Evil (or anyone),

I was working with National Semi's Webench (http://www.national.com/analog/webench - a great resource for diy wannabees) and one of the designs is attached, my question is...just want to confirm that the lines on the left connect to Vin and Grd and on the right to led+ and led- ?
Click to view attachment

Thanks.

You are correct.

Hello all.

I just what to express that this is an excelent topic ( and forum ).

I'm just new to this hobby and researching hevilly before doing the junt. O would like to request some help.

I would like to do an LED illumination for my aquarium ( reef aquarium with corals and fish ), but i'm a little bit lost. I know that the Cree XR-E are the ones that i should use at the moment, but don't know the number and the lens ( wich degree lens to use if i need it)

I'm going to get an aquarium about ( in centimeters ) 100x30x40.

For what i could read I believe that 10*8*10 LED would be enought using

W B W B W B W B W B
W B W B W B W B
W B W B W B W B W B


Please advise since i'm quite new in this.

Congrats again for the excelent toppic and also the excelent thread where you are building your set!!!

Regards,
Rui

Your tank is pretty narrow and long. 10 LEDs down the length isn't going to quite be enough to cover the tank without spotlighting. 15 would be better at 2" spacing. Because your tank is narrow though, you can get away with two rows instead of three. This is only 2 LEDs more than you had planned.

Take the $5 Biocube 29 Heat Sink Challenge!

I have seen GR8 Drawings to to use to mark your Biocube 14 so you can start drilling your heatsink.

But there is not one for the Biocube 29 Gal.

So,

I will paypal $5 dinero, That is $5 big ones to the person that can post a PDF for a heatsink 7.29x14 inches. Holding 24 LED.

Not only will you be getting the Big $$$ you will help many in the DIY community.

Hi evilc66.This is the lost day for group order,you have any good news with the Meanwell driver??
(1-10v)for control with Profilux??Thank you

I was busy all day yesterday. I should have an answer this afternoon some time once I am done with yard work.

Thank you am waiting

Hi,

what do you think of this? http://www.ampoule-leds.fr/neons-led-etanc...29_94-fd-3.html

They are marked as having 12.000 kalvin and having a lens for 150º.

I see some users getting solutions with smaller led's than the CREE XR-E and getting also good results.

Can you please explain the reason to choose the CREE ones, quality? livespan? help me

Thanks,
RR

Power is the primary reason. The LEDs used in those strip are what are called superflux LEDs. They are pretty high output for the current used, but they still don't have the power to penetrate deep tanks. The wattage used on those LEDs will only make them good for very shallow tanks, and will be considered not much better than power compacts for the same application.

For power LEDs like Crees, it is very easy to create light similar in intensity to a 70W, 150W, or 250W MH using only a handfull of LEDs per square foot. These LEDs are also rated for longer life and better lumen maintenance.

I am thinking about doing LED lighting for a new 15 gallon setup I am working on; the tank is going to be 24 x 12.5 x 12.5. Do you think I could get away with 2 rows, about 3-3.5" apart of 10 or 11 leds each? It would be placed an inch or two back from the center line of the tank since most of the stuff will be in the rear 3/4 of the tank. Also with my planned setup it would not be an issue at all to point the two rows a couple degrees off of straight down if necessary.

If I end up going with a 20 gallon (same footprint, ~4" taller) would the same setup work with 60 degree lenses?

BTW I'm fairly new to SW but can do whatever needed with the electronics, most likely going to make my own drivers and I can run the LEDs a little over 1000ma if it helps.

TY in advance!

Another schematic question...

I want to generate a pwm signal using a pot and came across the following SG 3235 circuit :

Click to view attachment

What would represent the 0-5v demand input line - could this be replaced with a 5v supply through a voltage regulator ?

Would this be better than a dual 555 circuit ?

Thanks.

What chip is that? I've never heard of a SG 3235 chip. Do you have a datasheet for it? The schematic picture was too fuzzy to make out everything.

Datasheet... http://www.onsemi.com/pub_link/Collateral/SG3525A-D.PDF
Link to original article describing circuit (section 2.3) ...
http://homepages.which.net/~paul.hills/Cir...Generators.html

Thanks.

That PWM driver is more complicated than you need, and also its not widely available so you would have some trouble finding it. I would just go with a dual 555 timer to create the circuit. its cheap, easy to get, and there is tons more documentation about it on the web. the 555 datasheet has guidelines on making a pulse width modulator out of it: http://www.national.com/ds/LM/LM555.pdf
good luck

The demand (pin2) is the enable pin for lack of a better word. It's a non-inverting input, so 0v is off, and 5v is on. There is also an inverting input (pin1) where 0v is on and 5v is off. If you want it on all the time, leave pin2 floating and ground pin1.

This chip may not be able to set your duty cycle independant of the frequency. I see no way to set the duty cycle, as the pot changes the output frequency.

scratch the part of them being hard to find... i was typing in the wrong part number in the search. if you do want to go with that circuit. it think that 0-5v demand signal is what controls the pulse width. connect your pot between +5v and GND and then connect the wiper terminal to the IN+ pin (0-5V demand). when you vary the pot it should vary the pulse widths

OK, I'll go back to the 555 circuit instead...what would be your recommendations for a circuit to ramp up a pwm signal from around 0% to 100% automatically over a 2 hour period - any not requiring mcu programming ?

Cheers.

I'm thinking about doing something similar for my system, a mosfet with some high value resistors and capacitors should be able to do just that but it will take quite a bit of fiddling and it will never be as linear as a simple PIC program could do it. Also the circuit will be pretty sensitive to humidity and salt and eventually it will most likely get stuck either on or off - neither of which are good things. I'll mess around with it at some point though and post my findings.

Hi All

After many happy hours trawling the net for information on DIY LED's I have come across this thread and can I just say a big thanks for all who have posted info.

I am about to set up a tank 48"L x 24"H x 18"W I am considering building 2 LED arrays in place of 2 150w MH could you please advice as to be best way to go.

Once again many thanks to all who have posted.

The capacitor you would have to use to delay that ramp up would be huge. Do do it effectively, consistantly, and safely is with a microcontroller.



Best way to go is to have the heatsinks cover as much of the length as possible. This will give the most coverage, and even lighting. Going with smaller pods to recreate the MH setup will lead to darker areas in the center of the tank. It doesn't take much more effort to make the array a little larger to spread the light out more.

Any chance you can cover how to adjust the color temperature by dimming? I think it's done by changing the intensity of some leds (i.e. the white ones) while leaving the others on full. You know the wavelength of the leds but how does it all add up to give you CCT? Is there some formula used here? Thanks.

It's all in the balance of white and blue, and it's all by eye. There is no magic formula to hit a certain color temp. Just set it to what looks good to you.

So I've read this whole thread plus various other LED threads. I'm thinking about replacing the 150w MH in my JBJ 28 HWI with a LED setup. Obviously I don't want to just replace the MH...I gotta upgrade to something equivalent to 200-250w of MH light.

If 24 LEDs would produce ~150w of output, then I'd need ~40 LEDs for ~250w. Does that sounds right? And I'd need 40 degree lenses for each. And if I'm doing 20 white LEDs and 20 RBs, then I'd need 4 MeanWell drivers. 4 drivers is kind of expensive. Can you suggest a better setup for driving these 40 LEDs and controlling the RB LEDs separately?

For what it's worth, the JBJ is 18" x 22" x 22". I believe the canopy is 18" x 19" but that's just a guess since I'm at work and the tank is at home.

Does this plan sound reasonable? Got any suggestions? Thanks much!

How much PAR do the Royal Blues alone have?

Keith

Any real reason you want to go all the way to 250W levels? Thats a lot of light in a little area. Your biggest limitation is the area that you can fit a heatsink, and mount LEDs. Once you step to 40 degree lenses, it really reduces the area that is covered, and would normally need a larger area covered by LEDs. You don't have that larger area. 24 LEDs with 60 degree LEDs will be able to keep damn near anything you would like.




Quite a lot. From the tests I have done, royals produce just about as much PAR per watt as a cool white. It's difficult to say exactly how close they are, as most PAR meters are less sensitive in the blue range, and the results are reported low.

Hey Evil, I bough a 24V 5A power supply for my 12 LEDS and a 24.5V fan for the heatsink just in case I can do something with it. Is there a way that I can plug it to the power supply also so when the lights go on the fan also? BTW when you have a break, take a look at my tank build, there are some pics of the LED lamp design and I would like your feedback I'm crazy to start the lamp build!

Just hook the fan to the power supply. Fan comes on when the LEDs come on.

:-)

starting to fell bad about always being requesting help :S


I'm not much on electronics, and the few university classes about the subject that i had already have several years ( need to find the books to read again... should had paid more attention :S )...

But, i was searching and found this driver , don't think its too expensive, but please give your oppinion. For what i had read i can place 16 1 Watt CREE XR-E or LUMIX K2 Also i believe i could manage do dimm the leds using this controller with the PWM using an arduino right?


Thanks again for you pacience

Rui

Not a bad little device. Little pricey though. You will be able to drive a max of 10 white or blue LEDs, not 16. It's an issue of the forward voltage, not the wattage. This can easily be dimmed by an Arduino or similar controller.

Humm, just 10 leds per devide.... That would be costy...

Do you know some other driver that would be cheaper?

I was looking at the www.national.com site, but i believe i don't have knowledge to mount one driver myself :/. At least in the near future it's not an option.

Can you please advise on a cheaper driver ( dimmable or not).

Best Regards,
Rui

Well, it's better than 6 on a Buckpuck.

There aren't many choices currently available for high LED count dimmable drivers. One that we are starting to use is the Meanwell ELN series. They are line voltage (AC) with a dimming option, and a lot of power for large arrays. They are certainly not as cheap as the driver you showed.

How many watts are Cree Royal Blues? I know BuckPucks can run 18@1w and 6@3w. I'm guessing they are 3w. I plan to do a custom probably 6-Royal Blue Cree LED supplement on my Sunpod. So one buckpuck should be fine? What mA output would be best?

You can run the rbs at either 750ma or 1000ma.

Any pros/cons on running them at lower/higher

Pros: More light
Cons: More heat, change in color?

If I remember right there isn't much of a noticable drop in par of the rbs at 750ma. I'm sure they will run a little cooler, doubt there will be much color change.

Oh okay, in that case looks like 750mA it is, strictly actinic supplement so wont need potentiometer for dimming. Now to decide how to wire them (parallel/series), mounting, heatsink

You always want to run strictly in series whenever possible. Running in parallel creates issues with voltage inequalities, and problems with failures. Also, you divide the current up between each parallel string, so you aren't getting 750mA to each LED anymore.

Careful with the statement of using 18 1W LEDs on a Buckpuck. This is understood as running 3 parallel strings of 6 LEDs. You are always limited to 6 LEDs in any series string. Like I said before, you always want to run stricktly in series whenever possible.

Ah, okay thanks for clearing that up for me.

I'm taking Electricity & Magnetism Physics right now so I dont know too much about circuits.

Are LEDs considered resistors or capacitors? Or neither?

I remember for resistors in series: Voltage is constant, and in parallel: Current is constant, which sounds like it should apply to LEDs as well by your explanation.

Would 6 Cree in series be acceptable for one Buckpuck or would current drop substantially over the circuit?

LEDs are diodes (Light Emitting Diode).

You have it backwards. All devices in a series circuit will have the same current. 1 LED or 6 LEDs in series will run at 1000mA if thats what the driver is set at. All devices in a series circuit will have a voltage drop across each device. That total voltage drop has to be equal to the source voltage (which is variable from the driver to match the changing voltage drops across the LEDs).

Me again

still analysing the led DIY possibility and due to the startup price i was thinking in doing just half now for the first beguining of the aquarium ( build of the stand, aquarium, rock cycle and so on). Also would not invest the full value and first try with half.


I was looking in the led-tech and made this small list:


-> was checking the Luxeon. write ones for 10.000 Kalvin , blue one on 12000 kalvin using 500mA
LT-0955, Luxeon 1W Emitter , LT-0959, Luxeon 1W Emitter .

Should i go for the CREE ones for the bigger Lumen? and my question would be, aint the Kalvin enought? ( im confuse :S )

LT-1279, Power Supply for 6-10x 1W LEDs (230V). if i would stay with the Luxeon, this would be enought. But not for the Cree ones since it goes only to 750mA.


LT-1205, Heat Sink for 10mm PCBs (by the meter)
Was thinking in using a row like this, place underneat the stars. Is it a good idea?


Hope i'm not being too anoying :S

Regards,
Rui

For a tank of your size, you need to run at a minimum of 750mA, no matter the LED. Ideally, you should be running Luxeon K2/Rebels, or Cree XR-E LEDs. Any of these LEDs can be run at this current. You may be looking at 1W LEDs to save some money, but you need the power to get a decent amount of light into the tank. There is no cheap way to do LEDs for a tank.

Hi evilc66,

Is it save or recommended to power up 2 string of 9 LEDs (parallel) from a constant current PS ? eg Meanwell ELN-60-27

or should I get ELN-60-48 to power 16 Leds?

Mind sharing what's the pro and con for both ?

Thanks.

Well, to begin with, you can't do either of what you are asking. The ELN-60-27 can only do 7 LEDs in series (assuming a 3.7v forward voltage for white and blue LEDs), and the ELN-60-48 can only do 13. At that point, I don't think one additional LED is worth the effort of trying to safely run strings in parallel. Current mirrors, while simple and cheap, will be required at the end of each pair of parallel strings to prevent additional failure if one LED dies.

Is an 8.5" width heatsink too narrow for an 18" wide tank? The tank is 36 x 18 x 25 and per Evil's recommendation I will be using 90 LEDs with 40 degree optics. In planning my hood I started thinking that the 8.5" heatsink from heatsink USA will be too narrow and that 10.5" might be the minimum. If so, what width would be optimal?

Hi there. I've ordered 6 ssc royal blue leds that come premounted on a board. I have one of these lying around and was wondering if it could be use to run them.
http://www.internethobbies.com/lgbanthrotin.html

I am not adept in electronics but since the voltage can be varied does it mean I will be able to dim the leds with the throttle?

I don't know much about model trains but I would guess that the speed is controlled by varying the voltage. With LEDs, the intensity is controlled by varying the current. So I would say that you could not run LEDs off of it. You might be able to use it as an external dimmer control for a meanwell driver but it probably wouldn't be a good idea since the max voltage is 10 on these drivers.

Thanks for the reply. Guess I have to find something else.

Razor,
This is what I'll be using. Meanwell driver http://www.meanwell.com/search/ELN-60/ELN-60-spec.pdf
and this as a dimmer http://www.dimensionengineering.com/DE-SWADJ.htm

Since you are only using 6 LED you could always use a single adjustable buck puck and separate power supply.
There is a lot of good information on this website if you'll read through the threads. It takes awhile but can teach you everything you need to know to do it. I started out knowing nothing and have learned tons.

Here is a good thread on power supplies. http://www.nano-reef.com/forums/index.php?showtopic=183692

Hey Evil. I have a question.

I was only able to afford 2 drivers in the gb and 12 of each led.

What I would like to do is to make six 4 led lights (2&2)all powered off of the 2 drivers. Is this possible?

If it is possible would I then be able to add 2 pots to each unit and then make them dimmable on each channel as well?

Also how do you power fans?

Thanks