Meanwell LDD driver: for those who want to dim to 0 using Arduino

Eud said:
I have a strange problem that I'm having trouble tracing. I have a 48V DC power supply going to the inputs of my Meanwell LDD's and also to a 48V to 12V voltage converter. I use the 12V output to power three fans through a fanspeed adjuster as well as powering two Arduino boards that supply the PWM dimming signal.

I have tied together the DC negative of the Meanwell 48V output, the DC negative of the 12V output, and, by extension, the negatives of the LDD input and Arduino input and fan negatives are tied together.

When I turn on the main power, but keep the Meanwells off (I have the pull-down resistors installed and am supplying 0 duty cycle PWM at that point), I see my red LEDs flickering very dimly. If I turn the fan speed up the flicker goes away.

I've tried measuring continuity around the board and can see that the positive output of the LDD is tied to the positive input, but the negative is not. This is consistent with what others have seen where the current and voltage is adjusted by raising the negative.

Any idea where the red flickering could be coming from? Could it be a consequence of tying the input negatives together instead of the input positives? I know someone has posted on this thread before that it works better if the positives are tied together instead of the negatives.

Any suggestions?
Click to expand...

I have a suspicion that your seeing the side effect of "Inductive Kickback". It's probably happening because the fans. Try installing a small diode in reverse bias across the fan's power and ground wires. That will probably take care of the problem. If not, we'll have to dig a little deeper for a solution.
 
On the Meanwell 48D's I only had 6 LED's and solved the dimly lit issue when off by adding a 10K ohm resistor across the 48D output. I don't know if that will help in this case but if you have fewer LED's on that string it might.
 
O2Surplus said:
I have a suspicion that your seeing the side effect of "Inductive Kickback". It's probably happening because the fans. Try installing a small diode in reverse bias across the fan's power and ground wires. That will probably take care of the problem. If not, we'll have to dig a little deeper for a solution.
Click to expand...

So is that two diodes? One on the power and one on the ground? Or a diode between them oriented so that when power is applied to the fan no current flows through the diode? Sorry to be dense about it. What size diode(s) should I put there?

I was surprised it could light up the reds at all because they should take at least 18V to light and I'm only supplying 12V to the fans. If it makes any difference, this is what I'm using to vary the speed on the three fans:

http://www.newegg.com/Product/Product.aspx?Item=N82E16835118217

n2585722 said:
Does that LED string have fewer LED's than your other strings?
Click to expand...

Yes, it does. It has 9 reds which are only 2V each rather than the 3.2V drop on the blues/whites/etc.

n2585722 said:
On the Meanwell 48D's I only had 6 LED's and solved the dimly lit issue when off by adding a 10K ohm resistor across the 48D output. I don't know if that will help in this case but if you have fewer LED's on that string it might.
Click to expand...

Hmm, like a pull down resistor, what do you think of that one O2Surplus?
 
Cool looking controller you all have going here! I really need to rebuild my 20L's LEDs and ad a controller to them. I have a Typhon but haven't added it to my current light set up yet. Looking over this thread it seems everything is listed in one place or another for all of the components to build one of these myself. But...there is always a but....I haven't done any PCB work in 20 years and am lost at some of it now.
Now on the flip side if there is enough need or interest I can build a custom box to house one of these controllers. I am currently making housings for the Typhon and the DIM4 controllers and could do the same for these as well.


 
I'm very interested in getting some sort of enclosure for the board I designed, but I wouldn't go so far as to call it a controller. It's just a breakout board for the LDD drivers, to clean up the wiring (and add the feature introduced by O2Surplus, where if the control line is disconnected, the LEDs dim to 0%). I've asked Roberto at Reef Angel to put together some custom 16-channel dimming expansions for the Reef Angel controller to run my setup.

W/r/t the breakout board, you shouldn't have to read too far back to find the most recent info for the 6-up boards. Post 1726 includes, as an attachment, the zip file containing everything the PCB house will need to print you some boards. Post 1728 lists the hardware you'll need to mount to the board after printing.
 
aaronpentz said:
Ive also got a favor for the people that can develop circuit boards. I can get pretty much anything you want laser cut I work for an OEM CNC Laser Cutting Machine Manufacturer. I would be willing to trade my services and material for your design capabilities. Id like a custom board designed.
Click to expand...

I had fun designing my 6up board, and wouldn't mind the challenge of designing another. I would also be interested in getting some sort of enclosures for the boards I designed -- just a project box appropriately sized for the board, with room for connectors in and out. Is that something you can help with?
 
Eud said:
Or a diode between them oriented so that when power is applied to the fan no current flows through the diode?
Click to expand...

That is correct - That's what's called a "reversed biased" diode. The diode acts as a path a to ground for any induced voltage that may be remaining in the fans windings after the power is turned off.

Eud said:
Sorry to be dense about it. What size diode(s) should I put there?
Click to expand...

Any small diode should work. There's not enough current in the circuit to make the exact rating a worry.
 
O2Surplus said:
That is correct - That's what's called a "reversed biased" diode. The diode acts as a path a to ground for any induced voltage that may be remaining in the fans windings after the power is turned off.



Any small diode should work. There's not enough current in the circuit to make the exact rating a worry.
Click to expand...

Thanks very much. Will try it tomorrow.

CrazyZoa said:
Cool looking controller you all have going here! I really need to rebuild my 20L's LEDs and ad a controller to them. I have a Typhon but haven't added it to my current light set up yet. Looking over this thread it seems everything is listed in one place or another for all of the components to build one of these myself. But...there is always a but....I haven't done any PCB work in 20 years and am lost at some of it now.
Now on the flip side if there is enough need or interest I can build a custom box to house one of these controllers. I am currently making housings for the Typhon and the DIM4 controllers and could do the same for these as well.


Click to expand...

That looks really nice.
 
O2Surplus said:
That is correct - That's what's called a "reversed biased" diode. The diode acts as a path a to ground for any induced voltage that may be remaining in the fans windings after the power is turned off.

Any small diode should work. There's not enough current in the circuit to make the exact rating a worry.
Click to expand...

I picked up an IN4004, just cause it was the first one in the drawer. So I'll put the end with the band on the red (positive) wire and the other end on the black, right?

That's what I'm gonna do now. Hope I don't let the smoke come out, heh.
 
Eud said:
I picked up an IN4004, just cause it was the first one in the drawer. So I'll put the end with the band on the red (positive) wire and the other end on the black, right?

That's what I'm gonna do now. Hope I don't let the smoke come out, heh.
Click to expand...

You've got 50/50 odds of getting it right or wrong. LoL Yes- point the banded end of the diode towards the positive and you'll be fine. I just hope that installing the diode takes care of your problem. LoL
 
Ordered mine. Getting them really cheap from someone who started the project and didn't have time to finish it.

10 4UP Version1 boards, 6 LDD-1000H Drivers and 400W 48V power supply (meanwell knockoff) tested and working. for $60.

He already started soldering thing up so some of the boards have the screw down terminals on them already.

Excited, they should be here Friday.
 
Sacohen said:
Ordered mine. Getting them really cheap from someone who started the project and didn't have time to finish it.

10 4UP Version1 boards, 6 LDD-1000H Drivers and 400W 48V power supply (meanwell knockoff) tested and working. for $60.

He already started soldering thing up so some of the boards have the screw down terminals on them already.

Excited, they should be here Friday.
Click to expand...


Nice score!
 
Thanks. I may have to get a bigger PS or a 2nd one, I really didn't figure out my LED's yet.

It think this was asked before and the answer was not really, but is there an issue with putting 7ma LEDs on a 1000ma driver?
 
Sacohen said:
Thanks. I may have to get a bigger PS or a 2nd one, I really didn't figure out my LED's yet.

It think this was asked before and the answer was not really, but is there an issue with putting 7ma LEDs on a 1000ma driver?
Click to expand...


7ma Leds ??? There would definitely be "issues"- mostly a brief flash of light followed by a lot of smoke. LOL

I hoping you meant a 700ma led?
 
I did mean 700 ma. Not fully awake yet.
So back to the original question, but with 700 ma LEDs, would they be ok on 1000 ma drivers?
 
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