DIY LED driver for reef lighting

[reefocean]

Hi

I don't really want to interrupt but..

I have been skimming this thread, and I want to have driver/dimmer assembly made that can work with Arduino. I am not expert by any means and most of this thread goes over my head.

I am interested in seeing terahz final product after the dimming issue is solved and I really like der wille zur macht boost design at the beginning of the thread.

Now I need to run about 32 three watt crees and (8) 10-15 watt bridgelux cool whites. All of them drive at 1amp (the Bridglux I am looking at actually drive at 1.05 amps and top out between 2-2.5)

I have notice that many ideas have been put forward, and several members have created or are creating their own designs.

Which design would be best for maximizing the LEDs per circuit. It prefer the blues to be on 2 and the whites to be on 2. Making 4 circuits. I would also like the dimmer to control each circuit separately. Id prefer buck if that is possible, I would prefer to have the flexibility to change the amounts of LEDs (reduce) if I would like. At the same time, I would like a 24v power supply but 48 is fine too. I just find it hard sifting through all of this info, most of which I don't understand.

Also, if there has been a dimmer module designed for the drivers, Id appreciate the docs on that too...if you don't mind sharing. I will be having the boards redesigned for my needs (space etc). If that is alright too. I would obviously credit you for the initial design

As I understand it goes power supply to dimmer module, dimmer module to controller and drivers, drivers to LED boards.

Any help would be appreciated. I will also be having code made for the Arduino, and will share once that is done...if that at all a good bribe for helping me out :lol2:

Thanks

 

[terahz]

I am interested in seeing terahz final product after the dimming issue is solved and I really like der wille zur macht boost design at the beginning of the thread.

PWM dimming worked even on rev 0.3. This is your basic straight arduino analogWrite(pin,0-255). Analog dimming requires an analog signal, which you don't get out of the box with arduino micros. You need a filter to convert the PWM into proper analog voltage. This part works as of rev 0.4.

Which design would be best for maximizing the LEDs per circuit.

Since the LM3409HV chip can go up to 74V and unto 5A, I'd say that is as good as it gets on a single chip at this point.

Now I need to run about 32 three watt crees and (8) 10-15 watt bridgelux cool whites.
<snip>
It prefer the blues to be on 2 and the whites to be on 2. Making 4 circuits.
<snip>
At the same time, I would like a 24v power supply but 48 is fine too.

Unfortunately it isn't that easy. 32 LEDs with avg 3Vfw is almost 100V. In two circuits that's about 50V, even if you run them half parallel, half serial per circuit (which usually isn't recommended, or at least I don't) you are above 24V. My point is, the PSU will be determined by the LED setup you end up with.

I just find it hard sifting through all of this info, most of which I don't understand.

One of the reasons I think a reef central WIKI will make everyone's life easier...

Also, if there has been a dimmer module designed for the drivers, Id appreciate the docs on that too...if you don't mind sharing. I will be having the boards redesigned for my needs (space etc). If that is alright too. I would obviously credit you for the initial design

Both the CAT4101 and LM3409 designs take standard 5V PWM for dimming or you can put a potentiometer on either to do it manually. Nothing special is needed, since you mentioned you have an arduino.

As I understand it goes power supply to dimmer module, dimmer module to controller and drivers, drivers to LED boards.

I don't know if this will come out right but I'll try:

Power supply - Driver - LEDS
                        |
            controller(acting as dimmer)



Good luck

 

[reefocean]

Unfortunately it isn't that easy. 32 LEDs with avg 3Vfw is almost 100V. In two circuits that's about 50V, even if you run them half parallel, half serial per circuit (which usually isn't recommended, or at least I don't) you are above 24V. My point is, the PSU will be determined by the LED setup you end up with.

Yeah, figured that much, wishful thinking. The basics I understand, Voltage is shared per circuit, current is split per circuit and wattage is share for all combined circuits. I guess it wouldn't matter is using more drivers, since they are quite cheap. How many channels or drivers can a DIY driver typically run, using Arduino of course? I can understand it all the way down to the driver chip, but then I am lost hehe. But I am learning.

Both the CAT4101 and LM3409 designs take standard 5V PWM for dimming or you can put a potentiometer on either to do it manually. Nothing special is needed, since you mentioned you have an arduino.

[/quote]

Okay, it is sinking in.

So what design do you think would suit my need better? Your latest build or DWZM's initial build? I have already book marked his files

One of the reasons I am trying to learn, is the designer charges per hour, I have about 3k put aside for this and after I have the heat sinks prototyped, purchase the LEDs etc there isn't much left for board design. Plus with the direction I am going, I should really know this stuff. The engineer I have lined up is competent and experienced PCB and design and LED arrays. I am also learning a lot. That is why Id prefer a rough model to offer him, to cut down on expenses. This thread is helping infinity. Thanks a lot for your response, it helps me a lot.

 

[terahz]

Yeah, figured that much, wishful thinking. The basics I understand, Voltage is shared per circuit, current is split per circuit and wattage is share for all combined circuits.

Again, this depends on the setup, parallel or series strings and what combination of both. You can have all your LEDs on 24V psu, heck you can have them on a 5V psu, but you'll need to provide a lot of current, the other way is also true.

How many channels or drivers can a DIY driver typically run, using Arduino of course?

The popular CAT4101 board is 3 chips on 1 PWM channel. That can power about 18 3W LEDs. I've been running 2 boards with 2 chips each for the two colors of LEDs I have (so 4 boards with 2 chips each). Each board can have its own dimming, so if you have all 3 chips on one board connected to 18 LEDs total, you can dim the 18 LEDs with 1 arduino pin. You can also just wire all boards of one color to one PWM channel on the arduino, or even all boards to 1 channel. A typical arduino has 6 pwm pins.

The LM3409HV board, on the other hand, can be configured from as little as 1 LED to probably 24 LEDs on one chip. Dimming is per chip (at least on the board I'm changing to).

So what design do you think would suit my need better? Your latest build or DWZM's initial build? I have already book marked his files

At this point, I'd say there isn't really better, but what you prefer. The CAT4101 is certainly very simple to implement. Especially compared to the LM3409. Much less components, decent size IC (unlike the tiiiiiiny lm3409). But it tends to heat up unless you dial the voltage close to what the LEDs need. However, since you mentioned you want to run at higher than 1A, I'd suggest something other than the CATs (even though few posts up O2Surplus said it's not a problem to run them in parallel).

One of the reasons I am trying to learn, is the designer charges per hour.

Then start from the beginning of the thread again, and don't skim it this time . Whenever you read something that you don't understand, google it until you do. When you make it to the last post, you'll have a ton on knowledge and 3K to spend on materials and corals, instead of labor. It might help if you read a little bit about basic electronics as well. allaboutcircuits.com is not a bad place for that. If you really want to start properly go through the MIT EE circuits and electronics video lectures, it will help a lot.

Good luck!

 

[firechild]

I've read about 40 pages of this thread and can't find any DIY drivers that will run 12 emitters in series. Have I missed them or has noone actually made one. My issue is that I have custom MCPCBs that have 12 blue/royal blue emitters in series as well as 6 cool/neutral whites. I could use these DIY drivers to run the whites but not the blues. Ideally I want to use 1-10v analogue dimming because I have a controller that uses this but if I had to, PWM could work, I would just have to buy a new controller.

 

[terahz]

The last 5-6 pages hold the answer . Or even just the previous post "The LM3409HV board, on the other hand, can be configured from as little as 1 LED to probably 24 LEDs on one chip."

 

[firechild]

Sorry, I hadn't looked through the thread for a few days. I like your design. What would be required to change the analogue dimming signal from 0-5V to 0-10V? Or is that not possible?

 

[der_wille_zur_macht]

Reeefocean, i would not suggest using the original design from this thread. It is limited in its dimming range and some people had downright poor stability from it.

I am struggling to understand what you are paying an engineer by the hour to do when pretty much any DIY LED driving problem has been or can be solved for free in this thread.

 

[der_wille_zur_macht]

Firechild, what need do you have for a 10v dimming signal?

 

[terahz]

Sorry, I hadn't looked through the thread for a few days. I like your design. What would be required to change the analogue dimming signal from 0-5V to 0-10V? Or is that not possible?

Change the voltage divider (R6) to make 10V -> 1.24V (Something like 212KOhms). You will also either have to find a different opamp that works with 10V supply, or put a couple of same value resistors (say 212KOhm, if that's what you use on the first divider) on the 5V input (one in series with the 10V source, another in series with ground) to bring it down to ~5V. That should do it.

 

[der_wille_zur_macht]

I am fiddling with the BOM for terahz's design to give 5A current at roughly 28 Vin (the highest the typical adjustable 24v DC supply will go). Using parallel strings of 7-8 LEDs this nets a roughly 130w driver, for maybe $30-40 including the DC supply. Consider that an Inventronics 120w driver runs around $100.

 

[kcress]

I am fiddling with the BOM for terahz's design to give 5A current at roughly 28 Vin (the highest the typical adjustable 24v DC supply will go). Using parallel strings of 7-8 LEDs this nets a roughly 130w driver, for maybe $30-40 including the DC supply. Consider that an Inventronics 120w driver runs around $100.

....Include a fan in the design and think about the air flow.

 

[snorkeler]

I am mainly browsing the forums from a smartphone these days so finding info in these big threads is awkward at best.

Off topic, but, you need to try Tapatalk on your smartphone! It is so ergonomic on a smartphone... much much better than trying to read the forums through the browser!

Snorkeler

Sent from Tapatalk

 

[firechild]

Firechild, what need do you have for a 10v dimming signal?

DWZM,

I'm using one of these dimming controllers. I have played with it a bit using a Meanwell ELN driver and I would prefer to be able to use this rather than replace it which will just add to my mounting costs as I have replaced just about every component I originally bought, from drivers to heatsinks and emitters.

 

[kcress]

Off topic, but, you need to try Tapatalk on your smartphone! It is so ergonomic on a smartphone... much much better than trying to read the forums through the browser!

Snorkeler

Sent from Tapatalk

Except then we'd probably see even more of that incredibly obnoxious advertisement!

Sent from Tapatalk
:rolleye1::rolleye1::rolleye1::rolleye1::rolleye1::rolleye1:

 

[ghellin]

LOL!


Sent from my brain via telepathy.

 

[Gorgok]

Maybe they could add tapatalk to the swear filter to come out as something funny... Even better come up with many and add them as a random replacement so you never know what you will get.

Anyways, i'm waiting for a shipment from China. Had a little help from a pretengineer who said it all looks good, so hopefully it will be so (never know with those pretengineers). Cat4101s, 5 drivers per 'board,' 2 'boards' per board, 10 boards per order, cheap. The pretengineer asked how much light would that put out if they were all hooked up... i really had no good answer.

 

[der_wille_zur_macht]

....Include a fan in the design and think about the air flow.

Why so? The design is within limits for the IC and all components will be within their ratings.

PS- i am asking this question honestly as i am definitely a learner here.

PPS - I refuse to pay money for phone apps in general, but especially when they then force adds on me, and even moreso when they force adds on everyone I communicate with! I was on the Beta for tappatalk back in the day, from a different phone, and at the time it struck me as clunky. I like the browser on this phone, anyways. The real constraints are just input speed, which no app is gonna fix.

 

[snorkeler]

You can customize or even remove the Sent from ad line.

Data entry on a phone, or, pasting referenced URLs, images, etc, is cumbersome, I agree with DZWM.

On topic, would you have an idea, in terms of efficiency, how do these two driver designs compare to the simple driver you posted kcress?

Snork

Sent from my phone, isn't mobile technology wonderful?

 

[der_wille_zur_macht]

In theory the switching supply will be at worst the same as with the other options. With the resistor method and the 4101, efficieny is effectively dictated by the difference in Vin and Vout. With the 3409, efficiency will be at worst that same amount.

The datasheet for the 3409 has info on estimating efficiency and has graphs showing it for certain conditions, if you want more info. The resistor and the 4101 are both linear but the 4101 requires a minimum half volt drop, so the max efficiency is basically dictated by that.