Can't get cheaper than this

dadums

Well-Known Member
Someone asked if these worked so since I has a CPU heat-sink laying around I bit and got it on Ebay for $2.80
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Very bright
 
Giving this thread a bump as have just made some test lights out of these chips.

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All 50W, "driverless" chips from China off eBay. Wired up to 240V. Built in so output through 98% transmission acrylic.

Made up a 1 chip unit and tried it as a passive heat sink. Within 10 mins the heat sink was at 104 degrees C.

Put a 12v computer fan on it and then maxed out at 36 degrees C.

Found some 240V cooling fans so both these test units use those now. No need for separate 12V supply. :)

1 chip unit runs @ about 42 degrees C now. 3 chip unit @ 35 degrees C. There is no discernible flickering.

light output a bit disappointing.

I did some tests on other LEDS. Best one was a "600W" 2 chip COB LED off the shelf for about AU$180. Draws 110W out of the wall according to specs. Second best a "600W" with about the same 110W draw but multiple "epistar" chips spread out on a panel. tat was about AU$90 off eBay.

All light readings PAR (umoles) @ 30cm below the center of the unit.

"600W" COB 835
"600W' epistar 293
My 1 chip "50W " 124
My 3 chip "150W" 285

So, its on par with the commercial off the shelf "epistar' type.

Cost for parts to build the 3 chip unit? Hard to say as had things like acrylic in the workshop. But, i reckon about AU$60.

Will have to do some further tests. Would like to check the actual power draw and that may take a few days. Maybe they sent me the lower power chips they had advertised?? If that turns out to be the case i will try and get actual 50W from another supplier and rebuild.

That said, the lights look pretty bright. Certainly not useless.
 
Did some test for current draw this morning. Tech down the hall had the right meter to measure amps in real time. :)

So, a=on a watts = Amps x Volts basis.

1 x 50W COB 1 chip Unit Draws 81W
Ambient PAR for test 008 Stable temp 40.8 Degrees C

@ 30cm distance getting 274 umoles PAR.


1 x 150W COB 3 chip Unit Draws 212W
Ambient PAR for test 008 Stable temp 33.8 Degrees C

@ 30cm distance getting 134 umoles PAR.

Mk3 may be done tomorrow.

Thinner acrylic but dont think that will make much difference to light transmission.
2x 80mm 240V cooling fans for redundancy. I think that is needed for safety as if you rely on the passive heat-sink the temp will get very high very fast.

6 x 50 W COB LED's mounted in two groups.

Much more neatly put together.

Expecting a draw of a little under 450W. If i can get that to work with its temp stable at something under 50 degrees C then i think i'll make that my "standard" LED unit and then look at footprint vs intensity and work out how many units to cover an area and at what $.
 
"unfortunately I'm not an electric engineer so don't really have an insight on what might go wrong ."

Me too. :(

One of the units i build blew up yesterday. Hot and tripped the RCD. Think its a fan failure..... but will have a look today and check wiring and the chips. The 240V fans i used are old ones salvaged from other stuff.

Starting to think about looking at combinations of white LED 5630 strips (12V) and using these chips as fill ins??
 
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