DIY COB Bulb 5W-20W under 30V - looking for COB and advice

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Joined: 04/08/2021 - 05:38
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DIY COB Bulb 5W-20W under 30V - looking for COB and advice

Hi, for long time I like to make my trustworthy, efficient DIY “bulb”, FOR ME (so safety, failures, experimentation and adjustments are not concern here ;P).
For many of you know, normal bulbs/leds are over driven, companies reducing live span and electrical deficiency.

My idea is to make is to make:
COB based “bulb” that will +- fit into hole of standard MR16 bulb.
Its cheap to buy used, quality 12V or 18.5V, even 24V PSU. Its hard to get in good price 30+V. 12v3.3A cost like 1$. 24V 7.25A cost 9$.
Id like to use module like this to drive COB:
step down based on XL4015 with current limiter
(btw, does any1 know what is difference between “XL4015 module”, and “Original module” ? I cant find answer for this for quite some time, and many sellers use this two “versions”)

To make cheap cooler/radiator id like to use 1mm aluminum sheet


In some shape like this (it was made just to show concept, final version must be adjusted to used cob and its heating)
I tried this design with so called 30w cob from ali (didnt dare to drive it more than 22W), and it was cooling it to +-43*C constant.

I suppose i cant use noname COB from ali, as diodes can different like hell from diode to diode (couldnt find reliable suplier on ali, who could give data sheet, or even information about binning leds). I plan to drive from one XL4015 module like 2-3 “bulbs”, “lamps”, so diodes must take similar current, as I dont plan on using resistors i think. I also take into consideration to use like 2-3 XL4015 modules conected to one powers supply (in example 12v4a).

For now for tests I ordered 20 Cree CMA1303 0000-000C0U0A40G, but they are quite expensive if id like to buy better CRI/temperature.

Could you please advice me 5W-20W COB from solid manufacturer that share a datasheet, basic reliable info about cobs? Where to get those cobs… Or at least models? I was lookin for samsung, citizen, bridgelux and I cant find any model but those from cree who make COB 5W-20W with under 30v (best Vmax under 12V, 18V or 24V). I supposed if i drive COB with recommended, maximum efficiency lm/W current, those DIY bulbs could last years, and be really power efficient.

I tried to test different cobs from like 15 sellers from ali, but its just a joke, those are damn heaters, not light source. But I have to say, those were almost random no name chips, no idea how to look for solid brands on ali. Could u guys help me to find suitable cobs please?
For now, other parameters are not so important, but like to start from CRI (70+), temperature (lower than 6k) and lm/W 100+, first have to make it working at all and find source of COB.

I am sure you are way more experienced, and maybe you will find some interest.

I can do some test, have osciloscope, decent thermalvision, thermocouple, bench power supply, luxometr.
EVERY advice concerning project is much appreciated.

Edited by: Uber1337 on 04/08/2021 - 13:00