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50W COB 30V-36V LED minitest from China - will it really be 50W?

p.kaczmarek2 7326 39
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  • 50W COB 30V-36V LED minitest from China - will it really be 50W?
    Recently, I found an offer to sell a COB LED module with a power of 50W. I decided to check whether the given parameters really correspond to reality - below I put the results of my test.

    50W COB LED module purchase
    I found the diode on eBay under the slogan 50W LED Chip COB 30V-36V Cool white Integrated Bright Bulb beads for Floodlight for less than 2 euro:
    50W COB 30V-36V LED minitest from China - will it really be 50W?
    The seller is of course from China.
    COB in its name is an abbreviation of "Chip on board", which means that this module is a few or more LEDs in one housing as a single module.
    50W COB 30V-36V LED minitest from China - will it really be 50W?
    The module has the following dimensions:
    50W COB 30V-36V LED minitest from China - will it really be 50W?
    The seller provides the following parameters:
    Quote:
    Power: 50W
    Working voltage: 30-36V
    Current: 1500mA +- 5%
    Brightness: 4700LM
    Dimensions: 52mmX40mm

    Knowing the aspirations of some sellers to overestimate the parameters of their products, I decided to see if this diode actually reaches 50W - the results below.

    Test environment (TP-1603 power supply)
    Good cooling is necessary for such an LED module - even if we want to run it only for a moment. It shouldn't be turned on without a heat sink at all.
    For this reason, I also chose one of the larger heat sinks I had at hand and drilled four holes in it for mounting the module (although this heat sink should be much bigger , especially for continuous operation):
    50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W?
    50W COB 30V-36V LED minitest from China - will it really be 50W?
    I used thermal paste to improve the contact between the LED and the heat sink.
    Of course, this module is powered by direct current. The poles of the module are marked on its housing - just take a look. I soldered wires of the appropriate colors to the leads:
    50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W?
    I used the TP-1603 laboratory power supply to power the diode. It offers voltage and current regulation in the range of 0-60V and 0-3A. Additionally (in order to verify the measurements) I used a UT210E clamp meter and a BM857s multimeter to measure the voltage:
    50W COB 30V-36V LED minitest from China - will it really be 50W?

    Voltage / current measurement results
    Such LEDs should be energized current source , that is, constant current, not voltage. This is because the voltage drop across a diode changes with its temperature, which if powered from a voltage source would result in a change in current as it heats up, which could eventually burn it.
    That's why I used my power supply as a current source.
    I gradually increased the diode current. The diode started to glow slightly at 0.01A current and 25.5V voltage.
    I quickly realized that this LED was REALLY BRIGHT. Even at lower tensions, a brief glance at it makes us see a 'trace' of its brightness in front of our eyes. I advise against anyone irresponsible experiments with such strong light sources, you can damage your eyesight.
    I allowed myself to pull the test up to 2A with the full awareness that it might end up damaging the module.
    Between subsequent tests, I took breaks so that the heat sink could cool down.
    Below are photos of measurements:
    50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W?
    50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W?
    50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W?
    I gave the measurement results to the table:
    Current [A] Voltage [V] Power [W]
    0.01 25.5 0.255
    0.02 25.9 0.518
    004 26.2 1.048
    0.1 26.8 2.68
    0.15 27.4 4.11
    0.25 28.2 7.05
    0.5 29.9 14.95
    1 32.4 32.4
    1.5 34.4 51.6
    1.75 35.3 61.775
    2 36.2 72.4

    Of course, if you observe the diode for longer, you can see that the voltage at a given constant current value changes - this is what I mentioned earlier, the voltage drop of the diode changes as it heats up.
    The diode actually reaches 50W with a current of about 1500mA, although of course some of this is deposited as heat and not light.
    My little heat sink works well only up to 500mA (less than 15W power). Probably a cooler from an old desktop computer would work better here - you can get it occasionally from electronic scrap.

    Summary
    This LED module actually has a power of 50W as stated by the seller. It is really very bright - much brighter than the bulbs we usually meet. Inherently, it also heats up quite a bit and requires a large heat sink (probably larger than the one I used for the quick measurements).
    Now you could think about using such an LED module - do you have any ideas? Maybe a portable flashlight?

    Cool! Ranking DIY
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    About Author
    p.kaczmarek2
    Level 24  
    Offline 
    p.kaczmarek2 wrote 1079 posts with rating 1445, helped 94 times. Been with us since 2014 year.
  • #2
    prosiak_wej
    Level 34  
    p.kaczmarek2 wrote:
    do you have any ideas


    The best application would be for a DLP projector instead of a xenon lamp. Unfortunately, many models carry some secret communication between the lamp module and the processor and it is not enough just to simulate a signal like "lamp is on, current is normal" and substitute the LED. I have such a NEC, in total fully functional, only the lamp has already run out and I can dream about replacing it with LED :(
  • #3
    Tomek515
    Level 22  
    I recently played around with a similar 50w module and to use fanless cooling the heat sink would have to be huge. I applied 6 times the size of yours and it was still low after a few minutes.
  • #4
    p.kaczmarek2
    Level 24  
    prosiak_wej wrote:
    Unfortunately, many models carry some secret communication between the lamp module and the processor and it is not enough just to simulate a signal like "lamp is on, current is normal" and substitute the LED.

    And it's not something "relatively easy" to eavesdrop on, I2C type? For example via Bus Pirate or something more serious?

    Tomek515 wrote:
    I recently played around with a similar 50w module and to use fanless cooling the heat sink would have to be huge. I applied 6 times the size of yours and it was still low after a few minutes.

    It heats up very much, as I wrote, with this small heat sink I can leave it for a few minutes for a few minutes, and at 50W it heats up much faster.
    Maybe I'll try soon with a cooler like this:
    50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W?
    but in general, at the beginning I just wanted to check if it really brings out the parameters given by the seller - and it is.
  • #5
    prosiak_wej
    Level 34  
    p.kaczmarek2 wrote:
    And it's not something "relatively easy" to eavesdrop on, I2C type? For example via Bus Pirate or something more serious?


    There were already topics here, people were analyzing, unfortunately the copied fragments of messages only worked for a few minutes.
  • #6
    pawelr98
    Level 38  
    And did your colleagues not look at the hardware side?
    Ie how the module knows the lamp is on and is working well.

    It was fun to play with the Sanyo VCR to make the main processor feel as if it had all the sensors in the right position. All the voltage values in the on and off state were measured one after the other, and then pulled up to the ground or power supply. And this only to show that you need a second processor to control the head.
    So much trouble for the factory VFD clock to work without the rest of the motherboard.


    As for the LED. The fact that it keeps the 50W for some minutes does not mean that it will withstand such use for a long time.
    With stronger cooling, leave it for a few hours (after the temperature stabilizes at a safe level) and then conclude.
  • #7
    Kajox
    Level 16  
    The power is still half the trouble, I wonder how many lumens these LEDs have. I have been using them for several years in the conversion of a Makita dml185 flashlight using this COB. A few years ago, the modules were on a thicker metal core. I thought that now they are making some economical versions, but in terms of durability they do better. I have a round heatsink from an old GPU with a fan. The heat dissipation is quite large, the diode is around 60 degrees Celsius. The emitting power on the diode oscillates around 40W. I made 5 pieces of these flashlights on ordinary Step-up converters.
  • #8
    DamianG
    Level 20  
    Kajox wrote:
    The power is still half the trouble, I wonder how many lumens these LEDs have.

    I was waiting for someone to write it ;) Power doesn't really mean much. The lower the forward voltage a diode has, the better - it gives off less heat. The second module of the same type can have 1.5A@30V, that is "only" 45W, and it will emit the same lumens.
  • #9
    zgierzman
    Level 27  
    I made a bad impression about Chinese modules. They have problems with durability.

    About 2 years ago I bought 50W modules, but mains powered.
    I mounted three pieces on a huge heat sink, about 30 x 50 centimeters removed, from an inverter. The cooling was sufficient - after an hour the heat sink was noticeably warm, but it did not burn the hand - maybe 30, maybe 40 ° C. I installed it over an additional workbench, it shone sometimes for a few minutes a day, sporadically longer, sometimes for days and weeks - not at all. If I had to estimate the total time, I would say: maybe a hundred hours, maybe a few hundred, far from a thousand ...
    After two years, two of the three modules are no longer functional.

    50W COB 30V-36V LED minitest from China - will it really be 50W?
  • #10
    szeryf3
    Level 21  
    A flashlight might be a cool thing, but you'd have to think about the power problem and most importantly the cooling problem. This last point would be hard to jump over. See that even these small COB flashlights are metal and very warm after a short time.
    I used to watch a movie about top shelf COB flashlights, they have an interesting function. The electronic system "watches" the COB temperature so that the critical value is not exceeded.
  • #11
    speedy9
    Helpful for users
    zgierzman wrote:
    I mounted three pieces on a huge heat sink, about 30 x 50 centimeters removed

    The question is whether such a heat sink was suitable. You did not write anything about its shape, but for LEDs, a smaller surface radiator will be better, but a "thicker" one with numerous ribs. In my opinion, the CPU cooler will be better. It is important that it is properly selected, because an ordinary "box" CPU from 45W may not be enough.
  • #12
    zgierzman
    Level 27  
    speedy9 wrote:
    You did not write anything about its shape, but for LEDs, a radiator with a smaller surface will be better, but "thicker",


    Thick and ribbed. Suitable for heat dissipation from large inverter IGBT modules, so it should perform no worse with LED :-D I wrote "heat sink" and not "piece of sheet metal". In the evening I will post a photo if anyone will drill down the topic.
  • #13
    speedy9
    Helpful for users
    It should actually be OK. Unfortunately, probably the power supply of these modules is designed to operate on the edge of critical values. Similar to LED "bulbs". Reducing the current in them by 10% should not significantly change the brightness of the lighting, and can significantly extend the service life. Only that everything is integrated on their PCB and there may be a problem with that.
  • #14
    pawlik118
    Level 27  
    prosiak_wej wrote:
    p.kaczmarek2 wrote:
    do you have any ideas


    The best application would be for a DLP projector instead of a xenon lamp. Unfortunately, many models carry some secret communication between the lamp module and the processor and it is not enough just to simulate a signal like "lamp is on, current is normal" and substitute the LED. I have such a NEC, in total fully functional, only the lamp has already run out and I can dream about replacing it with LED :(


    Rather, it will not work due to the poor CRI (probably about 60) and a completely different shape of the LED light spectrum from xenon. Added to this is the shape of the light beam.
    Clarity is not everything. Poor CRI means that even with high light intensity, human eyesight will "see poorly".
  • #15
    GanzConrad
    Level 23  
    DamianG wrote:
    I was waiting for someone to write it ;) Power doesn't really mean much.

    zgierzman wrote:
    They have problems with durability.

    I was waiting too, because it is difficult to write about the same ...
    I know that I will sound like a stereotypical "electrode guy", but it has all happened already, dozens of times.
    Even the thermal paste used is not a thermal paste but silicone and is not suitable for COB 50W - I would use at least MX-2 myself. The radiator is not polished, I do not mention the polishing ...
    The author would have known this if he had searched a little, instead of throwing in another, meaningless "tests".
    The fact that the LED can be loaded with 50W only gives us information that such a COB is a good resistor, and does not give us information on how much light it will emit, how much heat and how long it will work under full load.

    szeryf3 wrote:
    A flashlight could be a nice thing

    Normal nobody makes a flashlight out of it, because in flashlights you save electricity from the battery, and this COB produces mainly heat.
    I recommend the channel:
    https://www.youtube.com/channel/UCn6sN4bKlFUF0YXNbdea7hQ

    speedy9 wrote:
    Reducing the current in them by 10% should not significantly change the brightness of the lighting, and can significantly extend the service life.

    Even 50%, I checked on others and I doubt there will be a breakthrough in technology for the price of $ 2 for 50W ...
    Above 1/2 of the rated current, the amount of light increases minimally, most of the power goes to the whistle.

    pawlik118 wrote:
    Added to this is the shape of the light beam.

    Exactly: lenses etc. "river" theme, but that was also ...
  • #16
    p.kaczmarek2
    Level 24  
    GanzConrad wrote:

    Even the thermal paste used is not a thermal paste but silicone and is not suitable for COB 50W - I would use at least MX-2 myself.

    You have not read the topic, this heat sink, even with the highest-quality paste, would be too small for this diode for continuous operation and was used only for the first starts.

    And as for "how much will it work under full load", you are right, but if we wanted to check it, it would be worth checking on several (or more) pieces from different batches, to rule out the possibility that we just got it one faulty one that broke after a few hours.
  • #17
    zgierzman
    Level 27  
    GanzConrad wrote:
    The radiator is not polished, I do not mention the polishing ...


    I would not go to extremes. I can show you heatsinks on which IGBTs are mounted for currents of 1600 (say: sixteen hundred) amps.
    Even those in the appendix, with a current of 1200 A, with a Vce above 3 V, they give away> 4 kW as heat. A datasheet says: "total power dissipation Ptot 7800 W". And all this on a small contact area with the heat sink.
    The standard of the contact surface treatment does not differ from the average heat sink from a computer processor. It is probably even lower than in the more expensive models. There is no polishing or similar treatments. And yet it works, so hitting 0.3% lower thermal resistance is rather a fad, since large companies producing for industry do not bother with it. I watch a lot of it, but haven't seen a polished heat sink yet.

    The IGBTs in the photo exploded due to a crowbar failure, but the heat sink surface standard can be seen ...

    50W COB 30V-36V LED minitest from China - will it really be 50W?
  • #18
    GanzConrad
    Level 23  
    p.kaczmarek2 wrote:
    You haven't read the topic,

    I read it, we just have a different definition of a test, or a "minitest". For me, the LED test should go beyond checking if the LED is a good resistor on short run. In the above "mini-letter" you did not answer even the most obvious question, that is:
    Is it worth buying this COB for $ 2? - and more specifically by asking the question:
    Does it have a good enough price / quality ratio?
    I will answer you, not on the basis of the above test, but on the basis of my own tests and experience: It is not worth it, because:
    - a properly matched heat sink will be many times more expensive than this LED (minimum PLN 30 + shipping), i.e. one that will keep the temperature of the PN connector below 85 degrees (you can "gently" assume that it will not burn).
    - in addition, a 50W DC power supply is another several dozen zlotys (I'm talking about the domestic one)
    - some housing could be used ...
    - man-hours
    Bearing in mind the above, I believe that it is better to build lighting based on more expensive solutions (eg COB Citizen). We then gain the quality of light (CRI), much greater efficiency (less heat = smaller heat sink). Workmanship and durability.

    zgierzman wrote:
    I would not go to extremes.

    In this case, it would indeed be an inflection ;-)
  • #19
    pawlik118
    Level 27  
    I think that in many applications of this type it is worth bearing in mind the CRI parameter, which is still often overlooked. If the CRI is bad (let's say below 80) then even with a lot of lm or lx, the feeling will be that "in this light you can't see anything". The poor CRI is due to the fact that the spectrum of light is mostly blue and a little red. Through it we see almost monochrome objects. The second thing is the glare effect - if the light source is punctual, it hurts the eyes. These two aspects make "modern" LED floodlights poorly illuminate the area, unfortunately. Currently, even for home use, it is very difficult to buy LED bulbs with a CRI of at least 95 or 97. Let's be aware and choose good light sources out of respect for our health and comfort of life.
  • #20
    Przybyłek
    Level 12  
    I would like to describe two problems that are raised in this thread, but there is no clear answer.

    The first is the power from the test, I bought a 50W led street lamp 3 weeks ago and yes it has a nice top shape as a heat sink, but it is slightly warm and I think it has a smaller heat dissipation surface than the heat sink in the first photo. Led consumes 50W yes, but how much heat does it emit? Maybe 50% or more, unfortunately this parameter is quite important but I don't know how to easily measure it at home. Maybe some water cooling 10l of water in the circuit, good insulation and check how the temperature rises over time and calculate it?

    The second problem, not related to the diode itself, is the installation in the DLP. Unfortunately, but it makes no sense. About 10 years ago I tested this solution in 3LED and I was wondering why everything heats up more than with xenon and the light is 10 times less. Back then I didn't understand it until the end, the better results were when replacing the original filament with metalhalogen filaments, but it's not the same. After a few years, I understood that, the filament in the projectors is short arc, i.e. the electrode gap is very small, so that the light source is very small and it is easy to enlarge it evenly, focus it into a parallel beam, pass it through the entire matrix system and into the lens where it is enlarged on the wall. With COB, we actually have several dozen LEDs in one housing, so as many as LEDs would have to be also lenses, each of each LED would make a parallel source, i.e. a completely different optics. With the MH filament, the arc is long, but it is less focused than in the short-arc filament (UHP?), So that the light hits the optics less than with the original one, but more than from such a COB LED.
  • #21
    Joker.
    Level 31  
    This cheap Chinese led 4700lm / 50W is 94lm / W. This is so in comparison to more expensive branded LEDs reaching up to 200lm / W. But you know, not everywhere has to be super quality.

    On Wikipedia
    "The luminous efficacy can also be given for an ideal source (683 lm / W) that converts all electricity into light"
    - it comes out that from this Chinese 50W led, 43 watts goes warm. And from such a better 50W LED with a capacity of 200lm / W, 35W will be converted into heat.
  • #22
    Andrzej Ch.
    Level 30  
    I will join the topic because for several years I have been using a COB 50W lamp purchased on one of the Polish auction sites outside a free-standing garage. The new lamp lasted about 2-3 years, then the LEDs started to burn out and I had to replace the COB module with a new one. I ordered 3-4 50W COB LED modules on a foreign auction site. As it turned out, I received 3 out of 4 modules on a very thin plate, and only one of the modules on an aluminum plate with the same thickness as the COB module in the lamp. At that time, I have already replaced two COB modules and I will say yes, in my case the thickness of the COB primer does not matter, it is important to distribute the thermal paste properly. Nevertheless, the COB LED which was installed "at the factory" in my lamp withstood around 200% of the working time of the purchased COB LED "refills".
  • #23
    lopr_pol
    Level 23  
    Just if you want cheap, you have to divide Chinese watts into two. You buy 50W you use for 20-25W and it will be forever.
  • #24
    teskot
    Level 33  
    Regarding the durability of Chinese COB 50W, I can share my observations and specific figures. Factory floodlights of this power operated for a maximum of about 1.5 years for an average of 10 hours a day. This shows how easy it is to count 365 days x 1.5 years x 10 hours = 5475 hours of lighting. Poorly. I took matters into my own hands because replacing lamps was troublesome due to the height of the assembly and the passageway running along. I bought 2 Chinese 100W floodlights, each with 2 COBs. By default, the housing made of some aluminum alloy (ZnAl?) Was to serve as a heat sink. First, it was quite thin, secondly, it was uneven and porous. The conversion consisted in mounting the modules on a polished 4mm aluminum plate, the size of a "tray" of the housing. Only this plate is screwed to the, if possible, aligned housing. Of course, between COB and the board, a decent 3.4W / mK thermally conductive paste. The original driver is dismissed, a new one is built (the more that the lamps are powered by 24VAC, which is worse for trade). I set the maximum power of 18W for one module, which gives 36W all, I added a 50 ° C spring-back thermostat just in case.

    Conclusions:
    -lamps have been working flawlessly for almost 3 years
    -the amount of light (I can't measure it, I rely on my own feeling) is only about 30% less than in the original
    - the temperature of the aluminum plate measured at an ambient temperature of 26 ° C stabilizes at 38 ° C
  • #25
    alt11
    Level 8  
    speedy9 wrote:
    zgierzman wrote:
    I mounted three pieces on a huge heat sink, about 30 x 50 centimeters removed

    The question is whether such a heat sink was suitable. You did not write anything about its shape, but for LEDs, a smaller surface radiator will be better, but a "thicker" one with numerous ribs. In my opinion, the CPU cooler will be better. It is important that it is properly selected, because an ordinary "box" CPU from 45W may not be enough.


    ... two years ago I did something like 2x50W - warm and cold ...


    ... the heat sink is warm at most ... behind the grilles there is a small power supply for the fan, a bridge and about 1000 uF / 400V and a very simple dimmer on a triac. The modules are powered by reduced DC voltage (experimentally set) - this eliminates the disadvantage of these modules - 100Hz flicker. However, at the moment I would give a dimmer with power compensation - it shines unevenly with power surges.
  • #26
    PPK
    Level 27  
    LED COB RGB 10W. For 30W, the cooling turned out to be too weak. Inside there are 2 16850 batteries with protection + 12 V step-up.
    50W COB 30V-36V LED minitest from China - will it really be 50W? 50W COB 30V-36V LED minitest from China - will it really be 50W?
  • #27
    E8600
    Level 39  
    How much time does it shine? Do you have power controls in it? I put together something similar and come to the conclusion that 2x18650 is not enough.
  • #28
    CMS
    Administrator of HydePark
    A small correction to the projectors.

    1. There is no "xenon" in the projector. About the most frequently used burners (the word filament was mentioned somewhere, but nothing glows there), I suggest reading my very old article .

    2. In 99.99% of projector models, the lamp has no communication with either the ballast or the projector motherboard. In rare cases, an integrated circuit containing an hour meter is installed in the lamp module.

    3. Tricking the projector to "think" that the lamp is on and working properly, there is a short circuit of the "return" optocoupler in the ballast module or on the motherboard. The problem may be the moment of the short circuit. Sometimes it is enough to make the jumper permanently and already, but often it is required that the closure of the optocoupler circuit is at the right moment. What can be determined experimentally.

    4. Converting a DLP projector to a COB is practically impossible. Unless you manage to focus all the light at a point of about 5x6mm. Of course it is theoretically possible, but count / imagine the dimensions of the lens / mirror.

    5. With an LCD projector, such a modification has a high chance of success, especially if we have an older projector model and the "multi-lens" in the lamp chamber will have the same or slightly larger dimension than the COB surface.

    However, a serious problem remains, even two. The original lamp in the projector "gives" 20,000 - 30,000 thousand lumens, as it relates to such a COB. The second problem is CRI. The projector lamp has this coefficient of up to 97-98, while the COB is up to 90 ...

    PS.

    Somewhere else the slogan UHP was mentioned, also used in the wrong context.

    For example, UHP is an abbreviation for Ultra High Performance - it is used by OSRAM., UHB is Ultra High Brightness - this abbreviation is used by Philips, but it is the same AC burner.

    Someone also wrote about the short bow, probably the same colleague from UHP. This is the key to focusing the light on an ORIGINAL reflector / mirror. And then direct the light beam accordingly. Depending on whether the lamp is to work in an LCD or DLP projector. Regardless of the technology of the projector, the electric arc, which is the light source in the lamp, is 1-1.5 mm long and generates the previously mentioned tens of thousands of lumens. Imagine a lightning bolt closed in such a tiny bubble ...
    I have already mentioned that the pressure inside the burner during operation is from 300 to over 1000 BAR.
  • #29
    PPK
    Level 27  
    E8600 wrote:
    How much time does it shine? Do you have power controls in it? I put together something similar and come to the conclusion that 2x18650 is not enough.

    I didn't really live with this COB. Currents acc. factory data is 0.3A for 6V -R, 9-12V - G, 9-12V - B. I gave 0.25A but by selecting resistors because there was not enough space for current stabilization of each channel. Switching colors and sequences on some old RGB strip driver. As it was just a project, I tested it for 3-4 hours. One charge was enough for about 60 minutes of correct operation - 16850 from recovery, but the tensions remain. I also tried to do 4 batteries, but there would be no room for anything else inside the heat sink. Now I will test RGB 30W (approx. 20-30V; 350mA) but on a different heat sink and with the original three-channel RGB strip driver (conversion of the end MOSFETs to a higher voltage).
    ps There in the middle under the glass, there was also a reflector / reflector properly trimmed, overlapping the COB.
  • #30
    artbi881
    Level 17  
    Hello, everything is great, but no one has tried to measure the amount of light that these leds produce, the cheapest "lux meter" can already be purchased for PLN 30 from a Chinese, I think there will be poor results with this amount of light, question what such a cob contraption that gives little light and a lot of heat ordinary light bulb is almost the same :) only RA is better and what Lux / Wat looks like
    50W COB 30V-36V LED minitest from China - will it really be 50W?