Let's talk DIY lights


#1584

When I told @TDubWilly I was going to wait until my grow finished before installing my new lights, he said, “Why? Would you not put them in the sun if you could?”

So… I installed them this morning!

Only dropped a driver on a plant twice too.


#1585

Nice really nice


#1586

I’m not gonna lie, was kind of thinking the same as @TDubWilly. But figured I’ve given you enough bad ideas lol. Better to let him take this one. It looks great!

How do you feel coverage and everything is with the three bars?


#1587

I think the coverage will be perfect. I’ll be orienting them the other way for the next grow but due to how the tent is currently set up I couldn’t do that right now. For now it should be fine. Sure is nice to look at without the blurple!


#1588

Glad you’re digging them @Bogleg . I’d kind of feel like a jackass if you weren’t happy.


#1589

Well, we’ll see how they work on the next grow and then I can determine if you are a jackass or not.

Just kidding! I’m super happy with how they look. I am probably just as anxious to finish this grow for the weed as I am for the opportunity to tweak and perfect my wiring.


#1590

One of things I am going to do before I start the next grow is put WiFi enabled switches on the lights. Once I perfect building them on a regular power cord I will install them on the lights. I am going to use a buck converter to convert the incoming current down to 5v to power the relay and little WiFi card. I got some small junction boxes I am going to use to house the electronics. Then I will be able to turn the lights on and off from anywhere. After that I’ll look into dimming options.


#1591

Hahaha, all good! I have big shoulders, can take a little abuse.


#1592

Not necessarily 45min :joy:… After 15min is :fire:… Need to install a fan :triumph:


#1593

Definitely if that’s the case.


#1594

The temperature is 150F. I don’t know if the meter is good but this I have in hand (even meter)


#1595

Surprisingly enough, 150f is within safe operation range on most leds. Not say your led is same temp as heatsink though. Get some air moving over it and should be good.


#1596

Good to know that :+1:. I forgot where I put my bag whit small fans :joy:


#1597

Even a small and quiet fan will make a huge difference and hardly cost anything to run. Heat sink performance goes up by about a factor of 4X when you run a little air through it. Nice you have a bag of fans.

For those of you that don’t: Electronic Goldmine has a large assortment for 5-10 dollars each.


#1598

While fans help, I don’t think it’s completely accurate to say they will help 4x. If I put a fan blowing directly on the bar stock my strips are mounted to it lowers the measured temp on the bar stock a few degrees at best. With 1-2 degrees Fahrenheit lower measured on case temps. That’s not enough to justify running a fan on them.

In a different scenario where the case temps and sink temps are running more than twice the ambient atmosphere temps, the difference will be more significant. But even my cobs that usually measure around 40-50c, no fan is going to drop that to even 25c.


#1599

True, a fan won’t make that much difference on bar stock. But when you have a bunch of fins close together, a fan will continuously change the air next to the fins with new room temperature air. Without the fan, the air between fins may get to a much higher temperature so much less heat transfer occurs. If you can orient the fins vertically, convection will be your friend. Unfortunately, for our case most fins will be horizontal so very little air moves through them. That 4x figure is from several engineering papers about active versus passive heat sinks.

Pin-style heat sinks are designed for running without fans. Microprocessor heat sinks with their tiny gaps between fins ARE designed for fans.


#1600

I understand what you’re saying, but we’re not building microprocessors either.

I have linear extrusion heatsinks that I can guarantee a fan won’t drop 2x let alone 4x. It has very little to do with the style of heatsink, and a little to do with the spacing on fins, pins, or whatever else is used. And just about everything to do with how the heatsink is loaded.

We were responding to @M4ur light right? It’s the perfect example in my opinion. To reduce 150f x4 that means a fan will drop that to 35f. Ain’t happening bro.

I’m sure if we loaded a small enough heatsink up thermally a fan could show results in that neighborhood. And in engineer lingo, they would be correct. But those numbers aren’t realistic for us in our typical everyday uses.


#1601

You need to factor in the thermal mass, heat load, thermal capacity, ambient temperature etc. Air is a poor conductor for sure but 4X efficiency to me wouldn’t mean a 4X drop in temperature but the ability to handle 4X the heat rejection. That’s where finned heatsinks will perform as a simple function of more surface area.


#1602

In a past life I was an engineer that specialized in military infrared systems which are all very concerned with heat load and power dissipation when cooling to 65°K. I’ve worked on everything from cryostats to Stirling cycle, split Stirling cryopumps to a Dewar full of He.


#1603

Exactly, performance going up is subjective. Under different circumstances, people would think you’re crazy for using the cheap thermal tape to put that much power on rectangle tubing. But how’s it working? They put efficient enough leds on a decent pcb and the rest is history.