DIY LED controller

[BobCajun]

Reading more about the pulsed light, I can see that it's not going to work the way I thought. You have to have equal total light, meaning it would have to measure at the same intensity as the continuous light. To do that it would have to be more wattage during the pulses. But look at it this way, if you were planning on dimming your lights anyway then you might as well use the pulse lengths and duty cycles that produce best results from the light you have, rather than random ones or whatever ones are produced by a potentiometer.

Whether dimming will actually make it more efficient, as some here suggest that it does, I'm not so sure. I wouldn't think, because the LEDs are at full power during the pulses, just that they're off half the time or whatever the duty ratio is. How could that make it more efficient? Pretty sure you'd have to get a driver that puts out lower current when on full.

 

[BobCajun]

good thread keep it up! building out a Mega to control my room's at the moment.

Anyone is free to post they're Arduino work here if they want. The dimmer was the only thing I was going to make, and that's pretty simple stuff. Actually, I'm surprised that there wasn't already an Arduino thread on the LED forum.

 

[BobCajun]

The thing about the pulsed light, it has to be the same total amount of light but you would be getting about 50% increase in yield. So if that actually proves to be true with Cannabis, you would only need 2/3 as much light to get the same yield. Too bad nobody ever tried pulsed light experiments with Cannabis before.

 

[guod]

just to say,
the 3in1 dimmable driver from Meanwell don´t pulse the output current .
you have to use the LDD-Drivers for this.

 

[FranJan]

http://www.mouser.com/new/meanwell/meanwelllddled/

 

[BobCajun]

just to say,
the 3in1 dimmable driver from Meanwell don´t pulse the output current .
you have to use the LDD-Drivers for this.

What do you mean? One of the 3 in 1s is PWM, is it not? Well that's what PWM is, Pulse Width Modulation.

 

[Greengenes707]

What do you mean? One of the 3 in 1s is PWM, is it not? Well that's what PWM is, Pulse Width Modulation.

PWM signal...not PWM dimming.
Uses a PWM signal to dim the constant current and the actual current is decreased.
Real PWM basically turns on and off fast enough that there is less cumulative light. Seeming dimmer.

 

[BobCajun]

PWM signal...not PWM dimming.
Uses a PWM signal to dim the constant current and the actual current is decreased.
Real PWM basically turns on and off fast enough that there is less cumulative light. Seeming dimmer.

Okay, is there some kind of reference that explains that? I hadn't heard of LED drivers that were dimmed by adjusting the current output based on a PWM signal. Where did you get your information? Is this in reference to regular large size drivers or little chip type drivers?

 

[guod]

i have to correct myself...
there are some 3in1 dimmable driver from meanwell with PWM style output. The PWM XXX constant völtage drivers.

 

[BobCajun]

i have to correct myself...
there are some 3in1 dimmable driver from meanwell with PWM style output. The PWM XXX constant völtage drivers.
View attachment 3635906

So that one can have pulse cycles of 100 Hz to 3 kHz. Somebody said some Meanwells have a limit around 1 kHz. 3 certainly gives you more leeway in the pulse timing, you can use shorter pulses.

 

[BobCajun]

Just some information about dimming;

Drivers with dimming capability can dim the LED light output over the full range from 100% to 0%. Dimming drivers can dim LEDs by reduction in the forward current, pulse width modulation (PWM) via digital control, or more sophisticated methods. Most dimming drivers operate using the PWM method. With this method, the frequency could range from a hundred modulations per second to as high as hundreds of thousands of modulations per second, so that the LED appears to be continuously lighted without flicker.

A benefit of the PWM method is that it enables dimming with minimal color shift in the LED output. According to the Lighting Research Center, dimming causes LEDs to experience a similar shift in spectral power distribution as an incandescent lamp. However, if colored LEDs in an array are used to produce white light, the amount of shift, particularly with red and yellow LEDs, may produce an undesirable effect on the white light that is produced by the system.

Dimming does not result in a loss of efficiency. During dimming, the LEDs are still operated at the same voltage and current as during full light output. In addition, lamp life is not affected by dimming, as is sometimes the case with frequently dimmed fluorescent lighting. Rather, dimming LEDs may lengthen the useful life of LEDs, because dimming can reduce operating temperatures inside the light source. page

So that's why the constant current drivers are not dimmed by changing the current. It would effect the spectrum. That's why the pulse type dimming is used. It's either on full or it's off. It would be nice if you could dim them by current reduction, since it would increase actual efficiency, but I don't think it's available and no telling how it would effect the spectrum.

edit: After I wrote that I found this, which seems conflicting;

What is PWM Dimming?
There are two types of PWM dimming. One works by turning the power to the LED on and off at a fast rate. The on/off rate has to be high enough so that the flicker is undetectable by the human eye. One advantage of this dimming method is that changes in the colour temperature are unnoticeable at different brightness levels. This makes it ideal for architectural lighting projects, where colour stability is a must. The other type of PWM dimming works by controlling the output current of the power supply in a smooth manner. The advantage of this type of dimming is it does not cause any RF interference. Mean Well power supplies use this method of dimming. pdf

So now I'm confused. How is it current variation and pulse width modulation at the same time? Is it flickering on and off or is it smoothly varying the current? Can't see how it could be both. If it's pulsing, as would be suggests by the name PWM, then why would the current be changing? It would seem pretty pointless. Somebody with a potentiometer could stick a current meter on there and see if it really does change.

 

[welight]

Just some information about dimming;


So that's why the constant current drivers are not dimmed by changing the current. It would effect the spectrum. That's why the pulse type dimming is used. It's either on full or it's off. It would be nice if you could dim them by current reduction, since it would increase actual efficiency, but I don't think it's available and no telling how it would effect the spectrum.

edit: After I wrote that I found this, which seems conflicting;


So now I'm confused. How is current variation and pulse width modulation at the same time? That pdf may be full of it, I guess. I haven't heard of that before.

I would not get hung up on this. PWM Pulse width modulation, square wave, time based as opposed to analog dimming, sine wave, thats the basics, both affect current output, analog winds it, PWM chops it, key difference here I believe is analog shifts colour temp, PWM does not, typically PWM is going to be more expensive PS+dimmer than analog+pot but will give you greater control of dimming steps, if you need it, my sense here is most use dimming to be able to work the crop under less than blinding light, but I might be wrong
Cheers
Mark

 

[BobCajun]

I would not get hung up on this. PWM Pulse width modulation, square wave, time based as opposed to analog dimming, sine wave, thats the basics, both affect current output, analog winds it, PWM chops it, key difference here I believe is analog shifts colour temp, PWM does not, typically PWM is going to be more expensive PS+dimmer than analog+pot but will give you greater control of dimming steps, if you need it, my sense here is most use dimming to be able to work the crop under less than blinding light, but I might be wrong
Cheers
Mark

Thanks.

 

[guod]

BASICs
Dimming LEDs via PWM and CCR
http://www.lutron.com/TechnicalDocumentLibrary/048360a_PWM_vs_CCR_LED_App_Note.pdf

Color-shift

PC White = phosphor coated LED = COB

the white point for PWM dimming is constant.
for analog dimming the white point changes but only at extrem values it will leave the 3 step MacAdam Elipse
extrem values means you have to change the current by factor >30 (350 to 10.5mA)

BTW. a color shift within the 3 step MacAdam Elipse can not be recognize by the naked eye

 

[guod]

this is similar to that what meanwell does for 3in 1 dimming, filtering the PWM signal.
https://arduino-info.wikispaces.com/Analog-Output

 

[SSGrower]

For @Greengenes707 question about powering sown of the arduino at night ...

Thinking totally outside the box on this as I do nit yet have an arduino but based on my understanding of arduinos seems that you could trick it to think the day is whatever length you want it to be. So you'll upload a program based on photoperiod the big problem with this as I see it is during photo period shift.

I'm eventually gonna take full advantage of this thread but forgive me if I stay on the sidelines for a bit.

 

[BobCajun]

For @Greengenes707 question about powering sown of the arduino at night ...

Thinking totally outside the box on this as I do nit yet have an arduino but based on my understanding of arduinos seems that you could trick it to think the day is whatever length you want it to be. So you'll upload a program based on photoperiod the big problem with this as I see it is during photo period shift.

I'm eventually gonna take full advantage of this thread but forgive me if I stay on the sidelines for a bit.

If you want to talk to Greengenes you should use his thread. He doesn't follow this one. He also doesn't know any more about them than I do, which is minimal. Your best bet is the actual Arduino forums on their site.