A year back I bought all of my led lights. With how much diy costs have dropped I kinda regret it but at the time it was a great deal. Now though i’d like to build a setup with lm561c. Yet I don’t want my investment to be a total loss. So I figured I can disassemble my current leds and use the drivers to run the lm561c. Also i’d like to use the old diodes extremely under driven in my veg tent to boost efficiency and also get use out of them. Between the 4 lights i’ve got 16 120w drivers. I’d like to keep 2 for veg and the rest for the lm561c. Does anyone know how under driven your average 5w diode can be ran? So I can figure out how many led’s i can wire up. Thanks in advance.
As long as you have enough forward voltage you should be able to provide as few amps as you want and they will put out some light. How much light do you want to get from them? Also what LEDs are your old ones? The “c” diode is only 10% more efficient than the “b” iirc.
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I’ve got 2 900 meizhi and 2 znet 600. I took them apart when I 1st got them so I could check the drivers. To make sure the lights were relatively as advertised. So i’m sure in theory it’ll work. I’m not worried about intensity so much. Canopy penetration in veg won’t be an issue I feel. It’ll be for a 2x4 tent so i figured 30 watts per sq foot should be enough. Also thanks for the heads up lm561c chips can be confusing but think i’ve got the difference between c, b, b+ nailed down.
I’m not familiar with either of those got a pic of the drivers? Do you know if they are constant current or constant voltage? If you are just looking for efficiency you might replace the diodes and use the drivers depending on what you have.
I mean yes efficiency is an issue and a large part of why I want to build a unit. But if i’ve got something bought and paid for i’m going to put everything to use as best i can. I’m incapable of letting things go to waist lol. I’ve got everything packed in the attic atm bc i’ve been forced to take a break (i should have wrote down the volts previously). So pics aren’t avil but good looking out bro.
Found these doing lots of digging last night. Seems like their almost giving them away. At 85$ with shipping for 1800w at 48v you could power a whole lota leds. It’s also decent on efficiency too 92%. Not really seeing a down side besides if you don’t need that much power. Anyone know if you could wire in something to adjust it?
Haha well I assume @Albannach might be able to help
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Not a straightforward job cos of the voltage but yeh you could string together loads of cobs in a mix of connections - series and parallel to match the voltage. You would need a load of high power rated resistors, maybe wire wound ceramic types for current limiting duties.
I personally cant be arsed with all that hassle and fully adjustable 24 & 36V drivers can be had from China for cheap. Just need to choose your leds, cobs or strips 
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See ^^^ hes the man. . . and I have trouble plugging in the toaster hahaha @Albannach
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lol i cant afford to pay other people to build stuff for me so i do it myself.
Here is the kind of cheap driver i’d pick if i couldn’t get the sealed meanwell drivers.
https://www.ebay.co.uk/itm/DC-5V-12V-24V-36V-48V-Switch-Power-Supply-Driver-For-5050-LED-Strip-AC-110-220V/371933063056?hash=item5698f02790%3Am%3AmIWGf6ci5yazxZqdto-uIiw&var=640877037132
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Yup step ahead ya
48v, 800 lm561c, 280x900mm 80$
With the size won’t need any heatsink, just u channel for support. Plan on 8 boards will give me around 7,500 lumen per sq ft n give crazy coverage in my 6.5 x 6.5 ft tent. All for around 1000$ hard to beat.
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Yeh that would work voltage wise but you would also need a current limiter or those leds will probably run off on you and burn out. They need a fixed current cos at the end of the day they are a diode. Check out a site called LED Gardner bro
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Whats the difference between constant current and fixed bc to my knowledge its constant at 1800w.
Same thing bro, is that driver you linked to constant current and if so what it’s rating. I couldn’t find any specs on that ebay listing and i cant read the label in that pic lol
Here ya go http://dcpower.eaton.com/3g/APR48.asp
They’re designed for super expensive tela equipment. I did a quick look at specs but now u got me 2nd guessing. Yet for what they’re intended for should be legit
I cant see what the current output is anywhere. Have you already bought this driver bro?
Nope not yet but it says right on the page constant power output. Can’t see a company purposely frying expensive tela comunication equ.
You need to know what that current is though. The seller recommends an HLG-320H-4B which limits the output to 6.7A @ 48V. I wouldn’t exceed those ratings on that board if i were you.
BTW have you got a full quote including postage from that alibaba lot? I have found they usually double the list price when they add the postage.
Huh? I’m confused if it says constant current of 1800 watts at 48v then we can figure out that’s 37.5 amps. That puts it at 4.68 amps per board. No i haven’t got the shipping yet. Other guys have with good results. Even if its crazy can go with r2t mufue etc to shop around. Also with shipping never use fedex or dhl. I’ve been hit by both for holding fees that are half of the price of what i bought.
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The reason current is brought up is because that is how you’d optimally drive an LED.
You can do the same thing with a voltage mode supply but you have to get things to match-up with the configuration of the LEDs such that both the voltage and the current are within the desired range.
With a current mode supply, you essentially command the amount of current you want to feed through the LEDs and the voltage will vary (up to a maximum) to make it “happen”. The voltage drop of the LEDs will vary depending on the current being driven and the supply will respond.
With a voltage mode supply, you vary the voltage which will produce a current based on the configuration of the LEDs. This is more tricky to get right. The voltage drop of the LEDs will vary as the current through them changes. And, the voltage drop will probably vary over the lifetime and temperature of the LEDs as well.
For instance, if you put a 48V voltage source across a 3V LED, disaster. Current is unbounded. If you put a 1A limited current source across an LED, the supply will vary the voltage up until 1A is achieved. Assuming the LED is rated for 1A, the voltage should be within the proper range for the LED and all is well.
As another example, let’s assume you have a 6 volt voltage mode supply. Across the supply you have two LEDs in series that just happen to have a 3V drop with 1A of current. Everything is kosher. 3Vx2 = 6V drop = 1A current. But what happens if one of the LED shorts out? The supply will try to maintain that 6V across them. In order to do so, it will increase the current output (up to a maximum). Assuming the LED has a linear current/voltage relationship, the current will increase to 2A to get 6V. If the single working LED is not rated for that current, it will consume itself.
On the other-hand, let’s assume you have a 1A current mode supply. Across the supply you have two LEDs in series that just happen to have a 3V drop with 1A of current. Everything is kosher. 1A = 6V drop. Supply is now at 6V. But what happens if one of the LED shorts out? The supply will try to maintain that 1A across the LEDs. In order to do so, it will decrease voltage until 1A is produced. The voltage is reduced to 3V. A safer, but not foolproof, scenario.
You can do either, voltage mode or current mode, but the current mode is the preference for both ease and safety.
Constant power output probably means 1800W. So, if your voltage drop is 32V, then the supply is capable of driving 56 amps while it attempts to produce the 48V across the 32V drop. And, it will do so if allowed. E.g. the potential need for power resistors inline to limit current depending on the configuration.
It’s a very nice supply on the cheap. I might buy one for other uses. Nothing wrong with what you are thinking. But it will take some care to utilize it for LEDs, I’d think.
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