Explain Mean Well LDD's like i'm five...

[Pearson]

I have been reading the thread on the meanwell LDD's and how to dim to zero but it's not setting in. I'm not understanding how to implement them. I have the meanwell eln-60-48d drivers and pots to manually dim them but I think the LDD's will work better (less space, easier to hide, cheaper).

Here's what I have:
2 heatsinks with
24 XP-G RB
24 XT-E CW
8 XP-E Green
8 UV (from Rapidled)
6 ELN-60-48D
3 10K POTs

since they are on 2 heatsinks, half of the LEDs will be on one and half on the other. I don't really want wires going across the heat sinks so i'd need drivers for 4 green and 4 UV. That may be a discussion later.

On to the questions:
How do you chose the right LDD? They come in 300-1000.
What specs are you looking at to figure out which LDD to get?
The LDD's don't have a power supply, right?
How do you know which psu will work?
What specs are you looking at to figure the correct psu?
How do you get the LDD's to dim? A controller or will POTs work?
Since the units are smaller, would it be better to have 1 driver for all LEDs or 2 per half the LEDs? (1 driver for all 8 green {with wiring going across both heatsinks} or 2 drivers for half{1 driver for 4 green on each heatsink})

Break it down like i'm five. I want to understand this but nothing in the threads i've read are sinking in. It seems like it's pretty easy, and I think I understand it, but whenever I look into buying the LDD's I can't remember which ones i'm supposed to get. Sorry for the multitude of questions but DIY LEDs are rather difficult for some reason.

 

[nemosworld]

step 1:
look at the max current for each led type that you want to use, for instance the xte has a max current of 1500ma, however the largest ldd is 1000ma, so go with that.
any led that has a max current of 700ma you can go with a ldd-700 series or a 500.

step two:
look at the forward voltage of each led type, for this example again the xte has a max forward voltage of 3.4, the ldd has a max vf of 52, if you divide 52 by 3.4 you will get just a little over 15 leds, however you won't find a power supply with 52v so 48v will be the choice. now 48v divided by 3.4 will give you 14 leds. so a Ldd-1000h running 14 cree xt-e series will need a power supply with 48v.

step 3: for every 1000h you use you will need 1amp on your power supply
1000ma equal 1amp so if you had 2 700h you would need 2amps.

step 4: wattage
count the total wattage of your leds, this will give you the wattage needed from the power supply.

step 5: head room
give yourself some headroom for everything on the power supply:
5 ldd 1000h should have a 6 amp power supply
if your leds on a string equals to 48v or more, you need to remove 1-2 until you total 46-47v or right at 48v.

hope this was explained easy enough.

 

[sfsuphysics]

How do you chose the right LDD? They come in 300-1000.
The number dictates the max number of milliamps they will output.

What specs are you looking at to figure out which LDD to get?
If you want wires to connect everything to, get the LDD with the HW suffix, i.e. LDD-1000HW, if you want those with pins that you either solder your own wires to or attach to a premade board (see other thread) then get the one with the H suffix LDD-1000H. Deciding the "number" to choose, decide what the max current your LED can handle and go with that, for instance many (all?) UV and red LEDs have a maximum current of 750mA, don't get anything more than that for your driver.

The LDD's don't have a power supply, right?
Correct, the LDDs simply do all the magic to turn a DC signal into a constant current DC signal

How do you know which psu will work?
Any PSU with a DC output would work. The only requirements of the PSU is that it has the enough voltage to handle your LED strings plus 3-4 volts of overhead that the LDD uses to make the magic happen. As well as the total power output.

What specs are you looking at to figure the correct psu?
Really depends how long your strings are, most people try to max out their string length of 12-13 LEDs per string (i.e. per LDD), so in that case you'll want a PSU that outputs 48 volts. Add up the power of each LED and the total power output of your PSU needs to be that, don't worry about current rating of the PSU because the LDD will do all the magic to get what current it needs out of it. Just going by a very rough estimate of 3 watts per LED, that adds up to 192 watts. So you'll probably want a PSU that has at least 200 watts output, and 48 volts of DC power.

How do you get the LDD's to dim? A controller or will POTs work?
LDDs don't dim via pots, on your ELN drivers the pots simply change the voltage on the dimming signal that goes into the ELN driver, LDDs don't work on this method. They use what's known as Pulse Width Modulation or PWM, you need a controller that can do this. Ardino based controllers can do this, for instance I bought a Typhon LED controller, that does all the dimming I need.

Since the units are smaller, would it be better to have 1 driver for all LEDs or 2 per half the LEDs? (1 driver for all 8 green {with wiring going across both heatsinks} or 2 drivers for half{1 driver for 4 green on each heatsink})
You're still going to be limited to the number of LEDs per driver, LDD drivers are great but they're not that good to drive all of that. The RB and CW LEDs you'll want to split those up into 2 groups of 12 LEDs each, and then use the 1000mA versions of LDD. The UV and green should each be on their own drivers, the UV should be on a LDD700 since they max out at 750mA, I'm not sure what the max on the green is, but I'd probably put that on 700 as well since you probably don't want to run those at full power anyways even if they could handle it. Now if you had something like the Typhon mentioned earlier, it has 4 different channels it can control, and for your setup of blue, white, green and UV you're good to go (you can tie multiple LDD drivers to a single channel).

Now as far as PSU, you're not going to be using any more than 200 watts, so a single PSU is probably best. If you were dealing with a lot higher power requirements, it becomes more beneficial to split up multiple PSUs, but for you this shouldn't be a case.

Hope that was 5 year old enough

 

[Pearson]

hope this was explained easy enough.

Thanks. I think I understand it.

Hope that was 5 year old enough

Thanks for that. :lol: I think that was exactly what I needed. Couple more questions though.

So, a parts list that I am looking at:
4 LDD-1000H (2 for the RB/ 2 for the CW)
4 LDD-750H (2 for Green/ 2 for UV)
250w 48v PSU
Typhoon Controller (1 channel for each RB/CW/Green/UV)

This will be all that I need?

Mounting the LDD's, what are the ways people are doing this?
I would probably put all the electronics in a project box (bigger than Radioshack carries) so they may be 3-10ft away. Is that an issue?
I seen that 02Surplus built a board, what is that for? The LDD's mount to it but i'm not sure how it connects to the LEDs or PSU.

I appreciate the two of you

 

[asid61]

A 250w won't suffice. You will be drawing 6.8 amps at least from it.
You need 2 250w 48v power supplies.
3-10ft should be fine.
Also, you only need 1 LDD-700HW for the greens, and 1 for the violets. You'll still need two power supplies, but it'll make things cheaper and easier.

Also, consider buying the power supplies from Ebay. Much cheaper than anywhere else. But make sure to go at least 30% higher than what your max led power will be. I.E. if you use 6.8 amps, get a 10a power supply or two 5a power supplies.

 

[Pearson]

A 250w won't suffice. You will be drawing 6.8 amps at least from it.
You need 2 250w 48v power supplies.
3-10ft should be fine.
Also, you only need 1 LDD-700HW for the greens, and 1 for the violets. You'll still need two power supplies, but it'll make things cheaper and easier.

Also, consider buying the power supplies from Ebay. Much cheaper than anywhere else. But make sure to go at least 30% higher than what your max led power will be. I.E. if you use 6.8 amps, get a 10a power supply or two 5a power supplies.

Why won't a 250w work? If there's a 240W 48V 10A driver, wouldn't that work?

What's the math that i'm looking at when picking out the psu?

According to above, i'm looking at roughly:
192w so psu should be 200+w
6.8a so psu should be 10+a
52v so psu should be 52+ or 48 and remove some of the LEDs

Does that seem right?

 

[asid61]

no, no, the psu can be 48v. But the amperage rating should be higher than what you need, as you are buying it from ebay.

Also, a psu wattage is equal to amps x volts. So a 48v 5.2a psu is 249.6 watts.

 

[Pearson]

Check my math, please

24 XT-E RB 1500mA max
24 XP-G CW 1500mA max
8 XP-E Green 1000mA max
8 UV 700mA max

64 LEDs * 3w = 192w
5 LDD-1000 = 5A + 1 LDD-700 = .7A (total = 5.7A)

2 LDD-1000=12 RB 48v/3.4vf = 14 LEDs per string
2 LDD-1000=12 CW 48v/3.25vf = 14 LEDs per string
1 LDD-1000=8 Green 48v/3.9vf=12 LEDs per string
1 LDD-700=8 UV 48v/3.5vf=13 LEDs per string

So for a PSU i'm looking for something with the minimum specs of:
48v 200w 6a
Something like the meanwell SP-320-7.5.

If the meanwell SP-320-7.5 will work, why are there only 3 pos and 3 neg terminals? I need it to run 4 different strings of drivers so I would think there should be at least 4 terminals. I can have the 2 drivers for the RB on the
same terminal so all i'm needing is a terminal for the CW, Green, and UV.

Am I doing this right or am I still missing something?

 

[sfsuphysics]

So, a parts list that I am looking at:
4 LDD-1000H (2 for the RB/ 2 for the CW)
4 LDD-750H (2 for Green/ 2 for UV)
250w 48v PSU
Typhoon Controller (1 channel for each RB/CW/Green/UV)

This will be all that I need?
That should be good, you won't need 2 LDD drivers for your green and UV, and there's no practical advantage to splitting 8 LEDs into two groups of 4. You could, but no reason to do so. Also the LDD-700 is the part they don't make a 750mA version. Lastly you show H and not HW, H is only pins, meant to be put into a circuit board (although you can solder to pins) the HW has wires coming out that you can work with if you're going to go the soldering method anyways.

Mounting the LDD's, what are the ways people are doing this?
They're encapsulated with thermal epoxy IIRC, there's no way you must mount them, I attach them to a piece of aluminum C-channel with a zip-tie if anything just to keep the wires from kinking. Otherway people are mounting them are on those boards from the other LDD thread

I would probably put all the electronics in a project box (bigger than Radioshack carries) so they may be 3-10ft away. Is that an issue?
Should be fine as long as you don't make your wire gauge too small

I seen that 02Surplus built a board, what is that for? The LDD's mount to it but i'm not sure how it connects to the LEDs or PSU.
02Surplus has made quite a few boards, but yeah it's just a "cleaner" way of mounting everything. You would need additional parts so that you can run wires from it to your PSU/LEDs. It's not necessary, but it is a way to reduce the wire octopus look.

The PSU should be fine regardless of current rating. The LDD drivers will convert voltage to current as necessary, they really are magically little boxes. There was some discussion of this in the really long LDD thread, someone even emailed Meanwell to get the answer on this.

If the meanwell SP-320-7.5 will work, why are there only 3 pos and 3 neg terminals? I need it to run 4 different strings of drivers so I would think there should be at least 4 terminals.
Number of terminals is irrelevant. There's a potential difference of 48V from one positive to a neutral, the LDD will see 48V and it'll use whatever voltage it needs to make it run. Seriously these things are electronics black magic in an epoxy covered box.

 

[Eud]

he's right, the three terminals are meaningless. They're all connected together and are just for convenience of wiring. If you need 6 LDD's powered and you don't have boards to mount them to you could always put two on each terminal.

The power supply you are looking at seems fine.

You haven't gone into dimming the LDD's yet. I recommend a Coralux Storm or Storm X to do the 5v PWM dimming instead of DIY. They just look really awesome and much easier and cheaper than any DIY I've seen.

 

[HippieSmell]

Go ask your Mom.

 

[zachts]

on the PSU sizeing note.

with LDDs the amperage doesn't matter. only the total watts being drawn by the LEDs, I calculated something around 183watts using the average specs for the leds he listed. but could go up to 200watts or so depending on exact Vf of each LED.

so all he needs is a 48volt PSU capable of at least 200watts, so the 250watt one would be plenty and give enough overhead for safety.

the LDD driver just for informations sake will take voltage and convert it into drive current which will lower the amperage imput on the green and violet strings since they will only be needing around 28 volts for the leds. that extra 20volts from the PSU gets converted into the current used for the LEDs so the LDD 700s will not be drawing an acutal 0.7amps they will be drawing more like ~0.41amps or so if I did my math correctly.

the LDD 1000s also probably won't draw a full 1 amp either unless the leds are runing a Vf of 4volts, they probably only draw about 0.75amps at full power with the LEDs listed.

 

[asid61]

on the PSU sizeing note.

with LDDs the amperage doesn't matter. only the total watts being drawn by the LEDs, I calculated something around 183watts using the average specs for the leds he listed. but could go up to 200watts or so depending on exact Vf of each LED.

so all he needs is a 48volt PSU capable of at least 200watts, so the 250watt one would be plenty and give enough overhead for safety.

the LDD driver just for informations sake will take voltage and convert it into drive current which will lower the amperage imput on the green and violet strings since they will only be needing around 28 volts for the leds. that extra 20volts from the PSU gets converted into the current used for the LEDs so the LDD 700s will not be drawing an acutal 0.7amps they will be drawing more like ~0.41amps or so if I did my math correctly.

the LDD 1000s also probably won't draw a full 1 amp either unless the leds are runing a Vf of 4volts, they probably only draw about 0.75amps at full power with the LEDs listed.

The amperage DOES matter. While I have heard the LDD take SOME excess voltage and turn it into current, you can't depend on that to supply the extra current you need. The LDD do turn voltage into current, but they don't do it with 100% efficiency.
For example, let's say I'm running 3v of led on a ldd-1000h driver with a 12v power supply. The LDD will not turn the extra 9v into current; rather, it will turn only a little bit. I don't know exactly how much, as I can't find that one forum that documented the phenomenon.

 

[zachts]

The amperage DOES matter. While I have heard the LDD take SOME excess voltage and turn it into current, you can't depend on that to supply the extra current you need. The LDD do turn voltage into current, but they don't do it with 100% efficiency.
For example, let's say I'm running 3v of led on a ldd-1000h driver with a 12v power supply. The LDD will not turn the extra 9v into current; rather, it will turn only a little bit. I don't know exactly how much, as I can't find that one forum that documented the phenomenon.

I'ts in the Meanwell LDD data sheet, there is a curve graph, it acutally turns most of the excess voltage into current, with one 3volt led on a LDD-H running off a 48volt supply the LDD is about 75% efficient. and that is a huge difference in input and output voltage. up where most people are running them with 8-12 LEDs they are in the 85-95% efficient range. this was thoughoulty vetted int massive LDD thread and as long as you plan for 15-20% extra watts in the PSU it will be more than enough. wattage really can be used to size the PSU as long as you have at least around 3 volts of head room above your largest LED string. In the OPs example he has more than enough.

here's the thread, its really long and I don't remember what page this was all figured out on but it was near the beginning of the thread.

http://www.reefcentral.com/forums/showthread.php?t=2222702

The LDD will use some of that extra voltage to do its magic as well, which is why you don't need to foll the amperage based on the LDD rating, rather the LED load, the extra voltage headroom above the output voltage is used by the LDD as well so the total amperage draw remains much lower than you'd expect with other driver types.

It certianly doesn't hurt to use a larger than needed PSU but the extra cost isn't always justified. It's usually better to use two smaller PSUs if in doubt then just one large one.

 

[Pearson]

This will be all that I need?[/b]
That should be good, you won't need 2 LDD drivers for your green and UV, and there's no practical advantage to splitting 8 LEDs into two groups of 4. You could, but no reason to do so. Also the LDD-700 is the part they don't make a 750mA version. Lastly you show H and not HW, H is only pins, meant to be put into a circuit board (although you can solder to pins) the HW has wires coming out that you can work with if you're going to go the soldering method anyways.

I need:
5 LDD-1000 (H or HW) [2 for RB/2 for CW/ 1 for Green]
1 LDD-700 (H or HW) [1 for UV]

That's going to be my 4 channels. From what I was looking at for the boards, from 02Surplus, they have a 6-UP but that seems like it's for controlling 6 channels. The 6-UP would be perfect but I only need 4 channels so I don't understand the wiring.

Mounting the LDD's, what are the ways people are doing this?
They're encapsulated with thermal epoxy IIRC, there's no way you must mount them, I attach them to a piece of aluminum C-channel with a zip-tie if anything just to keep the wires from kinking. Otherway people are mounting them are on those boards from the other LDD thread

The boards seem like a good option but I don't understand how they look with the wiring "finished". Where do the wires get connected? Is there a parts list?

I seen that 02Surplus built a board, what is that for? The LDD's mount to it but i'm not sure how it connects to the LEDs or PSU.
02Surplus has made quite a few boards, but yeah it's just a "cleaner" way of mounting everything. You would need additional parts so that you can run wires from it to your PSU/LEDs. It's not necessary, but it is a way to reduce the wire octopus look.

Question on wiring, if I get the HW series, can I run the wires into a 2 pin connector (1 connector per LDD), then to a 12 pin connector (1 connector for all the LDD's), back to the 2 pin connector, and then have bare wire going to the PSU terminals?

it'll look like this:
1000maLDD---2pin---\ / --4pin to 4pin's (RB) ------ 4pin to bare wire (terminal 2+ and 2-) PSU
1000maLDD---2pin--- \
1000maLDD---2pin--- 12pin
1000maLDD---2pin--- / \ ---4pin to 4pin's (CW)------ 4pin to bare wire (terminal 2+ and 2-) PSU
1000maLDD---2pin--- / \ ---2pin to 2pin (G) ------ 2pin to bare wire (terminal + and -) PSU
700maLDD---2pin--- / \ --2pin to 2pin (UV)------ 2pin to bare wire (terminal + and -) PSU

Hopefully that makes sense. :lol: I don't know if they make connectors that work this way. I believe in unions in plumbing and connectors for electrical work. I was to be able to remove the LDD's individually, incase one fails or I change something. I also would like some connector that will make the bulk of the wiring look beter instead of having 12 2pin connectors and zip tying them all together every 3-6".

 

[nemosworld]

I need:
5 LDD-1000 (H or HW) [2 for RB/2 for CW/ 1 for Green]
1 LDD-700 (H or HW) [1 for UV]

That's going to be my 4 channels. From what I was looking at for the boards, from 02Surplus, they have a 6-UP but that seems like it's for controlling 6 channels. The 6-UP would be perfect but I only need 4 channels so I don't understand the wiring.

You can plug more than one LDD to a controller channel


The boards seem like a good option but I don't understand how they look with the wiring "finished". Where do the wires get connected? Is there a parts list? With each board type posted, there was a parts list included or in a post shortly after. you can also pm the maker of the board to get the parts list.

QUOTE]

 

[zachts]

That's going to be my 4 channels. From what I was looking at for the boards, from 02Surplus, they have a 6-UP but that seems like it's for controlling 6 channels. The 6-UP would be perfect but I only need 4 channels so I don't understand the wiring.

It won't hurt to leave two of the LDD slots on the 6-up board open for future expansion, or as Nemosworld mentioned you could control more than one of the LDDs with one of the controller channels. most arduino based controllers could run a max of 8 LDD's but most people will err on the side of caution and limit it to under 6 LDDs controlled by a single channel.

also while the boards are designed to use screw terminals for connections you can simply solder your wires onto them also. many also use socket connectors to make the LDD removable from the board.

 

[crn005]

Nemosworld, expect to hear from me in the next month or two. I think LDD's will be my next adventure and I remember you mentioning about how you were going to use some on one of your builds.

 

[nemosworld]

Nemosworld, expect to hear from me in the next month or two. I think LDD's will be my next adventure and I remember you mentioning about how you were going to use some on one of your builds.

okie dokie!

 

[gernby]

Sorry for resurrecting an old thread, but I have a couple questions about the LDD drivers that I think you guys could answer. I just finished building a DIY setup using the Meanwell ELN analog drivers, and am now regretting that choice. If I had more time to research, I would have gone with an LDD setup from the beginning. However, it seems that it might not be that difficult to retrofit my setup with LDD's pretty easily.

My questions are:
1) Can I use the ELN drivers that I have now as the power supply for the LDD drivers? Basically, can I just insert the LDD driver right into the circuit between the ELN drivers and LEDs?
2) Can multiple LDD drivers be wired in parallel to deliver more than 1 amp to a string of LED's? For example, if I want to drive LED's at 2 amps, can I wire two 1 amp LDD's in parallel to do it?