in all the circuits described above, correct?

At the moment I'm neck deep in DIY LED. I eventually hope to post my learnings on a build thread to help others, including an analysis of if DIY has any benefits (financial or otherwise) other than learning, but I'll be honest and give it a 50/50 that I get around to that.

 

[Michael Lane]

I think your calculations are generally correct, except that you will be running the drivers at 48v instead of 52v. That power supply may be fine if you are not running the maximum number of LEDs on each channel and aren't at 100% output. I would personally look for a different power supply since I prefer to keep the load < 80% of the rating.

The drivers will let you dim each circuit independently. In addition to connecting the DIM pin to reef-pi, you'll also need to have a shared GND between reef-pi and the Meanwell drivers.

 

[pseudorand]

Does anyone know what makes the expensive reef lights better? If it's just spectrum and intensity:

• Spectrum: Won't any 3-channel/RGB LED let me set the spectrum to whatever I like?
• Intensity: Won't lots of smaller LEDs (such as strip lighting) provide the same intensity as one big one, while also alleviating spotlight effects?

Is there something besides spectrum and intensity that makes the expensive reef lights different? (Don't say control, reef-pi will give me that.)

To answer my own question, bulk reef supply says it all.

TL;DW: Just buy a Kessil, or use the Lumina stuff for DIY.

Summary / Why:
* Kessil has supposedly research-based coral-specific spectrum mix (if you believe that). You can duplicate that with DIY, but good luck with that.
* Kessil's optic mixes the colors, giving you that "shimmer". It's unclear if this is important for coral growth, but it prevents stripes of different colored light, which look funny. The Lumina DIY stuff has an optic and might do something similar.

So lots of little LEDs will have worse per-color spotlight effects. And LEDs are single color, so rather than RGB, you'd need 3+ channels for various colors.

 

[oreo54]

Can anyone confirm or deny that I can connect 4 x Meanwell LDD-1000H drivers to a single Meanwell NES-200-48 power supply and independently control 4 strings of LEDs that way?

Facts:

• The PSU has a single channel output rated at 211.2W (= 48V * 4.4A).
• The drivers have a max output of ~54W (=1A * 52V / 97% efficiency) .
• 54W * 4 circuits = 216W. (Perhaps I can only connect 3 instead of 4)

Technically w/ a 48V power supply driver voltage will max around 45V (driver overhead)
What the string voltage is is based on V(f) at that drive current..

If you have diodes with a V(f) of 3.6V @ 700mA then your driver is capable of running
45/3.6V =12.5 diodes or really 12..
12 x 3.6 x .7 = 30.25W or 2.54W each.

BOTH current and what the diode voltage is AT THAT CURRENT is important.

Questions:

• Is that the right calculation, or is there something I'm missing
• The drivers let me dim each circuit independently even though they share a PSU, correct?
• The drivers have a dimming pin (diagram) that I'll connect to my reef-pi. This takes the place of the MOSFET in all the circuits described above, correct?

Yes ps is independent of dimming..
and yes driver is where the mosfet is but it's more "complicated" than a simple high speed switch.

 

[k2-]

Coming late to the party here but , I have connected kessil H80 to the Robo-tank (using reef pi) , however i am not able to control the color modes. Is it possible ? if yes how do i get the proper color controls (RGB etc) ?

 

[oreo54]

Coming late to the party here but , I have connected kessil H80 to the Robo-tank (using reef pi) , however i am not able to control the color modes. Is it possible ? if yes how do i get the proper color controls (RGB etc) ?

AFAICT you only have 2 channels.. "Blue" and Red..

There are no white LEDs in the Kessil H80, just blues and red in the right proportion to stimulate the chlorophyll of plants,

 

[Ranjib]

AFAICT you only have 2 channels.. "Blue" and Red..

Yes. I dont use H80. A80,A160,A360 all uses two pwm inputs, one for intensity and another for color (cool white to warm white)