DIY 100W Bulb Using Chinese LED Chip (CAREFUL)




Introduction: DIY 100W Bulb Using Chinese LED Chip (CAREFUL)

Hello friends!

First to say (as you will see in the video comparison) The LED chips from china are not real wattage. So be careful to loose the time and money. Make sure to buy a real 100W chip from china or elsewhere.

Watch the video for more details:

links to the equipments I used:
LED chip:

Step-down module:



Step 1: How It's Done..

Connect the cables from the base to the LED chip and connect them also to the input of the step-down module and make sure of the polarity.

control the output of the step-down so it gives 12v output then connect it's output to the fan and make sure of the polarity.

For more safety, put a diode before both the LED chip and the step-down module.

Any question just drop a comment.

Happy making!

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    5 years ago


    Did you measure the voltage over and current through the bare LED chip when it is on? I'm wondering if your setup smothers the LED a bit, with the low reading and low light

    Another possible reason for the apparently lower output compared to the 50W "bulb" might be a difference in color temperature - warmer whites has less output than the neutral whites, with cold (bluish) white having the highest output, which makes it a puzzle that they make work lights in (very) warm white (bought a 30W and a 10W to use for photography, but unfortunately they're around 3'000..3500K).

    Have a nice day :)

    Rajaa Kahel
    Rajaa Kahel

    Reply 5 years ago

    Here you go!
    The color temperature is almost the same about 6000K you can notice the colors..
    I understand you.. But I don't think this is the case here..
    So what do you think with the readings? BTW the supply is 35.6v


    Reply 5 years ago

    The 32.9V @ 1.6A (52.64W) makes me wonder if they just sold you a 50W LED (however they marked it).

    The numbers in the photos of your DMMs equates to ~31W and in your last note you mention 35.6V (but without the current)

    The thing is, they set a very wide voltage range. It seems like there is 10x10 LEDs in the array, which gives 3.0V to 3.6V over each (row of 10 parallel individual chips).

    It's too bad that there's no datasheet, as this sounds strange - the voltage drop of LEDs are defined/measured at their nominal current and this large a span will mean that at the lower end they'll last longer and v.v. just not possible to tell how much shorter it will be at the high voltage.

    According to the (much too little) data from the seller, you feed them 3A and that should result in a 30..36V drop. I hope you're aware that LEDs are current driven devices,which means that, theoretically, a 50V (or whatever) supply could be used, as long as the current is limited to 3.00A.

    I won't try to lure you into destroying your LED, but given the price, I wouldn't be surprised if you got a few extras and if, you might consider a possibly destructive test, by feeding one of them 3A (if you have a current limiter of sorts) and see what happens (measuring the voltage drop over the LED concurrently).

    If you control the voltage alone, there will be a huge difference from 30V to 36V (and as it heats up, the voltage drop will shift - perhaps to more than it can handle.

    Just from the top of my head. Let me know if you have any specific questions or you want a more in-dept answer - If needed, I can draw you a 3A current limiter.


    Omnivent (Copenhagen)

    Rajaa Kahel
    Rajaa Kahel

    Reply 5 years ago

    Hello again! First of all, have a nice day (because I forgot to say it haha)

    Well, This LED is 10X10 array, but say it's 50W according to the numbers we got, still not brighter than the 20W LED lamp! So how can you explain this?

    I don't mind burning the chip for a test, So I ordered a little lab power supply to give it exactly 36V 3A or so.. this one:

    It will be here in Sweden in a few days so I can make the test very accurate.

    Thanks for the offer neighbor, but I will save you for later if you don't mind, because I love electronics and I don't have so much knowledge about them so I always have questions.. (I always wanted to marry a woman who loves electronics with no luck).



    Reply 5 years ago

    ...And when I was almost done with this post... Arrrgh computers ;)

    Rebuilding from memory...

    Nice supply!

    When you are ready to test, here's the MO (and with that supply, you have the current limiter you need):

    Turn on supply

    Turn down (CCW) current controls (both coarse and fine)

    Set voltage to 38..40V

    Connect LED chip (this will make the voltage plunge to around 0V)

    Gradually increase current from 0 to 3.0A (keep the cooling fan running)

    If the voltage at any time raise above 36V, abort mission

    If it turns into a fireball or behaves strange, abort mission

    It will be a good idea to keep your DMMs in circuit, as they're bound to be more precise than the V/A-displays in the supply.

    I thought the LED lamp you compared to was 50W(?) if it's only 20W, I have no immediate explanation, but I guess that you're aware that we have a logarithmic(-ish) eye response, so small differences/steps takes increasingly larger levels of power. Then there's the spread of light - does the "reference"-lamp have the same radiation angle(?)

    And then there's the Chinese factor - they tend to be very optimistic with their data (to be polite and not call them scammers ;))

    Looking forward to hear about your findings - don't hurt/burn yourself on anything :)

    Just send me a PM if you have questions about something else, at any time in the future!

    Don't long for a woman into electronics - she'll just use all your components ;) Besides, all of the (very few) electronics apt persons of the female persuasion I've ever been face to face with have been nerdy, needy and no good - and further, you grow more with a person that's not too similar to yourself.

    But it would be nice to be able to talk tech with them wimmin' of course and if we could convince them on the difference between clutter and highly abstraction levels in component and material selection, we'd take less flak :D

    Have a nice day neighbor :)

    Rajaa Kahel
    Rajaa Kahel

    Reply 5 years ago

    Oh, yeah computers..

    I'll test it the way you suggested and will post the results.

    The 20W lamp uses SMD5730 I don't know exactly it's radiation angle. But the 100W chip is 120 degrees.

    Yes, I know that LEDs can draw much more current suddenly when you reach a certain voltage value (so it gets burned if you don't have a current limiter).

    Thanks I'll send you a message when ever I need a help :D

    Looks like you are an expert with lot of stuff Haha.

    So I'll stay satisfied with what I have and will keep a shield! :P

    Rajaa Kahel
    Rajaa Kahel

    Reply 5 years ago

    I raised the voltage on the power supply to 40v in open circuit so it's 32,9v in the closed circuit with only the LED. The current jumped to 1.6A. The brightness increased just a little bit..

    Rajaa Kahel
    Rajaa Kahel

    Reply 5 years ago

    Looks like the photo is not uploading