Show me where someone, anyone, said they prefer a 60w incans worth of light? I said, you get buckets of light, in an uplighter scenario, from a 60w incan (not thats all you need). You can get more lumens from the XH LED than a 60w incan, at stock levels, so there is no need to build in heat? Why is that so hard to accept?
The difference between an uplighter and an ordinary bulb in the ceiling is the direction, and 60 watts was a staple for many rooms for decades. In fact many housings, light fittings, limited the bulb to 60w. Again, not saying this is all you need. Im saying the LED at stock levels will outshine the 60w incan by buckets of lumens, you can, but do not NEED to build in heat.
But if you want reasons not to go beyond specs. Home insurance. This is not a torch in your hand with short bursts of limited use, or a charger you will keep an eye on in the garage/patio outside in its heatproof tin box lined with heat tiles or bricks inside a kevlar bag. Youre not going to turn it off if you leave the room to make coffee or answer the door, and get distracted. You could be away from it for plenty of time, hours. You can argue you will take this precaution, that precaution, but you wont, its just easy to type that you will, reality is far far different.
Please no arguing, the goal of this project is to create the XHP70 chip lamp at 2.4A output, different options including less or more lumens and different LEDs will be the next step when this project is done, therefore everyone should be able to make a light they want.
According to texaspyro he designs lights to shed 100% of their energy consumption, which is a very reasonable way to design heatsinks, and allows for an extra failsafe, and its one i intend to follow.
If you decide to create this lamp and use no heatsink or a much smaller one then there is nothing i can do, but the original design will be with extra safety in mind. You can modify the final design in any way you wish, which is the beauty of it, unlike buying a light at the store you can take this proven design and adjust as you see fit (and of course any safety concerns that arise are your responsibility). I intend this light to be certifiable if built according to specifications provided, however i can’t get it certified and i can’t take any responsibility for house fires or anything else, i am not a business and the final specs will CLEARLY state you build and use at your own risk, and you would be responsible to get certification for the light if you wish and you should be able to since it will designed to meet any certification requirements.
Again I’m not here to argue with you, so please make any future posts relevant to the advancement of this project if you intend to be involved.
Princess if you dont want people to argue dont cause it.
I never said smaller, or no heat sink. Try reading my posts alone, ignore wights, and you might be closer to addressing me. At this point, you too are adding to the fire as youre arguing with me, about things Ive never said, as if I did.
OH s**t a brick, please stop arguing about the difference between “half a dozen” and six.
Some members are interested in following this project, and not at all interested in a pi**ing contest.
The OP stated ” the goal of this project is to create the XHP70 chip lamp at 2.4A output ”
Is it at all possible to let this happen from here on in.
I’ve had some experience (limited) with certification in EU, and It was cumbersome and expensive, we had to pay a lot for bunch of tests to a certified certification company. Not sure if we as hobbyists would be able to accomplish that.
So to get this project rolling, we would first need to agree on requirements.
i.e.
Total lamp assembly (lamp housing, stand, psu, control electronics, led, heatsink)
or
I am told CSA certification is easier then what your describing, but i doubt we can get it done for an DIY set of plans, and anyone building the light for themselves will have to decide if they want it certified, i do hope somebody does for validation.
So far i have no concrete parts aside from the LED, i hope once this one is finished it will be a blueprint and modifiable and expanded for multiple XM-L or XP-L in series and other possible configurations, but getting this light designed is the first step, changes and other permutations come afterward.
https://www.fasttech.com/products/0/10001927/1173707-5555100mm-aluminum-heatsink
Might think about something like that with the led on the pointed upwards at the bottom of a thin white plastick tube, or a clear plastic tube with some sort of diffuser wrapped around it. Should make for a nice futuristic look and really help with the thermal convection, also all the weight will be at the botom so it will be less easy to knock over. Im probably going to do something of the like in the near ish future, depending on some shenanagains with some 5050 strips.
Maybe those three from MeanWell can also be used (min. voltage is 12V, a little too high):
HLG-40H-20B
HLN-40H-20
LPF-40D-20
If you want to use two XHP70 in series, you have another few Meanwell options (in the 2-2.5A range):
HLG-60H-30B
HLG-80H-36B
HLN-60H-30
HLN-80H-36
LPF-60D-30
LPF-90D-36
Another important thing: if the XHP70 consumes 35W, it doesn’t mean you need to dissipate 35W of heat - that would mean no light would be produced. Instead about 1/3 of the power is converted into light, so you only need to cool off the other 2/3.
I have 2x300W standalone floor lamps that fill 4mx5m room with a lot of very nice soft light and I wouln’t want to get much less than the 300W halogen is giving now, so perhaps I’d need 2 XPH70.
Another thing - the XPH70 currently is only available with perhaps too high/cool K rating, above 6000K. 2700-4000K is what I personally would prefer, the less the better. The lights are mostly used after dark, and too cool bin wouln’t look so nice. If using it to augment already existing daylight, you could use cooler tint, but after dark would be better to have warmer. My opinion anyway.
it’s a matter of taste. Some people are happy with a bare clear light bulb on a ceiling, others prefer maximum flood light from many sources. I prefer to have soft light bouncing of the ceiling, and avoid at all casts bulbs providing down cast light. So I’d put 2/3 of my available lumens in a room to bounce off the ceiling. I was under impression that the very purpose of the floor lamp is to provide lot of flood lumens bouncing of the ceiling. We of course would need to settle this before proceeding, agreeing on expectations, conditions and requirements to be met.
While they have non in stock at the moment they must be expecting them as they are advertised and priced, also Cree must of announced the range for them to know what is what. http://www.cutter.com.au/products.php?cat=Cree+XHP70
Pick a bin/temp and wait
Serifus: The LED is going to draw about 31W so that won’t be big enough. Light diffusion is an interesting idea worth looking into
Surprise: Those supplies look good and are first on the list. They are not in stock, and the slight under driving is not a huge concern. I am going to assume the driver will be able to handle current control so more then 2.4A maximum is acceptable (lets say 3A max). For now i am only looking at one 12V chip, once this light is complete more chips will be on the list for the next one. You are correct that 31W of heatsinking are not required, but for an additional measure of safety the heat shedding is being designed to match the LED load. Also you suggested the same heatsink as Vex below, thanks
Vex_zg: Both look like a good heatsink, both options are worth considering at this point until we have some more devices and data. Does anyone know someone who can do a solidworks or other heat shedding calculation?
I also prefer 3500-4000k but i assume that will become available soon enough
The drivers are all current-controlled: they deliver exactly the rated amperage (by measuring it and adjusting voltage), and you can optionally dim (reduce amperage) by connecting a 1-10V dimmer or other supported means. Some LED power supplies are controllable by DALI, others by KNX, variable resistors, or PWM.
Oops, you are right! I looked only at the first suggested heatsink. Other candidates are from Nuventix:
I already have 2 of the 90*90*74mm ones linked, I’ll see what sort of experimentation I can do along the lines of chimney convection cooling. I dont have much curriendly available as a heat load, mostly just xml2’s. But ill see what i can do. I guess this gives me an excuse to buy an mtg2, then wait for the better tints to become available
1. We will need to run cables from the floor level to the LED
2. We will need a pot to regulate current, around the middle of the height (floor pots are nowhere near as usable, IMO)
3. We will need to dissipate some heat
I’m thinking about designing it like this
1. Use a hollow pipe, aluminum, copper, whatever is cheap, If single pipe is used it has to be of little bit bigger diameter (I estimate around 1”) to provide stability, if two are used they can be smaller diameter, 1-1.5cm each.
2. Run the cables Through the pipe
3. Mount the pot in the pipe
4. Thermally connect the LED star with the pipe, so that the star sits on top of the pipe, maybe press fit a pill, or solder a copper star onto the pipe, or a copper shelf
5. Add heatsink around the pipe http://www.imexbb.com/Images/11501456/led-light-heat-sinks.jpg
If we could find good mathching combo pipe/heatsink, this would be an elegant solution, using the pipe to channel cables and heat, and serving as the shelf for the star
meaning if X watts are dissipated to it, it will provide a certain temperature differential above the environment temperature.
So, to pick one, we need to know this:
1. How much waste heat we need to get rid of
2. What is the highest allowed temeprature for the LED
3. What is the highest expected environment temperature (could be 21, or could be 35*C, depending where you live)
I wouldn’t trust specified *C/W ratings until retested under our conditions.
input specs:
3 *C/W heatsink
30W dissipation
60*C max allowed LED temperature
35*C max ambient temperature
calculation for those specs:
3 C/W 30W = 90 *C temp differential
if the max ambient temp would be 35*C, that would give use 90*C+35*C=125*C max LED temperature
So we need better heatsink than 3 *C/W
1. What is the expected dissipation?
2. What is the max temp of the LED die ?
I see that they did luminosity vs. temperature tests up to 150*C, but they also mention “binned at 85*C”, so I’m not clear what the max temp is from these specs.
