Okay, and I'm here with everyone knows Doug Ford of Doug Ford analog design and he's got some cool light panels for us cuz he's into everything lighting including uh yeah, everything analog. plus LED lighting and stuff. and you're the acoustic and audio Guru something a bit like that. Awesome.

So yeah. look, we've got some panels. These are four. They're 1200 mm x 300 mm nominal Power 60 WS input nominal output about 3,000 lumens.

so nominal efficacy around about 50 Lumen per watt, 50 L per watt. And unfortunately, that's around about what you can expect from these. uh, diffused flat panel emitters. Yep, the leads inside them are probably 120 Lumen per watt, but by the time you go through the side process and diffusion out, relatively low efficacy, but very good quality of light with low glare.

Excellent. That's exactly what I want. The idea is: put these on the wall in front of me to, uh, light up my face in front of the video cuz the corner of the lab is actually quite dark. So that's the idea.

So these are strip of LEDs down the side, right? So there'll be a flat PCB down the side of that. Yes, we' got four inputs. They've basically segregated the the power to these into four groups. probably because they have four 600 mm Pcbs.

Okay, and there's none on the top and the bottom. It's just, and we can find that out quite readily by powering up one of the four groups. Let's do it. We haven't powered this thing up yet.

so yeah, we have here a a a 3 amp power supply. Yep, we have a controller which is actually an RF controller for dimming and it comes with a little wanky remote control Tada So you can dim them from a distance so we'll put batteries in that later and find out how well it dims. Okay, let's run up. Let's do it.

Hey here we go. We're up. Okay now. depending on how well the video camera shows this, it may not I've got Auto contrast this Auto exposure.

So yep, we can see that let's see split in the middle there. Yes, Now you can tell that uh, despite the fact that we've only got one half of it illuminated, it's uh, diffusion is really very good. The diffusion is very good. It's PR you know? Well, we could get the light meter out and see what the difference is here as it and as it drops going across.

I guess so we could almost get the function of the plastic. If they've got it right, we'll be going from 100% to 50% to 25% over the span there. and it's linear it. It should be uh, linear per unit length which actually makes it logarithmic when you plot it right.

Got it? So we? okay, that's the second half? Yep, now let's run. Let's see if we can pick this half to illuminate. Let's see if we can get it right. No, okay, uh, let's try that one.

Hey there we go and that is really very even I Like that. That's impressive. So if we get the next two up and that's not hard on the eyes at all. No, uh, when you have a large emitting surface like that, 3,000 lumens coming out of a large surface like that represents really quite low glare.

When you have 3,000 lumens coming out of a tiny little point source such as you can from some of the higher powered leads these days, it's a horrible amount of glare. There we go. I've ramped it up a bit there. Yeah, yeah, it's not easy to capture such a bright Source on a camera with background at the same time.

Do I look beautiful? You look wonderful. Oh, your hair's a bit messy though. It's got that, you know. Wind wind swept and interesting.

Wind swept and interesting, All right. So that looks that looks really quite nice. They flicker down at the low end, do they? That's what I've seen on the tests I did. Yep.

But we'll reverifying. Any flicker will simply be due to, uh, the Pwm frequency getting too low and starting to get into the visual range of 60 HZ 50 HZ 40 HZ Yep, and it might show up on camera. depending on the frequency as well, we might not see it, but it might sharpen. Yeah, exactly.

We'll try that cuz I'm shooting this at uh, 25 frames per second. Well, I get? Well, that's 50. Let's see if we can get. some big frequencies happening.

Interesting. So there, let's switch them off and have a close look at the back of them. Yep, uh. which actually won't reveal all that much? Oh okay, but we might also pull out the chalkboard and sketch up the principle of operation of panels like these.

Is there a brand? Uh, yes. These come from Ql Lead, Ql Lead in Shenzen in Shenzen? Yep. And there's the four. There's the four cables run now.

just a standard DC 2.5 mm, uh 5, 5, 5 mm y DC Barrel Also comes with uh, fastening Hardware that goes in there so that you can on the Roof Oh no, we can't see the I Thought we could see the board. Okay, no, they side attachment points. That's right, right? Okay, got it. And how much do these things cost? Uh, well.

uh, they're at a price which will allow me to sell them locally for just below $200 Awesome at this size anyway, right? Have you have you tried any other one? Hung low ones from not in flat panel emitters, right? I've got an unfortunate amount of experience Now with Uh LED Fluo tube Replacements which we're going to look at as well. We got a whole bunch of stuff here folks. We got LED Fluro replacement tubes and we've got these massive long ones which are locally manufactured locally manufactured by me. Doug for and Log Design P is over here too.

Hey right, Chalkboard time. Chalkboard time. Chalk! So Antiquated we we we. We have evolved somewhat I have't I'm A L Fair Call all right Douge, We're going to explain some of these lights, Are We? Yeah! So for those of you who aren't familiar with how flat panel light LED lights work.

you start off with a PCB loaded with bucket loads of little LEDs typically uh, 5050 package or 3535 or thereabouts. Okay, you then have a large slab of thick acrylic. It might be 10 mm, 8 mm thick or thereabouts, just standard acrylic. standard diffused acrylic.

Uh, no, actually clear acrylic. The clearer it is the better because what you're relying on is light. Hang on Chuck us another color got plent of colors light from the LED entering here. As long as that angle is less than the critical angle, it'll undergo total internal reflection and total internal reflection and it'll actually act rather like a Uh fiber optic.

Does that mean you need a narrow angle? LED Lens LED I Will come to that because that that is one of the areas of loss. If your angle of Entry is too steep, you get external reflection. Yep, so the light doesn't enter in the first place. If the angle is shallow enough to enter, it might still simply refract straight out there without traveling.

You'll also, uh, undergo some degree of diffusion in here, which is why some of this light will tend to reflect a bit like that simply due to surface irregularity. So you will get some emission here. You'll be reinforcing all of that with on the back side of it a layer of white reflective paper. is silver mirror better? Um, yes, but you want to avoid specular.

Reflections You actually want diffuse Reflections which is why you use white rather than silvered right? even though that's greater loss. Uh, no. because you can get you can get white surfaces which have got about 99.5 99.9% reflectivity. o It's just that when you do get a ray bouncing off them instead of it reflecting, it will diffuse.

Got it? And does that have to be totally flush with the surface? No, there can be an air space that's side of. It's not too critical. The other thing that you want on this face here is either a diffusion layer or sometimes that diffusion layer is actually etched into that surface of the perspect. So that's the key.

a A thin diffusion layer instead of diffused plastic? Yes, Aha. So you want highly conductive, uh, highly optically transparent acrylic so that you can get your light over to near the center Mhm without too much loss. but you still want it to diffuse so that you're not seeing the immediate glare from emitted from around here? Yep, and that's pretty much it. So your losses are uh, this entry angle Mhm.

Now incidentally, I Understand that Uh, 3M Have and probably others have a film which you can place I I Was going to say is there's some magic Gunk you can, there is some magic Gunk Haven't tried it, haven't tested it. don't totally know its properties, but is reputed to uh, basically get more of the light from the lead utilized within the acrylic. uhhuh uh. The other magic Gunk is the high reflectivity film here.

There's a few manufacturers of that around the place and more every day. and there are a number of plastics manufacturers uh I think the Bayer one of them who are getting into this material with the right characteristics on the front face for good diffusion. Got it? But bottom line is, it's lossy. It's lossy as hell.

Uh, even with the best will in the world, the transparency of the acrylic is finite, but that's what you. If you want a thin diffused Light Panel this is pretty much the only way to do it. Uh, I mean ultimately, would it be better to have your LED here and shine out. If fness wasn't an issue indeed.

the other way of doing it, which does yield you higher efficacy, but High manufacturer cost is a doy. Great big flat PCB plastered all over with LEDs Yep, and somewhere over here in front of it a diffusion layer mhm so that, uh, all the light emitted by these yep tends to give you a fairly good, uh, homogeneous light output, but I am imagining that wouldn't be as diffused as this solution because you would still probably see the point sources. Still, maybe as hot spots you can if you get the diffusion L too close to the LEDs you start see seeing the individual LED hotpots or you can go it with some magic Gunk perhaps? Uh, there are magic gunks. Uh, one type of magic Gunk I've seen is a a set of films Mhm.

Typically, you would also see these used on the LCD screens of laptops. Oh, got it? Yep, which laptops tend to use just either single uh, Ccfl tube or sometimes a raise of LEDs and they need a high degree of diffusion? They do. so. Yeah, you get consumers complaining about hot spots and you know, cuz that used to be the case on the old notebooks.

You get the hot spots in the edges where the and color shifts, etc. etc. Uh, it's an expensive solution though. Doing that.

Uh, the uh. the cheap expensive solution m is to use a simple diffuser space it relatively far away from the leads. yep and just plaster this with many, many leads as closely packed as you can. MH Uh, you do want tend to wind up with first of all panels which aren't as robust as this.

This is solid. This is solid. If you squeeze it, you can't feel any. Flex there's no give.

You can actually drive nails through that and nobody cares. And it still keeps on working. If you want to, we can try that. No thanks.

I I Have serious SE nailss driven through these and they just keep on working. Can't do that with this. It's going to flex. There's unless you have pillars in there to space that away.

they're not as robust. and I in theory you could make this panel flexible as well. In theory, if you use flex PCB and uh, you would have to have a gel type acrylic. uh, which would which you can do with uh, semi- polymerized pmma.

Oh okay, but I wouldn't like to try it myself, right? Uh, that's an experiment for others to perform. Excellent and we talked about the graph of the response of the light response across here. What's that going to well look like? Ideally, what you'd want is if you're getting uh, 100% here. Yep, at some point you're going to get 50% Mhm.

Okay, now that where it is we we don't know. and if that, what, whatever length that is in the same length, you're going to go from 50% to 25%. Yep, in the same length, you're going to go from 25 to 12% So in effect, it's a Uh in inverse Square law. Yep, uh relationship.

Ideally, if you've got a second Mhm batch of those over there to plan that half attenuation distance. Yep, so that the next one that you put over here cross in the center just about there and they approximately cross in the center Y And that will give you an approximately even light across there. So me seeing a hot spot in the middle is probably imaginary. It must be by Theory it must be down.

not NE Not necessarily not necessarily, because if it so happens that on this, the 50% Mark is there Mhm and there, then you'll actually get an overall brightness profile like that across it. Ah, of course it won't be like that. Yep, so it won't be peaky, right? It's just going to be a vaguely brighter in the middle. Or if it's the opposite, it's going to be vaguely Dollar in the middle.

Yep, it's not going to be extreme. Oh, except for ED effects where you might get a a huge increase in brightness of course. yeah, over at the edges due to Edge effects around here, we don't see with these panels. we don't seem to be getting a huge amount of that.

No, seems good for a one hung low brand. Oh panel. Yeah, they've done their homework. Yep, the efficacy is around about what you'd expect of such a thing.

I Have seen flat panels quoted at up to 70 Lumen per watt, but that would probably be for a horrible actinic dead you know, 6,500k color temperature with so much blue it burns. your retin is out and these are what? 4,000 Uh yeah, these ones are 4 4,000 so they match my strip fluos I Put in here recently. What? Uh, What most people are finding is that 4,000k is pretty much the ideal color temperature for uh, office lighting, task, lighting, paperwork, uh, electronics work that kind of thing. Uh, for domestic lighting anywhere between 2700k and 3500k, with most most people seeming to have a a vague preference for around 3,000k.

Okay, interesting. and where where to the 6 and 1 half th? you know those huge daylight ones? those 6 and2 7,000 even? Yes, yes, you use those where you just don't care about the quality of light, you just want quantity of light. Uh Street lighting tends to be a little bit that way, right? Uh, car park lighting? Uh, particularly. Uh Subterranean car parks and uh, outside your local clubs.

The car park out there so you get the greatest efficacy at yes at around 62k. Yeah, and the reason for that? Okay, um, where's a rubber? Rub it? Or and Raz it even sorry we can't do the uh, chalk scre. Okay, let's do a plot of wavelength versus intensity. Yep, leads are based on a Blue Lead Mhm which has got a spectrum a bit like that.

Yep, and you Chuck that into a Phosphor Mhm. The Phosphor uh, gives you your lower wavelength now depending on the shap, on the balance of blue light versus phosphor emitted light, and of course, the characteristics of the phosphor. The phosphor will emit light down here in the visible region or region. or, uh, if they've got a good phosphor, it might be a little bit down further towards the red.

right. Whenever you have a look at the characteristics of leads, you'll always see that characteristic like that. And it's the balance between the blue Spike and what happens down here that gives you your color temperature. Now a cool lead will give you.

uh. Well, actually pretty much what I've drawn there. Big blue Spike and maybe right that a wary will give you a warmy being about 3,000 yeah, will give you relatively low blue in comparison with your lower spectrums. Yep, Now there's also a characteristic of leads called the R9 coefficient.

A lot of the phosphors don't have much of the true deep red output. The R9 parameter tells you how much true deep red you get because a lot of the phosphors only really give you from your ready orange through to your Aquis. Got it? Incidentally that point there. the the Saddleback is usually just at Aqua right? and for some reason, well, actually we we know why.

Most leads are a little bit deficient in aqua, but your eye tends just not to notice it. Mhm because it's picked up on either side by the blue of the lead itself and the phosphor emissions immediately. That side got it. And you're doing work on underwater LEDs too.

Are there any tricks to underwater? LEDs Uh, Apart from the mechanical construction of doing underwater Uh, luminares, or underwater Electronics of any kind I Think the basic thing to recognize about leads or light underwater is that the blues are attenuated much more quickly. But they're attenuated primarily by scattering and got it. Let's go for the let's rub it again more. Theory Folks, this is all off the C We have no idea what we're doing here.

I've got no bloody idea what I'm talking about Most of the time if we're looking down on a swimming pool and we've got a light over here. Yep, if it's if that light is emitting red light, most of that red light is going to travel really well through the pool. Mhm. But you don't get to see it.

Why? Because it's traveling through the water, it lights up the wall over here perfectly nicely. But that doesn't give you a lot to see. The blue on the other hand, Fascinating. Ah, Do tell.

It attenuates relatively quickly. It might only go I don't know. Maybe 10 m would be the 50% point. but all of that blue is scattering.

It's not just being attenuated, it's scattering. And the pool irides is blue. and it's a beautiful sight to behold. Why do they? SC Why does it? Why does blue scatter? It's probably got something to do with the size of water molecules and chlorine or something.

Maybe you know, maybe it's different between salt water. Uh, no, no, no, no, Okay, and it it doesn't matter whether it's fresh water or salt water. although uh I Have seen learned studies which show the the transmission of light through Waters of different seas and they do have different properties MH But the differences aren't gross right? So maybe the physicist there can, uh, jump on to the Forum and tell us all about it. Why? Yeah, Bottom line is blue light in a swimming pool looks beautiful because the whole pool appears to glow blue whereas red? Yeah, whereas red light in a pool uh, transmits just fine but doesn't look any good.

Mhm. In order to make the uh, the redness of the pool equal to the bless of the pool, you've got to really pile on the red light. You' Got to have a lot. A lot a lot of red light.

And of course you do run the risk. like blues and greens in a pool look inviting. mhm I Don't think that anybody wants to dive into a yellow pool or a red pool. Uh, it's yeah.

Won't go there. W Go there. Let's not go there. Oh boy.

Okay, and what happens to these panels when they age or you haven't got the you haven't got good data on that yet? H We only got four years of data and only what what you mean? These one hung low panels last for you. Oh no no. I'm talking about the underwater lights right? Yeah, so uh I've been in the business for uh, you know, four years doing the underwater lights for a local company acquip and yeah, we've got four years of data. Uh, failures are incredibly rare.

It's delightful. Uh, the only real forms of failure they've had are if the Luminaire leaks. Yep. and they had a couple that did that.

Uh, do you seal them with a re-enter potting compound? No, no, you just don't bother. you. just rely on the O-ring seals and, uh, done with it? Yeah, in fact. uh, these are now.

They're basically, uh, glue sealed. Oh, okay, because there's there's no need to service them. Yep, they are work. or they're dead.

Yep, one of the other reasons for them being dead is inore. ERS Who forget that these are supposed to be low voltage lighting? R from 12 Vols AC We have definitely had a few that have had 240 volts put into them. The smoke has come out of the components. the Magic Smoke Yep, boy, uh, mind you on.

on the upside, we actually do have designed these such that the first thing that the power hits is, uh, basically Fus protection. serious fuse protection and parallel voltage clamping right? So when that does happen, uh, there's basically a wig Ling that blows. You know in, they're fused. So the potential for Destruction uh, explosive destruction within it is small.

Got it? And it means that nobody's going to get El electrocuted diving into a pool that some Wally has wired up uhhuh just as an As side. Uh Queensland has recently passed laws stating that you have to be a qualified Sparky to do work on certain aspects of swimming pool lighting even if they're 12. Vols even if they're 12 Vols Anything that requires anything that doesn't simply plug together a logical sequence that is impossible to up, anything that requires a screwdriver or joining of wires needs a qualified Sparky Doesn't matter whether it's the 12vt side or the 240 volt side. Got it? It has to be blindingly obvious to Creton how it goes together or else you have to be a qualified Sparky That's Queensland for you? Yeah, Beau One day crazy the next? Yeah.

I Was about to say look, maybe they've got a high proportion of uh cretons I Don't know what the reasons for the laws are. Hi to all my Queensland viewers. Yeah, yeah. I Do not respond to emails.

It wasn't me, it was somebody else. And what happens to these lights when they age? does the do? They just reduce in intensity and the Spectrum stays the same. Yes, the third uh, form of failure that we've discovered is chemical contamination of the LEDs Oh okay, we kicked off using Cre XR leads, which are actually more subject I think to chemical contamination than most of the current crop of leads. Why is that physical? Yes, it's It's their physical manner of construction.

Got it? And we don't know if. Uh, and we actually sent these leads back to Cre for examination. They weren't able to tell us what it was and they did put them through their Labs All they could do is shrug their shoulders and say, well, yeah, it's chemical contamination. But here's the interesting thing.

We suspect that it might be Ingress of some form of chlorine. Vapor Oh, and uh, the leads are susceptible to things like chlorine. Vapor Um, various volatile organic compounds. You see this on the underwater LEDs not the regular shop ones.

Correct? Oh, mind you, we've also seen them in the regular shop ones where they've been operated next to stock piles of pool chlorine. Oh, there you go. And what happens is the dyes on the leads go dark. not only low emissivity, but the actual die looks discolored and ugly so you can physically see the we on them.

Yeah, the contamination. Yes. and the the output drops to a tenth a 50th of what it used to be. Wow.

You can resuscitate them. Do tell you operate them at very high temperatures like 85 to 100. C On the die for. about a fortnite 3 weeks a month, they come good again.

Do you have to do it on the die? Do you have to light them up? Or you can just put them in a thermal oven and bake them. You could probably bake them, but we did it the E selfing. Yeah got it. They're not fit for resell or anything, but the fact that you can revive them from chemical contamination is absolutely fascinating.

That is fascinating. So how did you know the D temperature? You measured the back temperature and then you know the uh thermal conductivity of the We. We know what the thermal conductivities are. We know the input power to the LED So hang on down to the drawing board.

Okay, down to the Whiteboard Again, here we go. Uh, if you've got a LED uh sitting on a heat sink mhm, you know what the thermal resistance is. from the lead dye to its solar Junction point. You do cuz that's in the data sheet m You can measure what the thermal resistance is from.

The Junction point to the heat sink fins because you can get a thermal couple on that. You can get a thermal couple on that measure the difference in temperature. You know how much power you're putting in. The math is easy.

So bottom line is if you put enough power into this to get the heat sink up to say 85 C and you know that you've got say, well I'll plug some numers numbers out of the air. 10 per watt there and maybe another 5 per watt there total of 15 if you put a wat into that Mhm and it's enough to get the heat sink up to 85. You're looking at 100 on the chip. Yep.

Simple. I've done a video on that uhuh LED Lighting gez that was a couple of years ago. Now Yep They're still going my the leads on my deck. Yeah, we're not talking about high level calculus and integration.

It's pretty dumb stuff. Yeah, it's yeah. it's a series series. resistance.

Oh law HS law type thing you. Yep, power is current and the thermal resistance is the resistance and the temperature is the voltage. There's the electrical parallel there, no pun intended. Too easy.

All right, and that's all we need to know about Leads Le 101 for the moment. Yep, brilliant. Thanks Douggy! So with a little bit of luck, let's check out the RF remote on these panels. Sorry, but we're gain in here that is fading down.

Yeah, now. apparently we didn't quite start with both of them at full ball. No, can you see a little bit of residual flicker on the left one? I Can see flicker on the camera here. These these linear ones here have no Ripple Mhm so they won't be responsible for any strobing.

Yep, they Pwm control so. but yep, we don't know what what Pwm frequency they're running from. So no, none of the ones when stored up in the ceiling here are Pwm at all. No, they're all constant current.

Yes, right. But in of your Fluos Y will have 100 HZ Ripple They will. There you go. And we are recording this at 25 frames per second.

Okay, now let's see if. okay, that looks as though they're both up full now. All right now. It might also make a difference on where the actual controller boxes are.

Yeah, it might may. Who knows. Okay, so fading down, fading down and down and down and down. Down and down.

We got a pretty good control, right? R The fact that you can get them down to? yeah, that's pretty impressive now. Visually got this camera set to uh, fixed? uh exposure by the way. So come on. Okay, that's as low as they'll go.

Yep, and coming up and that looks like pretty much full B Mhm Yeah. I'm seeing no strobing at full brightness here on the LCD screen of the camera, but when it was halfway I was seeing significant strob. When it's at 100% And 0% there will be no flicker content MH because the PW is either going to be full 100% or nil. But yeah, as soon as you start fading a bit, you should start getting some strobing there.

Yeah, getting some strobing now? Yeah, not sure if this was sharp on camera folks. but bucket loads of light. Oh, that's really really sweet. I Like it.

Not bad for a one Low Chiy? Yeah and these are 60 W Yes. Rated 60 W output Yes. Got it all. No Rated 60 W input It's input.

Sorry, Yes, of course 3000 Lumen 3,000 Lumen output Yeah, what's a regular office Fluro in Lumens? Uh, call it 70 lumens per watt. For plain vanilla cubes, you might get 9 lumens per watt for a quad phosphor Yeah, which is what I got and some of the new Quad Phosphor T5 tubes which can only be run with electronic ballast. They're the very, very skinny ones. Oh yeah, uh.

they can get in excess of 100 lumens per watt, but don't put your money on them, right? And the other thing about Fluo tubes of any type, of course, is that their efficacy varies hugely with with temperature. which is why you get the warm up effect that we noted before. Yep, and which is also why at low temperatures below 15 10 C Quite often when they first spark up, they're half as bright as a dead gloworm, and they perform incredibly badly in subzero temperatures. There you go.

Leads Rule. Yep, none of this compact fluo rubbish, right? Well, compact fluos are just a variant on the fluorescent theme. Oh yeah, they look, they serve their purpose as a stop Gap solution between correct incandescent and leads. Look, you'll see them round for half a dozen more years, but leads will take over definitely.

Oh I Thinkin A decit, Exactly. And we're starting to see more and more solutions using LEDs that don't necessarily conform to your usual bayet socket plug it in type lamps. There's still definitely a place of B at socket plug it in lamps because there's billions of such lamp bases in the planet, Exactly. But new lighting can use different form factors like these ones which aren't just a slot in replacement.

they're a new lamp unto themselves. These strips up here, they're a new lamp unto themselves. I Can see these going into these flat panel ones, going into all the all the uh Mansions the you know cuz they look pretty Jazzy particularly if if they're in 3000k color temperature right which is some. it's the preferred color for domestic applications because it's fairly close to that that you would get from an incandescent lamp anyway.

see.