LED Light Design and Build Diary

[putt4dough]

How'd this progress?

 

 

It's still a work in progress, though I've changed the design a fair bit. I did some tests on the extrusion and, although it was a good heat sink, it was too heavy to be practical. 

 

I went back to the drawing board and have decided to go with a stripped down flat design (image attached). The idea of the updated design is simplicity. I've tried to keep the same spectrum as discussed earlier, but I've lowered the LED count and spread them out for good heat dissipation. This also gives an improved light spread. The LED panel now measures 460 x 460 and will deliver around 220W. This should be perfect for my 60 x 60 cm tent and I've added mounting holes to mount more of these on a frame for a bigger tent. I've also moved the power supply away from the LED heat sinking surface.

 

As before, I'm still planning to use Cree XLamp XP-G3 LEDs in white, red and blue.

 

Basically, all I want in this light is a good spectrum, high quality LEDs and a solid power supply. If I can leverage my engineering skills to get that cheaply, I'll be happy. 

 

It's a slow moving project but I'll keep posting updates.

[putt4dough]

I've made a bit more progress on the light design I've been working on. I ordered a PCB to be made to the specs I've mentioned above and it arrived this week (images attached). It's EXTREMELY bright!

 

The idea was a large PCB surface area to allow heat dissipation without a fan or heatsink. After some testing, unfortunately that's not going to work.   The LEDs are pulling 214.6W which heats up the board to around 40 deg C above ambient which was too hot to touch in a 25 deg C tent. In the height of summer I can see the board temperature going extreme. I retested the board with a single 120mm fan and it only really gets to around 10 deg C above ambient. Much better.

 

The next step is to rejig the design (once again) to incorporate fans and a dimmer knob to turn down the eye burning light when inspecting plants, etc. Attached is an image of a simple cover design with fans and a dimmer using laser cut aluminium sheet. 

 

If anyone's interested I'll keep posting updates.

Edited December 12, 2019 by putt4dough

[gazza308]

Yeah mate I’m interested, keep going.

[putt4dough]

Some more progress has been made on my light project. Earlier this week I received the sheet metal cover and Thursday I assembled the light with four 80mm fans. Yesterday I put the light in my 60 x 60 tent and gave it a good torture test. It got to 43.9 deg C at my house yesterday, and I ran the light all day without a problem. The highest temperature the light got to was 52 deg C, which was slightly uncomfortable to the touch but not at all dangerous.

 

Attached are photos of the light in my tent, one trying to capture the colour of the light and another of the spectrum of the light being split by the half open door of my tent.

 

Overall I'm happy with the light, though there are some changes that I would make if I decide to iterate the design again. The first issue is the fans. Compared to my old light, which was passively cooled, the fans on this sound like a light plane taking off. This isn't really a problem given that I also run a fan in the tent and an external exhaust fan, but it's just another source of noise. Secondly, the Cree XP-G3 LEDs are extremely fragile. The "lenses" on the LED chips are made of a material like silicone rubber and it I bumped one it would come off for sure. In an updated design I would add secondary lenses for protection.

 

The next step is to grow under the light to see how it goes. I would love to do some PPFD measurements but I can't justify the expense of a decent sensor given this is a hobby project. I'll probably do some more design work to see if I could produce this light without the fans (i.e. some proper calculations, simulations, etc.) but I don't know if I'll actually build it.

[ooodog]

Good on ya for having a crack. Plz keep posting updates. I thought it was bad manners having the Mars rep in your thread trying to flog their lights. Very rude.

 

 

Sent from my iPhone using OZ Stoners

[Porky 1982]

Nice work.[emoji106][emoji106] Keen to see some plants under it.

 

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[MongyMan]

...... I thought it was bad manners having the Mars rep in your thread trying to flog their lights. Very rude.

 

 

Yes I agree. Mars spam posts deleted.

 

[putt4dough]

Good on ya for having a crack. Plz keep posting updates. I thought it was bad manners having the Mars rep in your thread trying to flog their lights. Very rude.

 

 

Sent from my iPhone using OZ Stoners

 

Thanks ooodog. I'll post some updates once I have a couple of plants established under the light. I've also been playing around with heatsink simulations so I might post a bit on those as well. It's probably boring technical stuff but maybe someone else is interested.

[ooodog]

Thanks ooodog. I'll post some updates once I have a couple of plants established under the light. I've also been playing around with heatsink simulations so I might post a bit on those as well. It's probably boring technical stuff but maybe someone else is interested.

post away. For the bits I don’t get I’ll just smile n nod [emoji16]

 

 

 

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Yes I agree. Mars spam posts deleted.

 

thx mongy

 

 

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[Frank Reynolds]

Very interesting thread!

 

I have to say a few years ago I did not think LEDs were even close enough to HID etc, but after seeing these DIY boards it's quite impressive. These DIY ones don't seem crazy hard to set up, why is it commercial LED's seem to lack behind?

Edited December 23, 2019 by Frank Reynolds