Heatsinks for DIY LED lamps

DoctorDelta9

DoctorDelta9

Well-Known Member
So I'm trying to measure current with my fluke 115. But when I measure. The light loses power. The leads on my meter spark and my mA numbers just cycle and run wild. What am I doing wrong?
 
bicit

bicit

Well-Known Member
DoctorDelta9 said:
So I'm trying to measure current with my fluke 115. But when I measure. The light loses power. The leads on my meter spark and my mA numbers just cycle and run wild. What am I doing wrong?
Click to expand...
Shut down the light, wire the meter in series on the (+) driver output. Connect the (+) terminal of the meter to the (+) lead from the driver, then connect the (-) terminal of the multimeter to the (+) input on the LED and finally the (-) output of the LED to the [-] lead from the driver.

When measuring the current, the power needs to flow through the meter in order to get a reading. The internal resistance of the meter is rather high, by design. So if you have a wire leading from the [+] led of the driver to the [+] impute of the LED in addition to the multi-meter, you've effectively created two parallel paths for the power to travel. In which case it's going to choose the path of least resistance and you won't get a proper reading.

Someone else may have some corrections to this. Or better wording.
 
DoctorDelta9

DoctorDelta9

Well-Known Member
bicit said:
Shut down the light, wire the meter in series on the (+) driver output. Connect the (+) terminal of the meter to the (+) lead from the driver, then connect the (-) terminal of the multimeter to the (+) input on the LED and finally the (-) output of the LED to the [-] lead from the driver.

When measuring the current, the power needs to flow through the meter in order to get a reading. The internal resistance of the meter is rather high, by design. So if you have a wire leading from the [+] led of the driver to the [+] impute of the LED in addition to the multi-meter, you've effectively created two parallel paths for the power to travel. In which case it's going to choose the path of least resistance and you won't get a proper reading.

Someone else may have some corrections to this. Or better wording.
Click to expand...
Yep I was doing it all wrong. Thanks for the education!
 
SupraSPL

SupraSPL

Well-Known Member
DoctorDelta9 said:
So I'm trying to measure current with my fluke 115. But when I measure. The light loses power. The leads on my meter spark and my mA numbers just cycle and run wild. What am I doing wrong?
Click to expand...
Are you aiming to measure the current on the DC side? There is a separate setting for AC and DC. Also the red lead has to be plugged into the "10A fused" slot. If you are getting sparking on the DC side you could lose the COBs to overvoltage, so you want to make sure you have a secure connection before applying power.
 
DoctorDelta9

DoctorDelta9

Well-Known Member
SupraSPL said:
Are you aiming to measure the current on the DC side? There is a separate setting for AC and DC. Also the red lead has to be plugged into the "10A fused" slot. If you are getting sparking on the DC side you could lose the COBs to overvoltage, so you want to make sure you have a secure connection before applying power.
Click to expand...
I think @bicit hit the nail on the head. The meter need to be in series instead of fighting the led for current in parallel. Makes sense. Dumb move on my part. Good thing I originally experimented on my crappy Chinese practice LEDs. I wasn't going to make the same mistake twice with my precious 50$ crees. I knew you guys would set me straight in no time
 
DoctorDelta9

DoctorDelta9

Well-Known Member
I won't even measure the Crees. Before I started on the grow setup. I ordered Chinese LEDs and drives on eBay for 10$ just to mess with them and figure it all out. I ended up retrofitting my nanocube fish tank using old laptop heatsinks and buck dimmers. Tank looks great and only cost me 40$ total. Less than the replacement compact CFLs. And the corals are booming
 
DoctorDelta9

DoctorDelta9

Well-Known Member
[/IMG]

I used the existing transformer and bridge rectifier to wire the laptop fan/sinks. Plenty of power. Wired to the existing switches and made holes for pots through the hood. Works perfect. Runs cooler. Brighter. I was pretty proud of myself. Plus I got myself some experience before tampering with $1200 worth of real lights and drivers. When I tried to measure current by touch in pos to pos neg to Nedgon the light terminals the light went out and meter went crazy. @bicit method makes more sense. The light were fine tho. I was more worried about my 150$ multimeter!
 
bizfactory

bizfactory

Well-Known Member
Ok so I've been thinking about this. 4x CXB3070s on a HLG-185h-C1400B (1.4A) mounted to the HeatsinkUSA 5.886 profile at 24" length and 2x 120mm fans at 5v. Without doing any fancy thermodynamic calculations, I think it should have plenty of dissipation, almost overkill. Am I wrong in that assumption?
 
bicit

bicit

Well-Known Member
bizfactory said:
Ok so I've been thinking about this. 4x CXB3070s on a HLG-185h-C1400B (1.4A) mounted to the HeatsinkUSA 5.886 profile at 24" length and 2x 120mm fans at 5v. Without doing any fancy thermodynamic calculations, I think it should have plenty of dissipation, almost overkill. Am I wrong in that assumption?
Click to expand...
Looks like it would be adequate, but not overkill. Things would get rather warm if a fan failed.
 
Zheol

Zheol

Well-Known Member
im planning a build and was looking at the Antec BigBoy fan to cool the sink that's if I don't go with 9 arctic11's but the bigboy is 12v .3amp and has a 3 speed switch on high it moves 136cmf I have one in my pc its a beast
 
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NastyN8t

Active Member
not trying to thread jack been lurkin for awhile just a lil paranoid to sign up but u guys have inspired me to build a liquid cooled cob set up.........how much are the heat sinks for 650w worth of cobs running u guys' I've got around $80 into an expandable water cooled set up. I'm currently running the radiator in the same room but I can remote plumb it anywhere......thoughts?
 
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DoctorDelta9

DoctorDelta9

Well-Known Member
NastyN8t said:
not trying to thread jack been lurkin for awhile just a lil paranoid to sign up but u guys have inspired me to build a liquid cooled cob set up.........how much are the heat sinks for 650w worth of cobs running u guys' I've got around $80 into an expandable water cooled set up. I'm currently running the radiator in the same room but I can remote plumb it anywhere......thoughts?
Click to expand...
From what I've read the liquid cooled setups aren't really worth the money. You can keep the cobs cool enough with a heat sink and fan. However there are several threads about liquid cooling, I haven't seen any badass, successful setups as of yet. Below 25C there really is no exponential gain in efficiency or lumens. And keeping the cobs at or below 25 isn't to difficult. You would be better off putting that $$ toward more cobs and run them softer. Better spread and better efficiency. But if you are just looking to experiment, I think a liquid cooled setup would be way cool, just not to practical.
Just my 2 cents. I'm still a new here. Hopefully some of the big dogs will comment on your post
 
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NastyN8t

Active Member
I can remove the heat from my room and my water block is cool to the touch ,I can make the blocks for about $3 per cob . Just an experiment with what I have on hand. I'll start a new thread..i might go airkewled if it's more reasonable tho.
 
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