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QLD Arenas
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Nick
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There is no space for vents - its all LED strip or wooden sides. The lights don't really heat up in less than 5 to 10 minutes so either someone pulls the plug out, or I get this DMX board wired into a case.

Once I get the lights and a smoke machine switched with DMX, we will probably have the most advanced arena lighting outside of the Battlebots studio. Smile
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Post Mon Sep 07, 2015 9:26 pm 
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marto
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It seems the heat is in the LEDs. not really spreading out. An slightly thicker strip of Ali under them might be enough to help dissipate it.

Steve
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Post Mon Sep 07, 2015 10:09 pm 
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Nick
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The cooler part of the photo is the wooden sides on the light fitting - the aluminium back panel goes the full width and its fairly evenly hot across its width. I was hoping that 1,650 square CM of aluminium back plate would be enough heatsink but maybe not...

If I can find some U channel for the remaining lights, I will add that and like Miles said, its easy enough to just turn them off.
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Post Mon Sep 07, 2015 10:18 pm 
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Knightrous
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Are these strips and drivers compatible with the LED dimming circuits? If so, you might be able to dim them to 50% power in between matches and then crank them back up during the fight.
Could potentially automate it with your arena controls.
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Post Mon Sep 07, 2015 10:47 pm 
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Nick
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I don't think the power supplies are compatible with PWM dimmers. They don't mention PWM at all but I remember a LED dimmer project from Silicon Chip, where they mentioned that tests with PWM and a constant current LED supply like mine resulted in a melt-down.

Dimming would be the ultimate but I would probably have to make a bulky linear PSU for dimming to work. Perhaps that is something for next year; I could make a large central PSU and dimmer with low voltage leads to the lights. The other thing I would like to try is a high power white light with two lower powered colours down the middle (ie UV and amber). There are cheap 3 channel PWM controllers that will let the lights be faded from white to a funky twilight colour. If you have flown Virgin, I'm thinking something like that.
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Post Mon Sep 07, 2015 11:05 pm 
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marto
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It won't be DMX compatible but TZ85As will do the trick. If there is an arduini DMX sketch then can drive all of them from that.

Steve
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Post Mon Sep 07, 2015 11:24 pm 
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Nick
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Won't the TZ85A PWM still potentially screw the power supplies? Would adding a crapload of capacitance smooth out the PWM into an average voltage? I wouldn't mind trying it, but if I fry a PSU before the event, its too late to replace it.
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Post Mon Sep 07, 2015 11:32 pm 
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miles&Jules
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what if the lights were just up off the poly carb a bit more? then they wouldn't melt the roof or are you worried that the lights them selves will burn out from heat?
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Post Tue Sep 08, 2015 12:13 am 
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Nick
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Only the LEDs and the aluminium get hot - the sides are 30mm high and the plastic on the front isn't likely to get more than warm. 60 deg. is not that fatal in the short term but I want the lights to be as reliable as possible for as long as possible.

UPDATE:

I just found a spec sheet for the LEDs and the maximum operating temp is 85 Deg. C, so 60 is high but far from critical. Just switching the lights off between matches will be fine.
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Post Tue Sep 08, 2015 12:41 am 
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miles&Jules
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cool…the hardest bit will be remembering to turn em back on i guess
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Post Tue Sep 08, 2015 12:46 am 
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Nick
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That's easy - if you aren't squinting, you need to turn the lights on! Laughing
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Post Tue Sep 08, 2015 12:53 am 
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marto
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Should be fine its no real different than running a battery charger or something else which uses PWM.

Steve
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Post Tue Sep 08, 2015 9:42 am 
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Nick
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OK, I can use the existing FET circuit from the arena display to PWM the LED strips before I finish assembly. If that works, then I can add DMX dimming to the lights later on using an off-the-shelf module.

I will add some heatsinking to the back of the remaining lights like this:



Two 25 x 25mm U channels more than doubles the area of the heatsink and should let the lights run full time without serious problems.

I like these lights so much that after the event I want to make a set for the workshop and they will need to run all day in summer temperatures, so testing the arena lights with extra cooling makes sense.
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Post Tue Sep 08, 2015 10:38 am 
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miles&Jules
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what do they have on the back of those leds is it plastic or metal? I got a big ass 10watt one in my film transfer machine. its got a metal back and it died after a month- i think cause i didn't have that thermal paste stuff on the back to transfer the heat.
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Post Tue Sep 08, 2015 11:02 am 
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Nick
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The strips are made of flexible circuit board with thin double sided tape on the back. The individual LEDs a not high power but with so many packed in they get toasty. When I put the C channels on I will try to use heat transfer paste.
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Post Tue Sep 08, 2015 11:13 am 
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