# Cheap Lighting ideas?



## Brian Murphy

Ok, I've been looking around online at what my cheapest way of providing light to my new tank idea.  The tank is a clearseal one I've been using for keeping gerbils for a few years (needs re-siliconed), dimensions are 32"x16"x18" making it around 39 gallons or 150 litres.  I can't afford a brand new luminare at the prices they are asking.  I would like to just use normal T5 tubes like on james's planted tank idea James' Planted Tank - T5 Lighting On The Cheap but am struggling to find anything within my budget and what would be best to use. Any ideas please


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## Alastair

You could buy one of the Arcadia twin 39watt starter units which are about £30 then pick what ever tubes you want along with reflectors. They would probably be your cheapest option 


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## Brian Murphy

Alastair said:


> You could buy one of the Arcadia twin 39watt starter units which are about £30 then pick what ever tubes you want along with reflectors. They would probably be your cheapest option
> 
> 
> Sent from my iPhone using Tapatalk


 
I was actually just looking at that ..... would have to figure out a way of mounting it above the tank but that shouldn't be too hard.  Might go with that if no-one else comes up with any ideas


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## Manrock

Here are some 'cheap' options I've been looking at - might be what you want?

 T5 Aquarium 36" Fish Tank Overhead Lighting Two Tube System | eBay

 T5 Aquarium Fish Tank Overhead Lighting Two Tube System | eBay

Steve


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## jack-rythm

Manrock said:


> Here are some 'cheap' options I've been looking at - might be what you want?
> 
> T5 Aquarium 36" Fish Tank Overhead Lighting Two Tube System | eBay
> 
> T5 Aquarium Fish Tank Overhead Lighting Two Tube System | eBay
> 
> Steve


I think that second light is an all pond solutions light unit.. See is it's cheaper on their website?

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## Brian Murphy

Manrock said:


> Here are some 'cheap' options I've been looking at - might be what you want?
> 
> T5 Aquarium 36" Fish Tank Overhead Lighting Two Tube System | eBay
> 
> T5 Aquarium Fish Tank Overhead Lighting Two Tube System | eBay
> 
> Steve


 
I wish I had of seen that a few weeks ago before I bought this not realising I couldn't get proper Tropical tubes for it, but that alps looks the biz.  Now to sell this one I have


 T5 Aquarium Fish Tank Overhead light Lighting aluminum Lamp 3 Model UK Stock | eBay


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## Manrock

Manrock said:


> T5 Aquarium Fish Tank Overhead Lighting Two Tube System | eBay


 
Yes Jack - seems to be cheaper (with free delivery) from them. Any idea what these lights are like anyone?


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## jack-rythm

I do not have the new model that u found but the old model. They have done me wonders on a 3x1x1 ft tank. I had to take a bulb out but this was due to my own preference and growing style. Overall I imagine the newer model is just as good   

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## wazuck

Another option is DIY LEDs. You can pick up 10w LEDs from eBay with optics and a driver for very cheap. 




Mount them on heatsinks and suspend them above your tank and you could create a slick looking energy saving setup that will give you some nice shimmer. Adding in some warm and neutral whites will give a nicer colour rendition (something I'm working on now).


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## Manrock

Manrock said:


> T5 Aquarium Fish Tank Overhead Lighting Two Tube System | eBay


 
This unit is now cheaper on ebay, at £112 (cut from £124).

A question - The wife wants to have a 'moonlight' phase on my tank, after main lights go off. Would the Marine Blue tubes give a 'moonlight' effect in a tropical tank? Would there be any effect on the plants?


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## nayr88

wazuck said:


> Another option is DIY LEDs. You can pick up 10w LEDs from eBay with optics and a driver for very cheap.
> 
> 
> 
> Mount them on heatsinks and suspend them above your tank and you could create a slick looking energy saving setup that will give you some nice shimmer. Adding in some warm and neutral whites will give a nicer colour rendition (something I'm working on now).



Would love to see a more indepth walk trough of your LED DIY build mate. Would you start a new thread?


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## Brian Murphy

Got the Allponds 90cm black finish with 2 x 39w tubes, looks great and hopefully aid with my new forthcoming project


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## wazuck

nayr88 said:


> Would love to see a more indepth walk trough of your LED DIY build mate. Would you start a new thread?



I will make another one up soon and document it for you. I have a baby due in 10days so it may take a little while to find the time.


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## jack-rythm

wazuck said:


> I have a baby due in 10days so it may take a little while to find the time.


A little isaac (but female version)... god help us all...


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## rolexbene

I am looking at some led lighting solutions at the moment, going to get a load of 3w cree less mounted to led pcb bar and then mounted to an aluminium bar.  kinda like an aluminium version of this.




Other things I have been looking at are these two in combination...




 85~265V E27/E14/B22/G24 8-10W 5050 SMD 44 LED Light Lamp Bulb Cool / Warm White | eBay

and





 New Flexible E27 LED Lamp Holder On off Switch 60Cm Power Cable Cord w/ Clip #1 | eBay


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## jack-rythm

Quite a difference in style from the cool stylish aluminium LED light unit to the metal bendy coil light socket. That acrylic unit Looks pretty nice Mate, I think I would prefer the acrylic holder to the proposed aluminium?

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## wazuck

rolexbene said:


> I am looking at some led lighting solutions at the moment, going to get a load of 3w cree less mounted to led pcb bar and then mounted to an aluminium bar.  kinda like an aluminium version of this.
> 
> 
> 
> 
> Other things I have been looking at are these two in combination...
> 
> 
> 
> 
> 85~265V E27/E14/B22/G24 8-10W 5050 SMD 44 LED Light Lamp Bulb Cool / Warm White | eBay
> 
> and
> 
> 
> 
> 
> 
> New Flexible E27 LED Lamp Holder On off Switch 60Cm Power Cable Cord w/ Clip #1 | eBay



The ada unit uses lower powered LEDs. You may not be able to make it as slimline with 3w Crees due to needing them to be cooled a lot more so a heatsink with big fins would be needed. Possible using more LEDs than needed and running them at a lower MaH/Voltage would work with a slimmer heatsink. That Ada light is a work of art. I own some 3w Crees that I've yet to have a play with. Ill take a look and see what is possible one day.


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## rolexbene

> The ada unit uses lower powered LEDs. You may not be able to make it as slimline with 3w Crees due to needing them to be cooled a lot more so a heatsink with big fins would be needed. Possible using more LEDs than needed and running them at a lower MaH/Voltage would work with a slimmer heatsink. That Ada light is a work of art. I own some 3w Crees that I've yet to have a play with. Ill take a look and see what is possible one day.


 
Yeah that was my thinking, I have a dimmable driver that will run more led's than I need, so I was just going to stick a few extra on then reduce the current, I have a Cree XM-L 1000lm torch and the heatsink on that is tiny and the light is ridiculously bright, I could probably light my tank with 2 XM-L leds running at full power going by the brightness from the torch. I think it will work out with just the bar as heatsink... Going to try that to start with 9 3w budget led's because I can get 10 for £4, then if all go's well might think about some crees and getting some acrylic laser cut at uni. Have you seen these badboys for a wire free look.
 2P x 30CM Aluminium PCB Circuit Board for 6 x 1w,3w,5w LED in Series | eBay


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## Garuf

If you're on the market for t5's I've heard nothing but good things about these for the money.
Lightwave t5 2ft 2x24w [LIGHTWAVE T5 2FT 2X24W] - £59.00 : The Grow Home, first4hydroponics.com


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## wazuck

rolexbene said:


> Yeah that was my thinking, I have a dimmable driver that will run more led's than I need, so I was just going to stick a few extra on then reduce the current, I have a Cree XM-L 1000lm torch and the heatsink on that is tiny and the light is ridiculously bright, I could probably light my tank with 2 XM-L leds running at full power going by the brightness from the torch. I think it will work out with just the bar as heatsink... Going to try that to start with 9 3w budget led's because I can get 10 for £4, then if all go's well might think about some crees and getting some acrylic laser cut at uni. Have you seen these badboys for a wire free look.
> 2P x 30CM Aluminium PCB Circuit Board for 6 x 1w,3w,5w LED in Series | eBay



I'm unable to see the item but I did a similar search and I'm liking what I'm seeing. Just remember that mixing different colour leds will give you a better colour rendition so those boards are perfect. I may well buy one to play with and see what I can come up with. dialed down LEDs on them with a nice DIY controller etc built Into a well made enclosure would be really nice. Such a good find. I'm a bit obsessive when it comes to lighting. I've been looking into building an Ati style t5 dimmable luminaire. What driver are you using then?


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## ghostsword

I wonder how bright those leds really are..  they are cheap..


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## wazuck

Guess we should get hold of par meters after we get some builds done to see just how bright they are. The TMC mini 400 is what 12watts? And they aren't Crees. So four Cree XM-L 3w LEDs should better one of them. I believe the 10w LEDs output about 1000lm at 700mah. So I'd say they are capable of growing plants. Would be nice to have some par readings tho.


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## dw1305

Hi all,


Garuf said:


> If you're on the market for t5's I've heard nothing but good things about these for the money. Lightwave t5 2ft 2x24w [LIGHTWAVE T5 2FT 2X24W]


I've got 11 of the 8 x 54W 4' units of these in the glasshouse and they seem pretty reliable.


rolexbene said:


> Have you seen these badboys for a wire free look.


I didn't know about these either, and they look very useful, is there a UK based retailer?

cheers Darrel


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## rolexbene

wazuck said:


> I'm unable to see the item but I did a similar search and I'm liking what I'm seeing. Just remember that mixing different colour leds will give you a better colour rendition so those boards are perfect. I may well buy one to play with and see what I can come up with. dialed down LEDs on them with a nice DIY controller etc built Into a well made enclosure would be really nice. Such a good find. I'm a bit obsessive when it comes to lighting. I've been looking into building an Ati style t5 dimmable luminaire. What driver are you using then?


 
Well bout the driver a while ago for about £6 I think, its basically a dimmable version of this comes with a potentiometer to dim it that I can build in to the stand:
 36W LED Driver Power Supply for 7-12 x 3W LED 100-240V | eBay
Also going to give these a go for testing, not as bright as crees but will give off less heat and for the price can't complain.
 10pcs 3W High Brightness LED Beads LED Lamp 180~200Lm Cool White 3.6~3.8V | eBay
Also these pcb's are only 11mm wide so would fit in to recessed aluminium profile bar with 3w led's.
This place offers  recessed aluminium profile bar with free shipping for a good price and would fit the pcb
1m Flat Recessed Aluminium Profile/Extrusion + Clear/Frosted Diffuser, Profiles, Extrusions, LED Profiles, LED Extrusions

Other cool unrelated lighting to look at are these sick cree mini torches, got one on my bike and its brighter than the cars
 New 1000lumen TrustFire Mini CREE XML T6 LED Flashlight Torch Keychain+Battery | eBay

And these bulbs are sick too:
 VINTAGE ANTIQUE LARGE FILAMENT E27 EDISON SCREW GLOBE LIGHT BULB 125mm 40W BNIB | eBay

Also the one of the best led shops on ebay is this one:
1 3 5 10 20 30W HIGH POWER LED, Luminus SSC CREE items in LED-DNA store on eBay!


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## wazuck

Just came across these




They are Cree XP-G 6000k search lights. That one is 36x3w so 108w @6000k. 25 degree beam angle. 7200lm. The warning says looking directly into the light can cause instant blindness. I'm sure with a little bit of tinkering that would be a nice light. It's IP 65 rated. So just really needs to be dimmable as that is far too much light. Even if it was mounted on your ceiling  anyway the auction ends in an hour and it's on £17 so it is on the cheap end for lighting solutions


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## wazuck

Bene. I like your pcb board idea a lot. I think I'm going to have a go. I like this board 



20 LEDs I would probably have to run 1w or even 0.5w LEDs to keep the light down. Just searching for the right mixture of LEDs now. Does anyone know if say I had 100lm LEDs. Would having 2 make it 200lm or would you lose some? Cheers.


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## wazuck

So my thoughts on the LEDs are to use an equal mix of warm white and blue LEDs as they should balance out nicely and possibly adding in some greens. Then the rest as cool white or even 10k+ to give it a temperature closer to what takashi has for his halides. That should give a nice colour rendition. I'd estimate that each pcb setup would cost around £20 at most. The options would be either 0.5 or 1w LEDs so each unit could run as a 10w or 20w. 20w would probably be too much light and would be throwing out around 60w of T5 equivalent light as an estimation. I'm not sure what the shimmer would be like as I normally use 3w+ LEDs. The colour mixing shouldn't be a problem as no optics would be added. Anyone got any input?


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## rolexbene

wazuck said:


> Guess we should get hold of par meters after we get some builds done to see just how bright they are. The TMC mini 400 is what 12watts? And they aren't Crees. So four Cree XM-L 3w LEDs should better one of them. I believe the 10w LEDs output about 1000lm at 700mah. So I'd say they are capable of growing plants. Would be nice to have some par readings tho.


Just to correct you they output around 1000lm at 3a this is the problem I am having is finding a suitable driver that will output around 2.5a (2500mh). the only decent solution I can find are drivers for use with batteries, but I am not massively electronically competent so could do with some advice I anyone knows of a solution.


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## rolexbene

What heat sink and mounting you think wazuck? my biggest problem is having an open top look but finding a mounting solution. ceiling mounting would be the easiest but my ceilings are too high to run wires and look good IMO.


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## wazuck

Well aslong as the LEDs are well under driven the heat sink shouldn't be a problem. You should be able to get away with a very slim fixture. The more powerful the led tho and the greater the cooling needs. I would like to say those led beads at 1w/0.5w would run pretty cool off just the pcb boards but until I buy my LEDs and my board turns up I won't be able to let you know.


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## Mikster

Hi, i have been reading this thread. i have ordered and received the below items, i plan testing these over the next few weeks.

Have you had much joy or encountered problems? these seem to get very hot  

Driver
 12V 5A 60W Switch Switching Power Supply Driver For LED Light Strip 200-240V NEW | eBay
Lights
 10W High Power LED Chip Warm White For Floodlight Spotlight Light Lamp Bulb DIY | eBay
And
 10W 455nm High Power Blue LED Light Lamp Bulb 150lm 12V | eBay


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## wazuck

Just out of interest. Why have you included a 10w blue led bulb? I would consider adding in some different temperatures of white led. Also these leds need mounting to a heatsink for the cooling. Be it a big heatsink or a small heatsink with a fan is your choice.


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## Mikster

I added blue, firstly its my understanding the blue part of the spectrum is used for a large part of photosynthesis and secondly as this is an experiment and i kind of like a bluish hint so why not  I have tried with red LED strips, but it makes things look pink. we will see how it looks, might look with rubbish with the blue.

I have a newish CPU heatsink i have be using for testing, but i am considering a few Arctic Cooling Alpine 11 GT Rev.2 Quiet CPU Cooler  - Aria Technology


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## rolexbene

Yeah I guess the blue would give you a marine look. 5a driver so I guess you would need to run 6 of these 10w led's in parallel. It's funny as all the drivers I have been looking at keep the amps at a constant and change the voltage to run the led's in a series circuit, still either should work ok. you will need some monster heatsink for this one though, you can get them in a single aluminium heat sink quite cheep from china if you don't mind waiting a couple of weeks for delivery, then make a single hanging unit similar to ones sold for big £, however this all depends on how you want to mount these badboys. If your going to be using fans, it might be worth looking in to how many amp these take up and integrating them in to the 12v circuit, to save on  running more cables. Goodluck and let us know how you get on.


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## rolexbene

wazuck said:


> Well aslong as the LEDs are well under driven the heat sink shouldn't be a problem. You should be able to get away with a very slim fixture. The more powerful the led tho and the greater the cooling needs. I would like to say those led beads at 1w/0.5w would run pretty cool off just the pcb boards but until I buy my LEDs and my board turns up I won't be able to let you know.


 
I have ordered some PCB's and some cool white 3w led's, and am going to order some 4mm aluminium strips as heatsinks, if all go's well with this I will sandwich the bar in between some bent acrylic to form a aquasky look, maybe a bit of braided lighting cable to finish it off. Just wanted to say if you have an excess of leds that are not cool white spectrum, I can do you a swap if you want, need to mix it up a bit but don't want to buy loads more.


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## Mikster

Rolexbene,

Its my understanding (i am new to this LED/electronic lark) you run LED's in series up to the voltage i.e. 4 x 3volt LEDs in series = 12v for a 12 volt driver/power.
In this case the driver is 12v and so is the LED, so its parallel and the LED gets the full voltage. As they draw 900ma you could have up to (5000/900)  5.5 x 12 volt LED's or i have made a mistake


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## ian_m

LED's are driven by current NOT voltage (unlike a normal light bulb), thus all this talk of what voltage LED's require is wrong. In terms of water (as we are all involved in aquariums) voltage = water pressure and current = flow rate. LED's require current ie so many litres/second in water terms, not pressure ie bar or PSI.

So a to connect more than one 900mA LED, you wire them in series so each one has 900mA passing through it. If you wire them in parallel, from say a 900mA LED driver, you will probably end up with one bright'ish LED (hogging most of the current) and all the rest dim (taking the remainder of the 900mA current).

Mikster, that PSU is not suitable for driving LED directly as it is constant voltage (12V), if you connect it directly to LED's the LED's will draw the wrong, most likely huge, current and either burn out instantly or get very hot and burn out very quickly. In fact the Ebay advert says the 12V supply is "For the Led Lights Strip Power Supply". Thus you connect the 12V supply to LED light strip power supply, which I assume supplies a constant current, and then to the LEDs.


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## Mikster

So this thing is a power supply for another driver (or something similar) that would explain the incredible heat generated by the LED when i tested it.

This is entirely hypothetical, if this power supply (not driver?) feeds a 12v LED, the LED will draw as much current (flow) as possible until it burns out, heat or otherwise, so what it needs a is a resistor in between to limit the current or flow? Although i wouldn't have a clue how to calculate this. BTW i am not proposing using this thing anymore.

Making a massive assumption here again, but the LED strips you can get look like they have resistor every couple of LEDs, is that to limit the flow?


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## rolexbene

ian_m said:


> LED's are driven by current NOT voltage (unlike a normal light bulb), thus all this talk of what voltage LED's require is wrong. In terms of water (as we are all involved in aquariums) voltage = water pressure and current = flow rate. LED's require current ie so many litres/second in water terms, not pressure ie bar or PSI.
> 
> So a to connect more than one 900mA LED, you wire them in series so each one has 900mA passing through it. If you wire them in parallel, from say a 900mA LED driver, you will probably end up with one bright'ish LED (hogging most of the current) and all the rest dim (taking the remainder of the 900mA current).
> 
> Mikster, that PSU is not suitable for driving LED directly as it is constant voltage (12V), if you connect it directly to LED's the LED's will draw the wrong, most likely huge, current and either burn out instantly or get very hot and burn out very quickly. In fact the Ebay advert says the 12V supply is "For the Led Lights Strip Power Supply". Thus you connect the 12V supply to LED light strip power supply, which I assume supplies a constant current, and then to the LEDs.


 
What are you talking about if you wire 4 3v led's in  series they will draw 12v, this is why they sell drivers that are rated from "30-70v  12-20 x 3w" Not sure if this is the same Mikster driver, but this is exactly how most of the 3w led drivers work. If you don't believe me just look at the top of this standard led driver:
 60W LED Driver Power Supply for 12-20 x 3W LED 100-240V | eBay


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## ian_m

LED's do not have a rated voltage, you don't get 3V LEDs (OK might get 5V & 12V but they have a resistor in), you get so many mA LED's, so your statement "4 3v led's in series they will draw 12v" make no sense. In water terms, "4 3psi things in series will draw 12psi" 

What happens is when you pass the rated current through the LED is drops a voltage, thus @900mA will drop 3V for instance. Note however this voltage depends on temperature at the rate of -2mV/°C so will be less as temperature rises. So connect 4 LED's to 12V, will most likely draw more that 900mA and as they warm up will draw more current until they are destroyed.

The driver rated at "30-70v 12-20 x 3w" means that it will drive 12-20 3W LED's in series ie varying the output in the range 30V to 70V so as to always put 680mA through the string of LEDs.

I fear you also might be confusing V - Voltage with W - watts (power).


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## rolexbene

what? I have not confusing V with W... here is the spec sheet from the leds I just bought clearly stating the V and W:
*Specifications:*1)Output power:* 3W*2)Forward Voltage:* 3.6~3.8V*


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## Mikster

Certainly is confusing

This chap looks like its setup in series   DIY High Power LED Aquarium Lighting – Part V at Ken's Aquariums & Pond


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## rolexbene

Mikster said:


> Certainly is confusing
> 
> This chap looks like its setup in series  DIY High Power LED Aquarium Lighting – Part V at Ken's Aquariums & Pond


 
What you need for your driver mate is something like this:
 LED Driver Power Transformer 30w-54w (10-18)x3w waterproof AC85~265V 680mA | eBay

It would run 3-5 10w leds, and would run them at 680ma that is about 70% brightness

Or here is one that would run them at 100% brightness

 AC 85-265V DC 20-38V 900mA 30W Waterproof Transformer LED Power Supply Driver | eBay


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## Mikster

Thanks for that, they both look top dollar!

Going to give LED Driver Power Transformer 30w-54w (10-18)x3w waterproof AC85~265V 680mA | eBay a go, best to under power

but I am still confused, why this is unsuitable  12V 5A 60W Switch Switching Power Supply Driver For LED Light Strip 200-240V NEW | eBay for running a one/two/etc 12v LED's in parallel? volts are the force behind the current so why will this burn out?

think i might get an electronics book off amazon, doubt they do one on LEDS


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## rolexbene

Mikster said:


> Thanks for that, they both look top dollar!
> 
> Going to give LED Driver Power Transformer 30w-54w (10-18)x3w waterproof AC85~265V 680mA | eBay a go, best to under power
> 
> but I am still confused, why this is unsuitable  12V 5A 60W Switch Switching Power Supply Driver For LED Light Strip 200-240V NEW | eBay for running a one/two/etc 12v LED's in parallel? volts are the force behind the current so why will this burn out?
> 
> think i might get an electronics book off amazon, doubt they do one on LEDS


 
Yeah me too, from my understanding your current driver should work fine, I have a feeling that ian_m just jumped in to the conversation without properly reviewing the information, I can't see why you would have a problem with 6x 12v 900ma leds in parallel with a 12v 5a driver, giving you a 820ma drive current for each led, the only issue that I can see is that you won't be able to dim them. Someone please feel free to correct me if i'm wrong


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## rolexbene

Mikster said:


> think i might get an electronics book off amazon, doubt they do one on LEDS


 
Well they defiantly do have led books on amazon, here are a few ebooks on led's. 

http://dl.dropbox.com/u/4744698/0470612797Lighting.pdf
http://dl.dropbox.com/u/4744698/LED.Lighting.pdf
Power Supplies for LED Driving - Steve Winder - Google Books


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## ian_m

The power supply above is a constant voltage power supply (12 Volts) in this case designed for connection to an LED driver not directly to LED's.

Below is a circuit I used in my circuit simulator with 3 high power LEDs (900mA in this case) being driven directly from a power source ramping from 0V to 12V.




Below is the results.



X axis is applied voltage and Y axis is current through diode chain.
As you can see the current, as not being limited, very quickly rises to quite a large value (nearly 5A in this case), which would destroy the LED's. This is why you employ constant current (or a current limiting resistor) or else the LED's will be destroyed.

Adding an 8.2Ohm current limiting resistor in series with the LED's produces this, current 800mA at 12V, so OK for 900mA LED's.



The problem with this is the power dissipation of the resistor is 5Watts which means big'ish resistor, issues with getting rid of the heat and only about 40% of power is going into the LED's.


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## rolexbene

ian_m said:


> The power supply above is a constant voltage power supply (12 Volts) in this case designed for connection to an LED driver not directly to LED's.
> 
> Below is a circuit I used in my circuit simulator with 3 high power LEDs (900mA in this case) being driven directly from a power source ramping from 0V .


 
But he is talking about running the led's in parallel, not series like in your diagram??


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## jack-rythm

Can Anyone on this forum say they are qualified to correct this discussion? I think there are a few people including me that would like to know the correct information. Obviously 2 very strong arguments here that can be confusing for an LED beginner such as my self!   

Sent from my GT-I9100 using Tapatalk 2


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## ian_m

rolexbene said:


> But he is talking about running the led's in parallel, not series like in your diagram??


You never run LED's is parallel, as previously explained, as slight variations in LED manufacturing parameters means that one of the LED's (the one with the lowest threshold voltage) will hog all the current and potentially burn out.

Below is the current through 2 LED's in parallel but with one having 5% difference in its threshold voltage, as can been seen one takes more current than the other.


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## rolexbene

You may find this article useful from Reeflights.com a specialist in led lighting describing how to run very similar led's using a 3.2A driver in parallel.
Wiring Diagrams | Reef LED LightsReef LED Lights


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## ian_m

rolexbene said:


> You may find this article useful from Reeflights.com a specialist in led lighting describing how to run very similar led's using a 3.2A driver in parallel.
> Wiring Diagrams | Reef LED LightsReef LED Lights


Observe the balancing 1Ohm resistor not shown on the diagrams.

And repeating my simulation of parallel LED's but with limiting resistor in each string, no current hogging occurs and both LED's take roughly the same current.


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## Mikster

I completely understand running lower voltage LED's in series from a higher Voltage low amp driver works, its documented on loads of sites blogs etc.
But, how comes running 1 12v LED from a 12v Power supply doesn't work?
if i was to have a 12v 900ma power supply it would work?
its the fact this power supply runs 5a (even though its 0-5a) will blow the one LED?
if i split the amps over 5 or 6 12v LED's then is safe?

Its just me but Rolexbene's link above makes complete sense to me, this doesn't. Not that i mind binning the power supply its only a few quid. My inner geek is now curious.


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## ian_m

Mikster said:


> But, how comes running 1 12v LED from a 12v Power supply doesn't work?


Its because there is no such thing as a 12V LED. LED's run on current eg 900mA etc.

When you push a current through an LED it generates a voltage across the LED, this voltage, for white LED's for instance, is in the range 3 to 4 volts, depending on LED, temperature, current, manufacturer, manufacturers batch, age etc. So there is really no fixed voltage rating for an LED.

The LED voltage is quoted so you don't attempt to drive say 20 LED's from an LED driver that can only generate 40V maximum output. To drive 20 white LED's with each being about 3.5V you would need a power supply that generates at least 70V output to stand any chance of getting current through them.


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## rolexbene

Mikster said:


> I completely understand running lower voltage LED's in series from a higher Voltage low....


 

_If i was to have a 12v 900ma power supply it would work?_
Yes any DC power supply running at 12v 900ma or less will work

_its the fact this power supply runs 5a (even though its 0-5a) will blow the one LED?_
Yes I believe it will blow 1 led but am not 100%, maybe try asking the sales person.

_if i split the amps over 5 or 6 12v LED's then is safe?_
_I beleive it is safe, Ian_m does not for some reason. Guess your just have to risk blowing an led and try it. If it __doesn't work just sell the driver on and buy a variable voltage fixed amp driver like the ones I suggested above. I am no expert, just share a similar interest to you and am filling you in from my __research and__ basic understanding of electronics._


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## Mikster

Ok so what V and amp power supply would you need to run one of these?
 5x 10W Watt High Power Bright LED Pure Warm/Cool White Light Lamp DIY Bulb 9-12V | eBay


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## rolexbene

This wHigh Power Bright LED Pure Warm/Cool White Light Lamp DIY Bulb 9-12V | eBay[/quote]
This would dod the trick!
 High Power 10W LED Driver AC 85-265V to DC 9-12V 900mA | eBay


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## Mikster

rolexbene said:


> _If i was to have a 12v 900ma power supply it would work?_
> Yes any DC power supply running at 12v 900ma or less will work
> 
> _its the fact this power supply runs 5a (even though its 0-5a) will blow the one LED?_
> Yes I believe it will blow 1 led but am not 100%, maybe try asking the sales person.
> 
> _if i split the amps over 5 or 6 12v LED's then is safe?_
> _I beleive it is safe, Ian_m does not for some reason. Guess your just have to risk blowing an led and try it. If it __doesn't work just sell the driver on and buy a variable voltage fixed amp driver like the ones I suggested above. I am no expert, just share a similar interest to you and am filling you in from my __research and__ basic understanding of electronics._


 
Its ok, i dont mind blowing stuff up, least we will know for sure.


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## Mikster

rolexbene said:


> This wHigh Power Bright LED Pure Warm/Cool White Light Lamp DIY Bulb 9-12V | eBay


This would dod the trick!
 High Power 10W LED Driver AC 85-265V to DC 9-12V 900mA | eBay[/quote]

I looked at them originally, but i thought i could get a 5a one and save on running cables, that will teach me to be lazy.


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## ian_m

Mikster said:


> This would dod the trick!
> High Power 10W LED Driver AC 85-265V to DC 9-12V 900mA | eBay
> I looked at them originally, but i thought i could get a 5a one and save on running cables, that will teach me to be lazy.


Yes that would work, both LED and driver are rated 900mA. The driver can produce 9-12V so enough voltage to drive 900mA through the 9-12V running voltage of the quoted LED.


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## rolexbene

Mikster said:


> This would dod the trick!
> High Power 10W LED Driver AC 85-265V to DC 9-12V 900mA | eBay


 
I looked at them originally, but i thought i could get a 5a one and save on running cables, that will teach me to be lazy.[/quote]

No the trick is to get one driver that supplies 60v at 900ma and wire the led's in series.


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## ian_m

Actually these LED's with multiple chips per package are a bit of a nightmare as well especially if not from Cree, Osram etc.

The ones you pointed out consist of three parallel strings of 3 white LED's and suffer from current hogging when LED's are in parallel. Below is picture showing what can happen. One column is hogging the current (and being over driven) at the expense of other two columns. Overall light output is same'ish but lifetime is seriously reduced due to overdriving one column.





The big boys, Cree, Osram get round this if they have more than one LED in a package, because they make the LED's, they use LED's from same wafer thus have same electrical characteristics and employ clever LED material so to current limit. Generally though for multiple LED packages they place all the LED's in a series, thus need say 70V drive or pin out each LED string individually.


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