DIY leds Discussion Thread for all your how tos and doubts and anything related

[Neferhotep]

Everything warmer than 0 K radiates.
And HPS at 900 K radiates different wavelengths than LED at 370 K.
But for plants my guess is that air temperature is more important.

 

[Rocket Soul]

Radiant heat is a type of infra red as far as i know. Or better yet, heat radiates thru infrared radiation.
From what i understand the bioactive part of infra red (its more than a thousand nm wide in spectrum) is the parts closest to par, NIR: near infrared, which seems to have some specific effects. While the more long infrared is more just heating the leaves.

If you want to maximize IR on the leaves you should have a heat sink with maximum surface towards the tops, a sheet basicly.

 

[Ttystikk]

my old lights were between 49.77 watts per sq ft all 5000k to 53 watts per sq ft with 2700k and incandescent.

the four i just built have 64 bulbs on 6" centers for 44.24 watts per sq ft with 5000k to 48.59 with 2700k and incandescent. with the 5000k bulbs i get 1200 umols at 12" dead center but pretty even all the way across. i will have close-range reflectors on the sides of the lights to bring up the readings around the edges.

an interesting thing to note is that in my last grow with all leds and no incandescent when i changed out the bulbs from 5000k to 2700k i lost 50 umols at the same height.

here are a couple of pics of the difference in color temp i got in the middle of changing the lights over from 5000k to 2700k.

Are you using supplemental CO2?

That's a lot of wattage of LED lights! It's between 10-20% more than most LED makers recommend for their fixtures.

Again, if it works that's what matters.

How are you removing the excess heat from the grow?

 

[Ttystikk]

Everything warmer than 0 K radiates.
And HPS at 900 K radiates different wavelengths than LED at 370 K.
But for plants my guess is that air temperature is more important.

Not sure where you're getting your numbers but even double ended HPS lights only run at 650 Fahrenheit/616 Kelvin.

That's a similar temperature as an oven on its cleaning cycle or a hot pizza oven.

 

[Ttystikk]

Radiant heat is a type of infra red as far as i know. Or better yet, heat radiates thru infrared radiation.
From what i understand the bioactive part of infra red (its more than a thousand nm wide in spectrum) is the parts closest to par, NIR: near infrared, which seems to have some specific effects. While the more long infrared is more just heating the leaves.

If you want to maximize IR on the leaves you should have a heat sink with maximum surface towards the tops, a sheet basicly.

Yes. But how much near infrared is desirable, as opposed to just plain old warm surface to heat the air?

 

[Neferhotep]

Not sure where you're getting your numbers

Then why don't you tell where you get your numbers?

My 900 K was a guess.
However, I found some information here.

the high pressure sodium vapor discharge arc operates at temperatures of up to 1500 C

So that would be up to 1770 K rounded, twice as much as my guess

 

[Rocket Soul]

Yes. But how much near infrared is desirable, as opposed to just plain old warm surface to heat the air?

The metal surface is both heating the air thru convection, and then throwing some radiant heat, all depending on how hot it is. Id say infra red is more effective for heating the leaves so it all depends on the situation.

 

[Neferhotep]

how much near infrared is desirable

Not much because it will make the plants stretch.

throwing some radiant heat

Are you still talking LEDs? You'll have to thermally isolate the topside. The little IR will have to radiate downwards.

 

[Ttystikk]

Then why don't you tell where you get your numbers?

My 900 K was a guess.
However, I found some information here.

So that would be up to 1770 K rounded, twice as much as my guess

That's the element itself. The lamp, more specifically the envelope of the lamp, is designed to operate at about 650F/615K. That's the double ended HPS, the single ended didn't run as warm and apparently suffered somewhat in efficiency because of it.

Such lamps operate at about 40% initial efficiency of they're driven by a digital ballast, either high frequency or digital square wave types. Lamps running on magnetic ballasts are about 30% efficient.

My numbers come from Philips Corp white papers on their lamps.

Modern LED lighting is indeed a big step up.

 

[Ttystikk]

Not much because it will make the plants stretch.

For those of us growing on vertical trellis panels, a bit of stretch is fine and desirable. Later in the bloom cycle they're not stretching anyway.

 

[Ca++]

Radiant heat is a type of infra red as far as i know. Or better yet, heat radiates thru infrared radiation.
From what i understand the bioactive part of infra red (its more than a thousand nm wide in spectrum) is the parts closest to par, NIR: near infrared, which seems to have some specific effects. While the more long infrared is more just heating the leaves.

If you want to maximize IR on the leaves you should have a heat sink with maximum surface towards the tops, a sheet basicly.

Yes, it's near ir that we see as plant lighting, and far that's plant heating.

 

[Ca++]

all infrared heat is radiant heat but not all radiant heat is infrared heat.

What radiant heat isn't IR.
You mean light can warm, to a lesser degree. Shown by the thermometers above
Fair comment, as is anything above absolute very being a radiator. It depends where you draw the line. The image is concerned only with radiant heating, which is why it's so centered in the far IR. Where it is just radiant heat.

I have been pointing my remote at my slippers long enough to say it don't work

 

[jonesfam7715]

Got a bunch of osram 850nm and 930nm stars been wanting to try out. Don't really have much faith in effect, but I will try regaurdless probably gonna stretch the plants into the light.

 

[Ca++]

Got a bunch of osram 850nm and 930nm stars been wanting to try out. Don't really have much faith in effect, but I will try regaurdless probably gonna stretch the plants into the light.

Timing is everything. I wouldn't like to guess what will happen though. I have not seen 930 in studies, and 730 seems the common choice for trying to get a reaction. 850 and 930 sound like something for after lights out. Though I think that horse has been flogged to death.

You might nail in down down. The incandescent approach is simply more of everything, and shows there is something. Commercial research doesn't seem to of spotted it yet, but there are other plants that look to warmer coloured light as a hurry indicator. I think it's heat though. Bud temps specifically. Any radiant source seems to be interesting. Without the heat from HIDs many found LED a problem. We probably all saw it. No reading papers required

 

[greyfader]

Are you using supplemental CO2?

That's a lot of wattage of LED lights! It's between 10-20% more than most LED makers recommend for their fixtures.

Again, if it works that's what matters.

How are you removing the excess heat from the grow?

no co2 in a leaky old farmhouse i was renting while i built my new house. there were so many drafts it would have been wasted. but it maintained ambient co2 no problem.

the air leaks helped dump excess heat too. this was in a bedroom so during lights on i had the door open with a big fan blowing floor level air into the room.

only two big plants. and about 2000 watts average.

 

[greyfader]

What radiant heat isn't IR.
You mean light can warm, to a lesser degree. Shown by the thermometers above
Fair comment, as is anything above absolute very being a radiator. It depends where you draw the line. The image is concerned only with radiant heating, which is why it's so centered in the far IR. Where it is just radiant heat.

I have been pointing my remote at my slippers long enough to say it don't work

taken from wiki;

"while infrared radiation is often associated with heat, "heat" itself is not synonymous with infrared; any form of electromagnetic radiation can transfer heat if absorbed by an object, meaning heat can exist outside the infrared spectrum, including visible light and even higher energy radiation like ultraviolet rays at very high temperatures.

Key points to remember:

• Thermal radiation:
  This term refers to any electromagnetic radiation emitted due to an object's temperature, and it can include wavelengths beyond infrared, like visible light from a hot object.
  
  
• Infrared radiation:
  This is a specific band within the electromagnetic spectrum, often associated with heat because many objects at typical temperatures emit most of their thermal radiation in this range."

 

[jonesfam7715]

Even when the "science " tells us things won't work I believe it is important to try things out for ourselves, especially when the Data is recorded by a person or company that benefit from the results. Manipulation and bias opinions, highlighting only pros or cons just to prove a point or set their product above the rest, marketing schemes IMO.

 

[Neferhotep]

The lamp, more specifically the envelope of the lamp, is designed to operate at about 650F/615K.

You are right but the tube is the main source of the infrared.

As for the 850 and 930 nm LEDs, those are frequencys we can't see so it's interesting how you would know how much "light" is shining? But I guess the wattage of the drivers is some measure.

 

[jonesfam7715]

That doesn't matter. The tube is the main source of the infrared and that's what we're discussing.

As for the 850 and 930 nm LEDs, those are frequencys we can't see so it's interesting how you would know how much "light" is shining? But I guess the wattage of the drivers is some measure.

Just gonna check the current These IR diodes are 1.5 volt but like most all other high power diodes 350ma typical

They're only like .06 - .08 each on arrow, prolly cuz Noone wants 850nm or 930nm diodes for anything, been sitting on the shelf to long

 

[Aristoned]

Just gonna check the current These IR diodes are 1.5 volt but like most all other high power diodes 350ma typical
View attachment 19165959 View attachment 19165960
They're only like .06 - .08 each on arrow, prolly cuz Noone wants 850nm or 930nm diodes for anything, been sitting on the shelf to long

I like the idea of IR instead of radiant heat.

If these can achieve high enough leaf temps then I can remove my heater.

Please, let me know how this goes.