Welcome back our first series, which involves the whitening of a sales area. In the last part Ipresented the LED and the LED selected by me to the cooling and called a way to attach the LED. In this part, I must unfortunately rebuild a portion of my LED project and upside make, because some things that do not work, how I actually imagined that. Who knows what it’s all about and what possible Approach there was for this project, not even once in the first part of this series look should.
The Actual Plan and Where the Problem Is.
Yes my plan was to provide recording and then into a lamp socket to screw every single LED with a GU 10 actually. Similar as we know it from home, and where it’s everywhere already done (who wants to replace private even his lamps with LEDs, and that without any tinkering, if necessarily this Advisor read). The cause of the problem is just that I found absolutely still no driver, which delivers the desired performance and is small enough for the version. Also I had considered just as a lamp socket this display light to take.
Stylish looks they already and would be very good on the ceiling. Also, the LEDs on a metal t carrier must be attached. There, the terminal would fit quite well. But €8 per lamp receptacle is of course also very intense.
How Much So Far Is the Single Lamp.
The cost per LED is now pretty high and that’s why I’ve listed times, how much so an LED actually is now strip out the development time and the construction. So purely material costs:
- CREE MK-R LED: €15
- Heat sink: €6
- Additional heat sink €5 (apart built LED)
Is a proud price from €26 for a LED 1350 lumens at 1 A power supply together. And since no constant current source or Assembly is yet!
Looking for Cheaper Alternatives
Here the first angle on the heat sink. Second angle, which is linked to the first, you can then later also align the lamp and adjusting.
I looked around me so, to find a more cost-effective mounting solution and since I am a mechanical engineer, I thought to myself: “why don’t you take 2 angle and screw that on the 2nd heat sink on it?”
Said than done. I have the piece brought me 2 then angular at the hardware store for 50 cent, screwed it together and fastened together at the small round heat sink. The angle itself would then attach the steel girders with a small screw.
Together, I’m with it at a cost of nearly € 3 and the LED can be aligned well with this type of attachment. Maybe not so stylish like the expensive display light, but still very usable. And who, please look at the lamp mounting height of 5 m, if he wants to look for clothes? Probably no one.
When I add this to the €26, we are currently already at almost € 30 incl. fastening. Pro LED mind you!
But A Question Remains: Which Driver We Take for the LED?
We have selected the LED already and now we need a suitable constant power source for the LED. I had already betrayed Yes at the beginning of this Blogteil that I found no suitable driver. But there are still many other drivers that come into question. Although you do not fit into a lamp socket, but since we have an inverted t-beam on the ceiling, is there enough space to accommodate larger drivers without problems. Since we already know the necessary specifications of the LED, not really many possibilities remain. We must seek just a bit on the Internet a constant current source according to, which 1 A delivers current and is within the voltage range of the LED. Here, we have to switch the way the LEDs in series and thus maintain multiple LEDs with a driver. So the possible configurations are:
- 1 A 12 V
- 1 A 24 V (2 LEDs in series)
- 1 A 36 V (3 LEDs in series)
The drivers I am careful this time and would like to use only from reputable manufacturers such as Mean well. Really much choice does not exist in this area so really, so I just ordered the Mean well L P C-1050 with LED-9 our site for about €20 incl. shipping. Once called, and it was there the next day via D H L. Just great guys!
It went right out of the box at the fairs. Since the Mean well maximum 30 V, you can switch also maximum 2 M K R LEDs in series. Turning even a 3 LED in series, switches the power supply in a kind of “safe mode”. It quite clearly shows the user that it’s overloaded by it starts to Flash.
Readings with 2 LEDs:
|Input||109 m A||234 V||25,65 W|
|Output||1050 m A||24,24 V||24,62 W|
OK, that looks pretty good already or?
Without a Lens No Concentration of Light – and no Illuminated Clothing.
Now we have the bracket, the LED itself, the driver and now still a lens or a reflector to focus the light also targeted on the clothes. Here I’ve thought over again 3 possibilities. For one, there is a lens which I can directly place LED to the and it is directly fixed there by a gripping effect on the body of the LED, then there is a special reflector for the MK-R LED and finally again a lens that I expanded from a COB-China-LED.
First possibility: the clip-on lens.
Simple and easy as I did it already here and here, simply attach and finish.
Second possibility: the reflector.
Also quite easy.I thought anyway. However, the producer has not considered that there is also cable. The reflector is plan and provided with an adhesive pad on the bottom. With the Dremel, I had to remove a portion of the plastic to be able to bring the reflector on the LED. Actually a very nice light, only the Assembly was anything but easy. Third possibility: the COB lens.
It was now again typical Christian. Always have me as a stuff invade. But good. I would, if I would try to get the best. It was more of a coincidence, because I’ve got a COB LED from China a few days ago that had screwed up a great lens front. This I have taken out and kept on my MK-R. The result was a very nice light cone with sharp edges. Only problem on the thing was: how everything in the world should I attach this lens? After some pondering I have simply taken an aluminium tube, stuck the lens there and it is simply placed over the LED. So again a fairly simple method.
By the way: I took this aluminium both also at the other just to prevent lateral stray light, what could possibly hide. A LED is yes a point light source and anyone who looks at this point, will it still a while as blue or green point in the eye. It is here also a safety device, so nobody can watch LED into the side. I ran the cables backwards through the cooling fins of the heat sink for all methods. You should make sure really that the cable as far as possible of the LED are discarded and when it comes the light beam will be unchecked because the cable is otherwise extremely can heat up. After all, we have to do it here with high light energy. We remind us of the LED efficiency. About 1/6 tel of electric energy inside the luminous flux. It now holds his hand over it she is already quite quickly quite warm. Each of Physics in the high school had should probably remind of photons, particles of light, and light energy.
While I generated now still an additional surface as a heat sink with the aluminium tube, but this additional surface has a few minor side effects. The inner part of the apply is heated in addition still by the luminous flux. It is thus absorbed a part of luminous flux. Additionally, the LED is no longer in the open air, but in a kind of ‘Chamber’. The aluminium tube and the lens. These two factors can be the temperature after 2 h burn time to rise to 71-73 ° C formerly 70 ° c on the LED. So despite the larger surface a higher temperature. Nevertheless, we are still below the 85 ° C from the table of the data sheet of the LED.
The 3rd has a slight advantage this solution yet. I can determine the angle itself! Depending on how far away is the lens of the LED, the beam angle changes. Can easily be read in optical physics. In my case, I have placed the lens away approx. 15 mm from the LED. This makes a reasonable angle of 44° then (arc tangent of half of the diameter of the light beam on the wall divided by the distance to the wall is the half angle)
At the End of the Day, The Customer Decides What He Wants to Do.
Now is just the question what my customer, so the company wants. Does he want a light beam with a strong definition or he wants to have a softer light cone. You can find an answer to this question and how the finished lamp, in the District of the Blogreihe, which appears exactly in a week today.
Until then, can you even already appeared watch parts in the or you just look around on the blog. You will find certainly enough exciting reading material:
Update: Now all parts of the series are on line, here the entire table of contents:
- Part 1: the project whitening a sales Hall
- Part 2: The choice of the LED and the heat sink
- Part 3: Housing, lens and costs
- Part 4: The shadow and the diffusion disc