I haven't said no because I haven't been able to see what you have done. Photobucket is blocked at work I said what I did to try and make your life a little easier to plan things out. Let me take a peak when I get home.

As far as grounding and the potential for shock, low voltage DC like this doesn't have enough potential to bridge insulating layers like skin, socks, shoes, etc. to make you a ground path. The reason grounding is bad for the driver is the way that the driver keeps the current constant. Some drivers have protection against shorts like this, but it's no guarantee that it will work. There is no good reason to ground the heatsink. If this was AC, then it would be a different story.

got it -- i'm realizing that i can go with solid connections instead of the plugs and they will be wired the same way just permanently instead of plugable. had not considered what would happen if it tried to start up with no load attached. i think this would blow the driver and while maybe unlikely could happen if both plugs were pulled out of spotlights. the benefits of having these plugable are starting to seem diminished when compared to wiring it the same way with solid connections.

Separately, for anyone interested in how to link DIY LEDs to a profilux controller there is a thread on their support form about the meanwells. The quick answer is GHL already makes an adaptor that would connect to the 1-10v dimmer of the meanwell and then from that adaptor plugs directly into the L port of the profilux (so you dont have to create anything you just buy the part and solder it up). there are a few options depending on features but they are part numbers: LB-FAP, EVG AP 2F (for 2 dimmable outlets or 1F for 1).

I was wondering if this PWM controllers can be used with a Meanwell ELN-60-48P?

http://cgi.ebay.com/12-40V-7A-80W-DC-Motor...=item20acdcbbf6

Also is it hard to build one? What will be the cost of DIY one of this? Sorry if this has benn asked before, there are LOTS of post and haven't keep up with the whole thread.

no good because the output voltage is 12-40v and we are looking for 0-10v. i think

The output frequency is too high, as is the same for most of these pwm motor controllers.

It's not too hard to build one. Just take a look at the diagram I have posted. Cost is about $10 if you order parts online (not including shipping).

Here is just a warning about RCA or DC jack connectors. It's nice to have a quick disconnect but it comes with a risk. I've been talking/emailing with Mike at rapidled.com because I have been frying LEDs left and right during my build. We have come to the conclusion that it is because I'm plugging the LEDs into the wall before connecting the DC connectors to the project box. I don't think he will mind me posting his email to me.


"If the driver is powered up, the internal circuitry will have an electrical potential differential (aka voltage) higher than that of the LED string. Completing a circuit equalizes the potential differential -- like lightning. So, if the driver is powered and the circuit is not complete, it will have somewhere between minimum - maximum voltage (9V-48V) on the LED leads. I will assume the voltage will be 48V if there is no load. Completing the circuit will shoot that amount of voltage over the string of leds. So, if you have 3 LEDs in series, and you connect the string after powering, each led will likely get 16V (48/3) and they will all burn out. If there is a string of 12 however, it might not burn them out because each LED will eat up 3.2V = 4V per LED, which is still high.
Another issue is capacitance. The driver has capacitors on it which do a few things electrically. One is regulate flow (amperage). Upon completion of a circuit, a capacitor may discharge at a few amps, so for a split second, the power coming out of the driver may be 48V @ 3-4 amps. This gives us our split second flash.

To put it simply, the potential differential without a load is most likely 48v. Completing the circuit will equalize the voltage across the circuit, meaning 16v per LED, thus burning them out."

Basically, if you don't plug in first you're shooting 48V onto your string. If you do finish your strings and then plug in, the driver will know to regulate the discharge to the proper amount.

Mike

Hi Everyone. this is a great thread and has helped ease the learning curve for led lighting. i currently have a standard 15g (24x12x12) tank that is powered by a 70w MH and 28 PC actinics. its time to replace the bulbs so ive been toying with the idea of replacing them with leds. mounted to the top of my hood it would be roughly 15 inches to the sand bed. im thinking of a 50/50 cree white/royal blue mix in 3 rows of 8 for a total of 24 leds. using two Meanwell ELN-60-48D with a reefkeeper/alc to control them. Id like to be able to achive 150w mh performance (support for SPS and my clams). My main questions are, is this enough leds to achive this output? Will it require optics and what the suggested spacing would be (2" on center?)? Thanks in advance.

Rich

Thanks for posting that. Mike is right. Running a driver on an open circuit is a bad idea. I have posted this a few times over the many LED threads, but it's good to re-enforce that.


24 LEDs is fine, but you can use less if you want. You can easily drop it to 16 (8x2) and get about the same results. Keep the LEDs 2" apart, and the rows 3" apart. Achieving 150W MH performance is no problem even with only 16 LEDs. No need for optics with this setup.

i'm still not sure what to make of this. i am new to electrical wiring so perhaps it's my lack of experience but i thought using a ground was just proper wiring practice. it may be that's its not needed in this case b/c the voltage is low enough, which is comforting to a degree, but how can proper technique be bad for the driver or LEDs? dont understand that part.

as a side note i read in a basic electronics textbook that current as low as 12 mA starts to cause hand muscles to contract and currents upwards of 200 mA are lethal. Most people seem to run the LEDs at 1000mA. However, there is something to be said for the lack of serious accidents that are reported. Particularly considering the headlong method by which most people seem to be jumping into this with no prior knowledge. If it were very dangerous / a ground were required, i might have expected that some of that word might make it's way around.

I'm happy to let the conversation go elsewhere. I have noticed other people posting about this question on other forums so if any of them want to chime in to continue this discussion please go ahead.

EDIT: I can kind of get to the mechanism that would cause the constant current driver to have trouble w/ grounding, sort of. Does that then mean they are fundamentally incompatible w/ a properly grounded system? I didnt know that some devices could have that possibility, but if you try hard enough you can learn something every day

Grounding is a good practice, especially in AC systems. In a system like this, where the driver is controlling the ground loop of the LED string, it can be very bad if you make a mistake on the wiring or attachment of the LEDs to the heatsink. Read around in a lot of the LED threads, and you will see that this is a common problem. If everyone grounded the heatsink, there would be many more costly mistakes, and I don't think as many people would be attempting projects like this.

As far as electric shock, you are right. You can be killed by very little current. Thing is though, you need high voltage to overcome the naturally high resistance of your skin, or a path of least resistance through yousking, like a fresh open wound. You would still need a reasonable ground path at that point too. 24v DC isn't going to do it.

Don't panic. No one has killed themselves from doing this, or set their house on fire. There have been many more instances of fire from MH ballasts or T5 endcap fires than LEDs, and they are thousands of time more prolific than any LED system.

Hey guys,

I have been sitting on my heatsinks for a while, awaiting the funds for the LED's.... which are now ordered . No not literally "sitting" on them


Anyhow, they have a dull surface from superficial tarnishing.


I plan on adhering the PCB's with the Berquist thermal pads.


Should I buff the heatsink? I have buffing wheels with tripoli and white diamond for buffing acrylic to a clear sheen, so this should work on aluminum.

Is it worth it, or can this be skipped?

It can't hurt. If the surface is tarnished, it's not so bad. If the surface was scratched, then sanding and polishing would be a very good idea. Buffing it to a high polish will look sharp, no matter what.

Or you could just try this!

http://www.lumenaltlighting.com/products.html

OK, I can buff them. This thing will be in my canopy, so no need to bling it out... .but if it can help the performance of the thermal pads, all the better.

Hey guys I'm looking for a fan to go over a 8"x8" heatsink with 23 LEDs I'd like to have a big fan (footprint) but low profile (no more than 3/4" high). Don't understand much about CFM and Db in terms of what should I be looking at. I saw some 140mm fans but apparently the bigger it is the slower it runs and I'm afraid it might not be enough to keep it cool. How this sounds to you guys?

Fan dimension 139 x 139 x 25mm
Fan speed 1000 R.P.M.
Fan airflow 23.19 CFM
Noise level 19.5 dB(A)
Fan air pressure 1.49mm H20
Fan life expectancy 30000/hrs
Bearing type Sleeve Bearing

Another option might be two 80mm fans to cover almost the 8" length of the heatsink but I prefer a larger one

You don't need much. An 8"x8" heasink could easily be cooled by a 10cfm fan. Go as big as you feel comfortable with, and keep the db's under 25 if you want it really quiet. Beyond that, go wild.

Hey y'all,

I'm building a wood enclosure for my LED's heatsink (2" wide, 24" long heatsink) with a dado to accept the plexi shield.


I need to know how much clearance I need to allow for optics, should I decide to add them later? Ie, once the LED/PCB + optic is mounted to the heatsink, how much room in between the heatsink surface and the acrylic shield should I allow?

From heatsink to plexi, 3/4"

sweet, thanks!

Hi - this thread has gotten so long I'm afraid it would take me hours to get through it so I'll ask a dumb question...can these bulbs I see here work? Also it seems all these LEDs are white only...where can you buy the actinic (blue) leds or are plain white LEDS enough? Thanks
http://www.elementalled.com/LED-Lighting/LED-Light-Bulbs
http://www.ledlightsworld.com/par30-7x1w-l...bulb-p-100.html

added- might have answered m own question but is the issue with these commercial bulbs that they are very low K ratings...2500 to 5000K or so?

ALSO---

I am about to order a 12v 150mA Lucent power supply from MPJA.

I think I also need some heatshrink tubing, as i do not have any right now. What size tubing do I need?
I will be using 20 AWG multistrand.


Here is what I have, is there anything else from MJPA I should order?


LED's, Meanwell "D", heatsink
drop cord for Meanwell plug
470 and 1K ohm resistors (1/8 W)
10K pot
.1 and 1f capacitors
LM317
63/37 solder
soldering gun w/fine tip



Anything else? I need some flux and a cheap circuit board, which MJPA doesn't carry.









I can only answer your question since I've gone down that road sooooo many times.

In short, those that you linked to generally are not strong enough, and the few that are (the ones with 3W LED's) aren't guaranteed to last, nor do you always know what you're getting. Plus, in general, to get the output that you need, you'd have to sink an insane amount of money into them.


A DIY LED array leaves you so many more options.


As for the blues, yes, the blues are very easy to find. The Royal Blues are what you are looking for. I just ordered (and received) mine from here, and can't wait to put it all together.

http://www.nanotuners.com/index.php?cPath=...o92sbs38j24c005

is it more advantageous to have taller heatsink fins or a thicker surface interface (between leds and fins) when using active cooling?

Its been a few weeks since I have read through the whole post and came up with a question I'm not sure has been answered. Will thermal adhesives such as THIS be sufficient to bond the LEDs to a Heat Sink without Tapping the heatsink and screwing each LED in?

I don't have a tap and die, so this would make life much easier, just not sure if it would be as effective.

Yes. Rather permanently too.

Thank you. For this project, I plan to keep it a small 8-10 LED set-up and having it attached like this would be fine.

Doesn't really matter much. The thickness of the interface surface only aides in heat saturation (the amount of time it takes for the heatsink to reach a stable temp). Taller fins wold be a problem with passive cooling, but with active cooling, they pose no problem.


With the epoxy, you still need to make sure that the amount of epoxy between the star and heatsink. Pressure on the star as the epoxy cures will help. Thermal pads get the job done the same, but with less mess and far quicker.

is this good for a 2.5g AGA pico
2 white Cree XR-E Q4 Star LED

4 blue Cree XR-E Q4 Star LED

1 Power Supply 12VDC 3.0A

2 3023-D-E-1000P Wired BuckPuck, 1000mA Output, DC Powered w/ Potentiometer
i also need to know what size heat sink to get

Get two more whites. The 8 LEDs will help with coverage, and going 50/50 will make it easier to blend colors. Use the pots on the drivers to get your desired color temp.

For heatsink, get as big as you feel comfortable with.

Hello,

I'm gonna build a voltage regulator circuit based on a LM317 to supply 10V for my 2 MeanWell drivers. Do you think one circuit would be fine (connecting the 2 drivers in parallel to the output) or do I need 2 circuits ?

I have another question. I'll use an Arduino for dimming. Can I use the same 12V power supply for the LM317 circuit and for the arduino ? Or is it better to use 2 separate power supplies ?

Both circuits you are describing are for dimming. I don't think you need the 10v LM317 w/potentiometer circuit and an arduino.

If you are, perhaps, thinking the 10v power supply issue is for actual power to the driver and LED's, it's not--- the Meanwell runs off of mains power. The 10v is just input "signal" for the dimmer.

I'm sorry, I didn't make myself clear.

I won't use the LM317 circuit for dimming but for supplying 10V to the Arduino, since Arduino's ouputs deliver 5V only (i intend to replace the pot by a simple 10K resistor).

You can use the same supply to provide the 10v for the dimming, and the 5-9v for the Arduino.

I'm having problems getting a 12 LED string to turn on with a Meanwell ELN60-48P

Wired LEDs in series. Double checked everything but when I fire it up it wont turn up. When I turn it off after 4 or 5 seconds they all dim from low to high (Just like my signature) and then turn off. Tried leaving it On for a couple of seconds but nothing happens. What am I doing wrong?

quick question whats the difference between the
Cree Q4 XR-E Cool White LEDs
and the Cree Q5 XR-E Cool White LEDs

Q5 is about 7% more output @350ma.

HTH

Chris

thanks!

Evil, what current does the Power supply need to provide for everything to run well (the LM317 circuit for the 2 drivers and the power for Arduino) ? 1 A ? More ? Less ? Because I guess if the current is too low it won't work well.

What are you using for dimming input?


1A will be more than enough. The current requirements for two driver and the Arduino will be less than 100mA.

I found out. I left the dimming inputs with nothing so it won't turn on. The driver will recognize that as a 0% PWM signal right? So no power unless I hook a power supply to get at least ON/OFF with no dimming

Thanks Evil for you reply.

As for fans, I've been hesitating between one 12mm fan that is rated 45 CFM at 21 dB and two 80mm fans that are rated 19 RPM at 15 dB each. For a 12'x8' heatsink, what is the better option to you ?

Also, how do you guys run your fans ? All day long ? Only when the white leds are on ? Or when it gets too hot ? Because maintaining the heatsink temperature as stable as possible is better for the leds, rite ? I'm asking this question because I don't know if I'm over complicating things trying to control the fan speed with PWM in function of the heatsink temperature. Maybe letting the fan on when the leds on is just as good...

Correct.


It probably won't make much difference. You could use the 2 80mm fans to cover a wider area along the width of the heatsink to have more airflow down more of the fins.

Fans are on when LEDs are on. Many times the fans are tied in with the power supply running the blue LEDs, as when you are doing dawn/dusk effects, they are the first on and last off. When it comes to heatsink temps, cooler the better. You don't need to keep the temps steady.

Since, I'm going for 2 Meanwell ELN-60-48P drivers (delivers 48V) and 12 leds on each, I think it won't have enough voltage to wire the fans in series. Could I wire in parallel instead or is it too risky for the leds, like for wiring the leds in parallel ?

Where you thinking to wire the fans? You will need a power supply for the fans if you are using meanwells

Alright, I need to understand how this thing works...As I said before, I want to dim the leds using Arduino. Since its digital ouputs can only supply 5V (PWM mode) and since the drivers I'll be using (Meanwell ELN-60-48P) need up to 10V for dimming, I need to build a circuit based on a LM317 circuit, that will allow to get a 10V output, and a PNP transistor used as a switch.

If I got it well, if the transistor is saturated (on), it means Meanwell's DIM+ pin gets 10V. Now if the transistor is blocked (off), how much does DIM+ get ? 5V ? 0 ?

Please tell me if I'm wrong.

Thanks in advance !

As Sammy said, you can't run the fans on the Meanwells.


When the Arduino output is high, 10v to the driver. When the output is low, 0v to the driver.

Thanks Evil. That means when Arduino output goes from 0 (0V) to 100% (5V), driver gets 0 all the way up to 10V right (this is linear, not a binary state) ?

It's binary (on/off). A true frequency to voltage conversion is a lot harder. All you are doing here is converting a 5v signal into a 10v signal.

I have another question. If I'm to put a On/Off switch to each driver and both meanwells are connected together in the same power cord, can I interrupt the positive cable from the meanwell to the LEDs or should I do it in the power cable to the wall plug (then will need independent cables for each driver)?

You can do both. There will still be some power usage is you just turn the dimmer off, so keep that in mind if that's a concern.