COB LED

Discussion in 'Anything DIY related' started by f-fish, May 11, 2018.

  1. Beachless

    Beachless

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    These things are notorious for having mismatched LEDs and shorts or low resistance paths across them. I think many of the ones we buy were thrown out by the manufacturers and that's why they are cheap.
    If you have a variable power supply and you take the voltage up from zero you will see some LEDs and rows lighting up before others and some LEDs starting up very slowly. That's why they are generally so inefficient.
    A good led matrix like this should have all the LEDs matched closely with each other to be efficient.
     
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  3. OP
    f-fish

    f-fish #unspecified

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    Agreed - that is why I have typically stayed away from COB units ... had some back experiences when they first hit the market, but for this price and amount of DIY fun, it is hard to go wrong.

    I think I need to revise my inefficient concern - it was more wasted heat but as this type of lm/watt for grow lights ... so what if you get a room heater at the same time ;-)


    Later Ferdie
     
  4. Beachless

    Beachless

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    With them being so cheap its easy to treat them as consumables and replace them when they fail. (More playing around is also then possible :) ). I went with the smaller 10w ones as they have less LEDs per row so hoping have less issues and I will just add more of them to add more wattage. The heat can be useful for early morning in the winter :)

    From your measurements it looks like they put out a lot of usable light. Have you measured how quickly it drops off towards the sides off center?
     
  5. OP
    f-fish

    f-fish #unspecified

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    No because I do not have a underwater meter ... angle, refraction absorption all of that comes into play - so my standard for performance comparison is one net plant spacer away from the source looking for the best possible amount of light.

    I have some 10Watt COB's somewhere ... - think they are 12 volt...
     
  6. OP
    f-fish

    f-fish #unspecified

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  7. Beachless

    Beachless

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    Would be cool to know if the 10w is 1/3 or the light of the 30w.
     
  8. OP
    f-fish

    f-fish #unspecified

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    Ok found them ... I did not realize that they are full spectrum till I went back and looked at the order ;-) Thanks for the prompt ...

    e7mv0vKOyH8ZomLEIWtoOv5BjPwrgKnHaEQzf5K5jA8TFxr2AmOh555x6OS8_mBClslMT_S5GkIv2p6gQ=w2200-h1241-no.jpg

    Actually - now that I have some thermal paste I really should see what it would take to get these going.

    And this just when I thought my 12 volt days are over ;-)

    Later Ferdie
     
  9. Barry Roux

    Barry Roux

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    I normally use these no fans just drop the voltage to 10v and they go forever
     
  10. Beachless

    Beachless

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    I'll keep an eye out for the post :thumbup:
     
  11. Beachless

    Beachless

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    You have any pics of your setup?
     
  12. OP
    f-fish

    f-fish #unspecified

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    These 10 Watt chips are crazy ... ok so it is not the best power supply .. actually I would recommend you do a constant voltage supply cause these chips will draw the life out of your supply.

    unI2GqDBcUF49ODBrbfj3BEUPj5IqKlZeAtPthbJvX9MPBaIMREWRQyMy0ccNC9nXZmtIFKfuTaR2FK0g=w2200-h1241-no.jpg

    they seem to have allot more white in them .. still red and blue but loads of white also.

    _tl3SWbxvb22PoIgXp5BwmO600AOYhOg0ypBdgSNGR-O0GGltspIsvuvwvDABTET26Eu6_eYftmSC178w=w2200-h1241-no.jpg

    but it is a monster chip for its size... 10 watt no way, more like 14 watt

    0R6jNieUHzWXxBiamEeXLUEi-h0HLGWXlnzalee1SDRIJVqKOw7E428oPR1_kjkxAB7xkrvAm5jOJYe3A=w2200-h1241-no.jpg

    but here is the kicker ... with all that extra white

    Mk6p2roTLt8D_989bpgBZempkAexBePisoOIbVqVKWctpk3fHD-9nbuLSdkcYdm_ciuljflU56sgWzg9Q=w2200-h1241-no.jpg

    the lux meter is loving this chip to the point that I do not trust this reading ...

    TTjmgZ96gpI2Qdv-duNbnytUzeNWpPufJPNp-_qi44Xib9cS8SFxS0R5ECt3ARW3r7elYDfjHYwn_x-mw=w1687-h1265-no.jpg

    That said - even with my superior engineering on the 1 meter long H-bar and Z5 thermal paste .. the chip very quickly got to a point that I could not touch it or the bar near the point.

    bztBEujKMoCK2q_A5NnkIuSDip2s41kUZGyp5BVDYnTBuPfS4w-WwiPyqq99sgMU8mTyEQak7Fd9vxAdxw=w714-h1265-no.jpg
    Will still play with these a bit more - they do seem like fun with loads and loads of light. Maybe another CPU heatsink will do the job.

    @Barry Roux think it is a smart thing to limit these on the DC side ... they are killer.

    Later Ferdie
     
  13. Beachless

    Beachless

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    That was quick :eek:

    I suspect these are very directional that's why you are seeing the high lux readings.

    I run a 5w 12v cob on my printer for lighting and fitted a 80 ohm (can't remember exactly) 5w resistor and it took care of all the heating isssue. So I definitely agree that they need some sort of current limiting.
     
  14. OP
    f-fish

    f-fish #unspecified

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    Yeah the 10 watt COB seems a bit more dense than the 30 Watt version ... and the extra white plays to the human eye and what the lux meter reads.

    Still was fun to try ... but will not leave this as a light source just yet. Need way better thermal and power control.

    Later Ferdie
     
  15. Beachless

    Beachless

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    I agree I think a proper driver will make all the difference.
     
  16. Blade

    Blade

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    Added a 2.2ohm resistor to limit the current, current generates the heat cause led just draws whats avaliable. I run these 10w leds with resistors on each and temp dropped by half.

    Sent from my SM-G930F using Tapatalk
     
  17. OP
    f-fish

    f-fish #unspecified

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    Thanks @Blade ... I only have 1/4 watt resistors on-hand so will have to go do some component shopping - oh dear ;-)
     
  18. Beachless

    Beachless

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    Just be aware that you can still get thermal run away with the resistor but its much better than nothing. A regulated supply is the best way to do it.
    That said I'm planning to just do the resistors on mine with some 12v fuses inline.
     
  19. Blade

    Blade

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    Look for at least a 2 watt or higher ressistor. I have 2 x 10w leds mounted on just a cpu heat sink and they run pretty cool even in a closed lid on 3ft tank.
    Sent from my SM-G930F using Tapatalk
     
  20. reuben

    reuben

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    h9zlydci9zl7668uolokx8i3hf_wpqtdlee2k_bystibq7-z6lgbpwulpxwtcoufprspxheoqw6xq-w2010-h1265-no-jpg.jpg

    Hi Ferdi
    Are these watt meters good and where would one get them from

    rgds
     
  21. OP
    f-fish

    f-fish #unspecified

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    Hi Ruben .. this one is a few years old - got them from builders back then now I thin you will only find https://www.ellies.co.za/product-category/renewable-energy/energy-monitoring/ in SA.

    it really is convenient the way I am using it for test and validation ..

    but I use https://www.ellies.co.za/product/efergy-energy-monitor-e2/ for actual house monitoring.

    and https://www.netram.co.za/3641-sonoff-pow-wifi-switch-16a-with-power-consumption-measurement.html for the actual fishroom measurements.

    They all seems to tie up to city power charges at some point.

    PS side note .. the e2 and pow talk back to domoticz that is the pics I post on consumption.

    Later Ferdie
     

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