DiY LEDs - How to Power Them

SupraSPL

SupraSPL

Well-Known Member
Abiqua said:
Pro and con's of using switching power supplies and drivers versus just powered drivers?
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It is possible to use 12V DC power supplies to power LED strings but but the conversion from 120V AC to 12V DC penalizes efficiency (50-80% efficient). There are high efficiency power supplies available (85-90%) but they can be expensive and add unnecessary cost and complexity. After the 12V power supply we have to use a DC to DC power supply to step the voltage back up above 12V. From my testing this step up is not very efficient (80%) unless the string is very short <12V.

Another option is to use constant voltage DC to power the strings but that only works if all the LEDs on the string have the exact same vF otherwise they will experience drastically differing currents.

So those are the reasons I recommend constant current drivers and that has been my experience but I am always open to learning new things so if anyone knows a more efficient way please advise us :weed:
 
midgetaus

midgetaus

Member
Mellodrama said:
Hey, Supra, I don't know if this is helpful or an annoyance. I made a quick sketch of a very basic "One COB, one driver" circuit. It's an attempt to help those who are trying to follow this stuff but don't have much electrical background. The sketch shows one of those Ideal COB holders but of course that's not necessary if the person just wants to solder directly to the COB.

View attachment 3003673

Now this may be a mistake, but I left out any mention of a fuse. I didn't know what type or ampacity to suggest so I left it out. If you want to tell us what you used, and you think it's important to include, I can draw another one.
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Thanks mello... if you had multiple drivers and multiple cogs how would you wire that? are all the drivers connected or is it one driver per power point

That is what i have searched for online but there doesnt seem to be any diagrams.
 
SupraSPL

SupraSPL

Well-Known Member
Gaius said:
Makes sense. I'm going to wire the ground cable to one of the metal sliders, then run small wires from that first slider to each of the other 3. Should help prevent accidental shock. Fuse should be easy to add to the line side.
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One of the best lines of defense against electrical shock is a GFCI outlet or extension cord ($7 on eBay). It is designed to sense any leakage in the circuit and shut it down quickly. I use them in my circuits and it helped me discover an arcing extension cord that my fan was plugged into. Any older extension cords that get loosened up and have rickety connections should be replaced. In my case I just cut the rickety end off and replaced it with a quality connector.

This is also the reason we recommend one driver per COB or to use relatively short LEDs strings. If we use a high voltage driver the DC side of the circuit gains more ability to overcome the resistance of our skin.
 
OneEyedCat

OneEyedCat

Active Member
Great thread,
I wish I was good enough with the soldering iron to try this. After looking at different kits and pricing parts I said to heck with it and went to Amazon.
Went with an Apollo 180 watt for less than $140 US, 6 band that actually only draws about 109 watts, so each 3W LED is only being driven at less than 2.5W each. we shall see how that works.
Keep up the sharing of good info.
 
Mellodrama

Mellodrama

Well-Known Member
Hi, midge -
My line drawing was flawed. I've deleted that post. I sketched it out from memory and made a horrible mistake. I drew the icons on the driver backwards. I used the AC icons on the DC side and the DC icons on the AC side. I don't know for sure what would happen if the driver is wired in backwards so that AC grid voltage is applied to the DC outputs but I'm guessing it wouldn't be pretty. So I apologize to everyone and hope I did no damage in the two days my sketch was out there for all to see. Please refer to Supra's diagram at the beginning of this thread.

AFAIK Gaius and Supra are duplicating that same basic circuit (plus fuses perhaps) over and over again for COB's. If you inspect the back side of Gaius' Battlestar you'll spot the drivers lashed onto the outer hull.

Lots of posts talk about stringing a gob of smaller emitters together in series and powering with one driver. That makes sense when you're talking about individual emitters that only draw 3 watts or so each. It wouldn't make any sense to power each LED with its own driver. You'd want to string together a dozen or so and use one driver that's properly sized for the combined load of all those individuals wired together in series.

Think of the COB's as a bunch of smaller emitters already wired together for us by the manufacturer and stuck together on one die.
 
WDIK

WDIK

Active Member
Driver for the Vero 18?

Mean Well APC-35-1050. Link contains PDF specs. It seems to hit the Vero 18 datasheet pretty much right on the numbers. It's a little more compact and cheaper than another Mean Well driver mentioned elsewhere for the Vero 18.

Thoughts?
 
MrFlux

MrFlux

Well-Known Member
WDIK said:
Mean Well APC-35-1050. Link contains PDF specs. It seems to hit the Vero 18 datasheet pretty much right on the numbers. It's a little more compact and cheaper than another Mean Well driver mentioned elsewhere for the Vero 18.
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That driver would pair well with a vero18, only drawback is the bit weak efficiency of 84%.
 
SupraSPL

SupraSPL

Well-Known Member
Yep thatd work. Vero18 should be about 29vF at 1050mA. Here is a cheap 1A driver but requires soldering and it says minimum of 32V volts. I have one on order and I will report back as soon as I get to test it.
 
WDIK

WDIK

Active Member
Anyone know the shipping times from Satisled? I had some of the Mean Well drivers in my shopping cart, but decided to wait and try the cheapos I already have coming.
 
PetFlora

PetFlora

Well-Known Member
Gaius

Gaius

Active Member
PetFlora said:
a ? if I may,

I ordered 2 cob/reflector lights said to be 75w. Turns out actual draw is only 48w +/- 2w , or ~ 45w actual, still @ $77 + free shipping...

Can I use a bigger driver to drive them harder, and if, yes, recommendations needed, or will I also need a higher wattage chip?

Thanks in advance

http://www.ebay.com/itm/Amazing-Growth-Reflector-Cup-75W-LED-Light-Grow-Panel-Integrated-COB-Hydro-Lamp-/190958710284?pt=US_Hydroponics&hash=item2c7606ae0c
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When you get them, maybe try them out first to see how they do. If they aren't adequate, pop the case open and try to find the model of the chip they used. Once you have that, it should be easy to determine what specs to look for.

I wouldn't push the enclosure much past the current wattage, as it may not have adequate cooling to be driven much harder.
 
Gaius

Gaius

Active Member
At 1A the Vero has a minimum vF of somewhere between 31V & 33V. Looks like it will power on and run. SupraSPL could probably tell you whether or not to drive them a bit higher. The recommended vF is somewhere between 36.8 & 38.6, so you might be able to go a little higher on the volts.



 
SupraSPL

SupraSPL

Well-Known Member
PetFlora it will be interesting to see what is in there. My suspicion is that the best upgrade for those modules would be to swap in a CXA3070 if it would fit and to reuse the driver.
 
bicit

bicit

Well-Known Member
SupraSPL said:
Yessir bicit that driver should work perfectly. Here are some numbers for the Vero29 3000K
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Out of curiosity, what does the "$x.xx/watt" value represent?

So I'm pretty sure I'm going to use those power supplies to run 7 vero 29's(4@2700k 3@4000k) on a 24" long 3.945 profile cooled by a pair of 80mm USB powered fans (2.5w) unless I need more cooling. I'm debating just mounting the power supplies to the heatsink to simplify wiring.

I've got an arduino sitting here as well. I'm going to see how I can over complicate things with this little doohicky
 
SupraSPL

SupraSPL

Well-Known Member
$/W is based on the cost of the COB divided by the actual dissipation wattage at a given current. So it gives you an idea where the value point is and allows you to compare the cost of each COB at each current level.

I should have one of those drivers in a few days it is on the way from Fasttech. If you want to wait to order them, I will test one as soon as I get it to find out their actual maximum vF and how much mA they actually put out once they are warmed up.I suspect it will be slightly lower than 1A but that seems perfect.

I will also test the driver efficiency. I am considering upgrading some of my COB drivers from 730mA to these 1000mA. Small hit in efficiency for the COBs but it might be made up by the gain in driver efficiency..
 
bicit

bicit

Well-Known Member
SupraSPL said:
$/W is based on the cost of the COB divided by the actual dissipation wattage at a given current. So it gives you an idea where the value point is and allows you to compare the cost of each COB at each current level.

I should have one of those drivers in a few days it is on the way from Fasttech. If you want to wait to order them, I will test one as soon as I get it to find out their actual maximum vF and how much mA they actually put out once they are warmed up.I suspect it will be slightly lower than 1A but that seems perfect.

I will also test the driver efficiency. I am considering upgrading some of my COB drivers from 730mA to these 1000mA. Small hit in efficiency for the COBs but it might be made up by the gain in driver efficiency..
Click to expand...
I'll cancel my order then. It would be nice to see some actual numbers before I purchase. It's either those or a meanwell LPC from jameco. Do you happen to know of any high efficiency and/or cheap USB power supplies?
 
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