DIY LED - need help with the layout (images) - The Planted Tank Forum
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post #1 of 35 (permalink) Old 10-13-2014, 05:07 PM Thread Starter
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DIY LED - need help with the layout (images)

I have a 20x6 inch heatsink over a 20g planted, and 6500k, red 660nm, blue 450nm and green leds. All leds are 3W.

Would this be an ok layout for a planted tank? I do not have CO2, nor do I dose nutrients at this moment, but maybe I will in the future.

Any suggestions are welcome. Thanks.



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post #2 of 35 (permalink) Old 10-13-2014, 05:17 PM
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So, that's 25 Leds.. is the 3 watts total or 3 watts per LED?

Assuming 3w per LED, that's 75w of LED light, which is a lot more light than 75w of T8 tubes (which would still be a lot on a 20 with no CO2).

Since you are not doing CO2, make sure you build a dimmer into your design. You are going to want to run those LED's pretty low (maybe 15-25%), unless you hang the light pretty high above the tank.
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post #3 of 35 (permalink) Old 10-13-2014, 05:38 PM
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Quote:
Originally Posted by gabriel.mi View Post
I have a 20x6 inch heatsink over a 20g planted, and 6500k, red 660nm, blue 450nm and green leds. All leds are 3W.

Would this be an ok layout for a planted tank? I do not have CO2, nor do I dose nutrients at this moment, but maybe I will in the future.

Any suggestions are welcome. Thanks.



Are you running any separate channels???
Off the cuff comment is too much red.. Substitute cyan for green and cluster red/blue/cyan together..
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post #4 of 35 (permalink) Old 10-13-2014, 07:05 PM Thread Starter
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LEDs are 3w each, every channel dimmable. I will not run them at full power at least for now.

The 10 white led's will be the brightest ones, at 160-200 lm/led, with the red ones at 30lm/led and the blue ones a bit brighter (100lm/led?) at full power.

I plan as channels:
- white
- blue/red (for growth/color accents)
- eventually in the future one/two blue led as nightlight

I will probably purchase some cyan later.

Basically give up the green, reduce the red, group into clusters...
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post #5 of 35 (permalink) Old 10-13-2014, 08:32 PM
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Quote:
Originally Posted by gabriel.mi View Post

I plan as channels:
- white
- blue/red (for growth/color accents)
- eventually in the future one/two blue led as nightlight
I would never encourage anyone to put the red and blue on one channel..
If you want to cut it down to 2 channels I suggest a red/white channel and a blue/white channel..
The red/white channel being composed of low k LED's i.e 3500k and red.
The blue/white channel being 6500k white or better..

As a start a 2:1 w/r and 2/1 blue/red ratio is a good start..
Same way reefers run blue and white channels for color balance..
Technically a 2 channel design of ww and cw led's is all that is needed:



What is always missing is cyan............
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post #6 of 35 (permalink) Old 10-13-2014, 09:09 PM Thread Starter
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Ok, I will keep the red/blue separated for now. I would actually plan on using two RGB controllers in the end (I have one now) that can output 12V/2A max/channel, with remote control (those controllers used for RGB led strips). They seem to be working pretty well for 2 white LEDs in series.

I will tap the heatsink so it will be easy to upgrade for future use (mount, changeLED's), and in the future I will get some warm wites, more blue LED's and a couple of cyans. I'll just have to mount it and see how it looks for now.

Thank you for the chart and for the advice. I consulted lots of resources, but any piece of advice is a bit extra.
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post #7 of 35 (permalink) Old 10-13-2014, 10:37 PM
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Originally Posted by gabriel.mi View Post
Ok, I will keep the red/blue separated for now. I would actually plan on using two RGB controllers in the end (I have one now) that can output 12V/2A max/channel, with remote control (those controllers used for RGB led strips). They seem to be working pretty well for 2 white LEDs in series.

I will tap the heatsink so it will be easy to upgrade for future use (mount, changeLED's), and in the future I will get some warm wites, more blue LED's and a couple of cyans. I'll just have to mount it and see how it looks for now.

Thank you for the chart and for the advice. I consulted lots of resources, but any piece of advice is a bit extra.
Those are meant for constant voltage LED "strings"... They will not work "well" w/ 3W emitters unless you keep each string in the 12V V(f) range..
That would be like 3= 3w in series then enough of those strings to keep the current in check.. 2 or more depending on what current you want..

Generally each string of 3 will need a "current limiting" resistor..

IF I understand what you have correctly, you are taking the "hard way" about this..

Constant current drivers w/ PWM dimming and a controller is more the way to go.
A Typhon or one of the "like" controllers is a better, easier, and safer way to go.
,
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post #8 of 35 (permalink) Old 10-14-2014, 03:41 AM Thread Starter
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Yes, I know. I am keeping the strings in the 3V range, that's the only way I can be sure it works. I did some measurements (A and V) from 0 to 20 steps (every channel goes up to 24 steps if I remember correctly), and around step 17 I got around 700mA (I don't remember the voltage, I must have it on a paper somewhere). I have some electronics experience and I am trying to keep my power supplies, drivers and LEDs safe . The red LEDs are opening up a bit quicker, so I will have to put probably 4 of them in series. I will make some measurements and maybe I will use some resistors so I can max out the drive (step 24 on the remote) without killing it or the LEDs.

I will have to go with the drive I have for now, but as you say, I envision using constant current, pwm controllable drivers in the future, controlled by an Arduino, together with other aquarium functions. I do have plans for the future, but for now I want to deal with what I have.
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post #9 of 35 (permalink) Old 10-14-2014, 04:05 AM
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Are you going to hang the light fixture so it can be raised and lowered? If you do, you will probably want optics on the LEDs so you won't get so much spillover light as you raise them. However, that also reduces how much dimmer the light is when raised. You could also use a "lamp shade" over the heatsink, so it would stop the spillover light from blinding anyone looking at the tank.

Hoppy
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post #10 of 35 (permalink) Old 10-14-2014, 04:48 AM
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Quote:
Originally Posted by gabriel.mi View Post
Yes, I know. I am keeping the strings in the 3V range, that's the only way I can be sure it works. I did some measurements (A and V) from 0 to 20 steps (every channel goes up to 24 steps if I remember correctly), and around step 17 I got around 700mA (I don't remember the voltage, I must have it on a paper somewhere). I have some electronics experience and I am trying to keep my power supplies, drivers and LEDs safe . The red LEDs are opening up a bit quicker, so I will have to put probably 4 of them in series. I will make some measurements and maybe I will use some resistors so I can max out the drive (step 24 on the remote) without killing it or the LEDs.

I will have to go with the drive I have for now, but as you say, I envision using constant current, pwm controllable drivers in the future, controlled by an Arduino, together with other aquarium functions. I do have plans for the future, but for now I want to deal with what I have.
your missing a minor point. The "dimmer" doesn't change current.. it only pulses it. It may average to 700mA but it is feeding all it can to the LEd's...
At least this is how the more common "strip" devices work..
W/out th current limiting resistors all you are doing is pulsing 2A.. or whatever your PS can put out if you are not exceeding the V(f) requirement.. and you won't w/ 3 or less LED's..
In other words it is like 2A w/ a 50% duty cycle averaging to 1A over time.
As an example w/ "real world" LED's.. This is a circuit for a Cree xp-e using a 12v constant voltage power supply. Your PS could only run 2 3 diode series strings in parallel and you will max out the 2A ps..



The resistors function is to drop the 12v to 10.5V....which is the voltage that creates the 1000mA "draw"..

you will need a 1.5Ohm 1.5W resistor for every 3 LED's and 1A per every "set" of three run in parallel....
Yes by limiting your pulse width (duty cycle) to under full out you can control it.. but not very elegantly..
Illustration:

Quote:
Figure 2: Internally generated PWM signal and LED current for the application in Figure 1
The amplitude doesn't change (1A).......... only the period.. which is how most of these dimmers work.. Cutting into the cycle
The V(dim) is just the signal.. not the drive current or voltage..

without knowing your exact "dimmer" and its inner workings I can't 100% guarantee the above is correct.. but I'm fairly confident that this is how it works..
Overloading the ps is a way to control the current..

regarding "deep red" and using Luxeons as an example:
Quote:
Forward Voltage is 2.20V @ 350ma, 2.3V @700ma

Last edited by jeffkrol; 10-14-2014 at 05:35 AM. Reason: data
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post #11 of 35 (permalink) Old 10-14-2014, 04:43 PM Thread Starter
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Originally Posted by Hoppy View Post
Are you going to hang the light fixture so it can be raised and lowered? If you do, you will probably want optics on the LEDs so you won't get so much spillover light as you raise them. However, that also reduces how much dimmer the light is when raised. You could also use a "lamp shade" over the heatsink, so it would stop the spillover light from blinding anyone looking at the tank.
The fixture is going to be hanging, I have 60 degrees lens for the LEDs and sort of a box made out of wood - the heatsink drops from the top in it.

Quote:
Originally Posted by jeffkrol View Post
your missing a minor point. The "dimmer" doesn't change current.. it only pulses it. It may average to 700mA but it is feeding all it can to the LEd's...
I wasn't sure on how those drivers work... so they have a PWM output from 0 to Vmax (12 V in this case). That would explain the pretty linear V/A output (from my point of view, measured with a multimeter).

Well, I assume for now, if I keep everything at decent levels it should be ok, until I get some decent drivers.

Is that calculator you used an online application? If yes, and if it's free, could I have the link? Thanks.
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post #12 of 35 (permalink) Old 10-14-2014, 06:47 PM
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Originally Posted by gabriel.mi View Post
The fixture is going to be hanging, I have 60 degrees lens for the LEDs and sort of a box made out of wood - the heatsink drops from the top in it.



I wasn't sure on how those drivers work... so they have a PWM output from 0 to Vmax (12 V in this case). That would explain the pretty linear V/A output (from my point of view, measured with a multimeter).

Well, I assume for now, if I keep everything at decent levels it should be ok, until I get some decent drivers.

Is that calculator you used an online application? If yes, and if it's free, could I have the link? Thanks.
your concept is fine.. Beamsworks LED's are all based on constant voltage.. for the bigger ones (1-3W) they do use a 15V ps and 4 LED's in series/ and parallel.. Almost all their lights have LED counts divisable by 4..

IF you are going to do your above array, I'd suggest a variable voltage constant PS .. or you will have a bottleneck.. You are fairly limited w/ 2A.. About 6 @1000mA.. [email protected] 500mA

http://led.linear1.org/led.wiz
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post #13 of 35 (permalink) Old 10-15-2014, 02:40 PM Thread Starter
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Jeff, I have a question: if I buy a Meanwell driver, or other reputable dimmable driver, is the output going to be a PWM, or linear? I thought I might ask, since you know quite a few things about these drivers.
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post #14 of 35 (permalink) Old 10-15-2014, 05:28 PM
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Quote:
Originally Posted by gabriel.mi View Post
Jeff, I have a question: if I buy a Meanwell driver, or other reputable dimmable driver, is the output going to be a PWM, or linear? I thought I might ask, since you know quite a few things about these drivers.
Very few are "linear"... most output a pulsed drive current..
Your major choice is in the type of "signal".. PWM, 10V or potentiometer..
That will determine (or vice versa) what controller you will use..

People often confuse input w/ output..
A good "primer' on what I'm getting at:

http://www.ultimatereef.net/forums/s....php?p=6535081



OUTPUT:


INPUT:


Quote:
It seems to make sense to dim light by pulsing max amp and not by lowering the amp value in order to prevent colour shift associated with running LED at different current.

Probably the disappointment for some will come from the fact that actually the led is at full power, drawing MAX amps (1A if Meanwell LDD-1000H / XPPOWER LDU5660S1000) during the ON time instead of operating at a lower current, which I believe was one of the important things.

Last edited by jeffkrol; 10-15-2014 at 05:32 PM. Reason: rext
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post #15 of 35 (permalink) Old 10-16-2014, 12:57 AM Thread Starter
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Niiiice, it's always nice to talk to someone who speaks a language I understand . Thanks.
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