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

R_Mc said:
And what of the animals observing the aquarium. Photosensitive epilepsy generally occurs at frequencies between 7 and 30hz. The higher frequency flickering may not cause significantly noticeable health effects in coral, with rudimentary photo receptors that are designed to sense Flux over time. Eyes and the pvcs of fish and mammals are far more complex and are tuned to quick movements and flashes of light.

Personally, I am sensitive to flickering lights and immediately notice poorly filtered led drivers or ballasts. Similarly, I notice the flickering of the dimmed Meanwell and find the light of a poor aesthetic quality. The light agitates me and I can only imagine that it does the same for some of the life in my tank.

Its possible that a higher frequency could help, but the Meanwell seems limited to 1khz. Are there drivers out there that can deal with a higher frequency?

Right now I use an arduino mini pro with the PWM resolution modified to 16 bits. This gives 64,535 values for fading which I find necessary - unfortunately it in turn limits the 16mhz PWM frequency to 240ish hz.

Seems like I'd need at least a 64mhz chip to top out the Meanwell at 16bit resolution.
Click to expand...

I would trade off fading values for a 1000hz frequency, at that speed it would be near impossible to see it with the human eye above 10% duty cycle.

That is where having the right current driver comes into play, if you have them dimmed way low for much of the time use a lower current driver to increase the duty cycle (and overall efficiency of the light), while reducing noticeable flicker.

at 240 hz once you drop down to around 25% duty cycle it becomes possible to see the flicker with the human eye.
 
it seems like the ideal solution would be independent PWM inputs for current output and pwm output control. That way it could be dimmed down to 50% duty cycle or so and then the current could be reduced.
 
R_Mc said:
it seems like the ideal solution would be independent PWM inputs for current output and pwm output control. That way it could be dimmed down to 50% duty cycle or so and then the current could be reduced.
Click to expand...

There are LDD format drivers that do that but the circuitry needed and extra controller functions are going to be beyond what most reefers will ever need. DIYable for sure though.

for example:
http://www.micropowerdirect.com/Pages/Product/Prod LED.html
 
Thanks, I think I'll give these a try.

Thinking that for the smoothest dimming I'd want to

Starting up From off: figure out the minimum turn on current and start the analog dimmer at that point (likely around 10-14%) with the PWM dimmer set to the minimum duty cycle

Then ramp PWM dimming all the way up while holding the analog dimmer at 10-14%

Then ramp Analog dimming up to 100%

The tricky bit would be making it smooth through the transition
 
Cool - though at 12 bits the PWM frequency can be set to 1khz even on the base arduino. The issue comes at 16bits.
 
Krazie4Acans said:
If you power up LDD'd without any LEDs connected you will fry them. Krazie :jester:
Click to expand...

Isn't that what pwm does?

I am making an expandable controller with a couple of extra ldds in case more strings need to be added and was just planning on leaving them connected and powered with no load when not in use, so I guess that would not work?

Also would that mean if a string fails, the ldd would blow too?
 
Got a new issue now. I have a string of 4 led connected to a 600ma LDD, and the string would turn off and on once in awhile. I checked the wiring, and everything looks good. Any ideas?
 
Last edited:
What are the 4 led's? Or specifically, what is their voltage drop at 600ma?

What is the supply voltage to your LDD?

Could be an undervoltage protection / ocp issue.
 
R_Mc said:
What are the 4 led's? Or specifically, what is their voltage drop at 600ma?

What is the supply voltage to your LDD?

Could be an undervoltage protection / ocp issue.
Click to expand...

The 4 LEDs and powersupply used are the following:

(Ledgroupbuy) 2 Exotic Cool Blue 3.6V Fv, max 700mA
(Ledgroupbuy) 2 Exotic Turquoise 3.6V Fv, max 700mA

Supply Voltage is 48V from Meanwell SE-450 powersupply.

For testing purposes it is connected directly to 4 LDD up board with jumper removed.

Thanks
 
Got a question for you gentlemen. My Bluefish controller will not dim any of my LDD below 1%. I've tried it with LDD-1000H, LDD-700H, and LDD-300H, and with various strings of LEDs. I've been talking with the Bluefish dev and he hasn't had anyone else complain about it. :)

He says the Bluefish sends a 580Hz 12-bit PWM signal. Can anyone else with a 12-bit controller (or if you have a Bluefish then use that :)) try and run LDD below 41/4095?
 
blitz49 said:
The 4 LEDs and powersupply used are the following:

(clay-boa) 2 Exotic Cool Blue 3.6V Fv, max 700mA
(clay-boa) 2 Exotic Turquoise 3.6V Fv, max 700mA

Supply Voltage is 48V from Meanwell SE-450 powersupply.

For testing purposes it is connected directly to 4 LDD up board with jumper removed.

Thanks
Click to expand...
check each pad to heat sink for solder bridges..
Could also be a bad driver.. If you have extras solder a string or 3-ish together in "free air" and see if the driver behaves the same.

Check voltage out on ps.

I'd downgrade my ps if you are just using those few.. unless you have other channels.. just not real efficient.

Could be a bad LED too. Test each w/ a VOM

Swap PS w/ a 24V DC 1A wall wart..

Did I miss anything???
 
jedimasterben said:
Got a question for you gentlemen. My Bluefish controller will not dim any of my LDD below 1%. I've tried it with LDD-1000H, LDD-700H, and LDD-300H, and with various strings of LEDs. I've been talking with the Bluefish dev and he hasn't had anyone else complain about it. :)

He says the Bluefish sends a 580Hz 12-bit PWM signal. Can anyone else with a 12-bit controller (or if you have a Bluefish then use that :)) try and run LDD below 41/4095?
Click to expand...

No problems on the Storm X.
 
R_Mc said:
Its possible that a higher frequency could help, but the Meanwell seems limited to 1khz. Are there drivers out there that can deal with a higher frequency?

Right now I use an arduino mini pro with the PWM resolution modified to 16 bits. This gives 64,535 values for fading which I find necessary - unfortunately it in turn limits the 16mhz PWM frequency to 240ish hz.

Seems like I'd need at least a 64mhz chip to top out the Meanwell at 16bit resolution.
Click to expand...

I think you are getting a couple of things mixed together here. the bit resolution/ number of values has nothing to do with the PWM frequency. If the PWM frequency is 1khz then it is 1khz. It's not dependant on the PWM resolution. I have never seen an Arduino with a PWM frequency of 240hz (or ish).

Quoted from Arduino web site: "The frequency of the PWM signal on most pins is approximately 490 Hz. On the Uno and similar boards, pins 5 and 6 have a frequency of approximately 980 Hz. Pins 3 and 11 on the Leonardo also run at 980 Hz."

This would mean that the minimum frequency of the PWM from an Arduino would be 480hz. While the human eye may be able to see 60hz-120hz flicker on a florescent bulb and maybe even 240hz at a 10% or less duty cycle, I find it very hard to believe that the human eye can see 490hz at any duty cycle. Nor would the human eye be able to perceive 980hz at all.

Now if you personally don't like the effect of the light that you see, then that is a personal opinion and I would say "then don't use it". However, if you don't like LEDs at those frequencies then I'm not sure how you could possibly like florescents at all. Krazie :jester:
 
oreo57 said:
check each pad to heat sink for solder bridges..
Could also be a bad driver.. If you have extras solder a string or 3-ish together in "free air" and see if the driver behaves the same.

Check voltage out on ps.

I'd downgrade my ps if you are just using those few.. unless you have other channels.. just not real efficient.

Could be a bad LED too. Test each w/ a VOM

Swap PS w/ a 24V DC 1A wall wart..

Did I miss anything???
Click to expand...

Finally got this issue resolved. Turns out it was one of the LLD holder, causing power to fluctuate. Switched out the 4 up LLD board and everything is working. Thanks guys.
 
Krazie4Acans said:
I think you are getting a couple of things mixed together here. the bit resolution/ number of values has nothing to do with the PWM frequency. If the PWM frequency is 1khz then it is 1khz. It's not dependant on the PWM resolution. I have never seen an Arduino with a PWM frequency of 240hz (or ish).

Quoted from Arduino web site: "The frequency of the PWM signal on most pins is approximately 490 Hz. On the Uno and similar boards, pins 5 and 6 have a frequency of approximately 980 Hz. Pins 3 and 11 on the Leonardo also run at 980 Hz."

This would mean that the minimum frequency of the PWM from an Arduino would be 480hz. While the human eye may be able to see 60hz-120hz flicker on a florescent bulb and maybe even 240hz at a 10% or less duty cycle, I find it very hard to believe that the human eye can see 490hz at any duty cycle. Nor would the human eye be able to perceive 980hz at all.

Now if you personally don't like the effect of the light that you see, then that is a personal opinion and I would say "then don't use it". However, if you don't like LEDs at those frequencies then I'm not sure how you could possibly like florescents at all. Krazie :jester:
Click to expand...
You can easily change the frequency of the PWM on the arduinos. It is also possible to 'persuade' it to do higher resolution dimming as well (O2Surplus does, or at least did, on his vero build) but I'm not sure how as i simply use the PCA9685 chips :)

Tim
 
perkint said:
You can easily change the frequency of the PWM on the arduinos. It is also possible to 'persuade' it to do higher resolution dimming as well (O2Surplus does, or at least did, on his vero build) but I'm not sure how as i simply use the PCA9685 chips :)

Tim
Click to expand...

Agreed there are ways to change it (at least increase the frequency not reduce) but there are other issues with doing that and it probably doesn't work well with Storm or Blue controllers.

Also using the 10bit resolution reduces the PWM output pins from 6 to 4. Again may be fine if you are doing your own controller but it's not going to work with a pre-made controller.

And again the frequency is just the number of times the signal changes state per second. It does not affect the duty cycle of the on/off duration. Nor does the current output effect frequency or duty cycle.

I'm really confused by R_Mc's comment about having a dual dimming driver that does both PWM and current regulated dimming. If the issue is flicker at low duty cycle PWM then his idea would not solve that at all. If you are using PWM to dim at the low end of the dimming then it doesn't matter if the current is 10-15% the flicker is still going to happen. It might be dimmer while it flickers but it's still going to flicker. This is more of an either or thing and really does not suit itself to a combination. If you wanted a driver that had an adjustable current max but was still dimmed viw PWM then that is acceptable but having multiple types of dimming is a bit absurd. Krazie:jester:
 
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