DIY LED lighting?

BINKSY1973

Member
Joined
13 Nov 2008
Messages
201
Location
Oxford
Hello, first post here so please be gentle, lol

I like the idea of using led lighting, those drivers AC linked too earlier look a nice find, also would be using 3w leds with forward voltage of 3.7v (700ma)i have a 2 foot tank, 15 inches deep by 16 inches tall, was thinking 2 rows of 5? too much? So i emailed the supplier of those drivers and asked if it would be possiable to use one power source for two drivers, and i got a reply back saying that could be done, power wired in parallel. So if i was to use a 24v power source on those drivers what wattage would be needed for the above?

Cheers Gordon
 

SteveyG

Member
Joined
18 Oct 2008
Messages
77
Location
Yaxley, Peterborough
The limit on how many LEDs you can have is based on both the maximum current and maximum voltage from your AC adapter. SuperColey is using so many power supplies because they can only supply about 1A at 12V which is 12W. If your power supply can supply more current, you can have more drivers in parallel. If your power supply has a higher voltage (observing the maximum voltage of the drivers which is about 24V) then you can have more LEDs in series per driver.

The formulas would be as follows for one string of LEDs connected to a switching (not linear) constant current driver:

(Power supply voltage - Voltage drop of driver due to output transistors) / LED forward voltage = number of LEDs (round this figure DOWN)

Required power supply current = (((LED forward voltage * number of LEDs) + voltage drop of driver) / Supply Voltage) * LED current. (Note this excludes any inefficiency of the driver. I suggest you add 15%)

If you had a 24V supply, then you could have about 5 LEDs in series per driver, so two rows of 5 would be perfect.
Your power supply would need to supply around 1.4A. (preferably more so you are not running it near it's max)

Most switching constant current drivers should have the ability to vary the LED intensity, but 30W sounds a good start for a 2ft tank.
 

BINKSY1973

Member
Joined
13 Nov 2008
Messages
201
Location
Oxford
Thanks for the informative post with those formulas very helpful. I have just seen a 24v 2.65a 65w power supply on ebay, item no 250320031262. So looks good for my requirments. Those drivers Andy linked to earlier in the thread use a buck mode switching regulator so sound perfect.

So here is a recap just to confirm what im looking to do.

One 24v 2.65a power supply.

Two led drivers. (power wired in parallell)

10 3w leds forward voltage of 3.7v. 5 from each driver wired in series.

Thanks for all the info in this thread so far.

Cheers Gordon
 

SteveyG

Member
Joined
18 Oct 2008
Messages
77
Location
Yaxley, Peterborough
Yep, all sounds good Gordon.

James, you can use a PC power supply, but the ATX spec requires both the 5V and 12V lines to be loaded to properly regulate the outputs (and sometimes even to turn on). I think the 5V line requires somewhere near an amp load, and the 12V line about half an amp, which kind of throws any efficiency out the window as it is unlikely you'll drive your LEDs off the 5V line. It also doesn't help that PC power supplies are massively inefficient with low loads. It might be worth you finding something better suited unless this doesn't bother you.
 

BINKSY1973

Member
Joined
13 Nov 2008
Messages
201
Location
Oxford
Thanks Aptsys, i think this will be a project for next year, what with xmas looming etc. But good to know my plan will work.

Cheers Gordon
 

GreenNeedle

Member
Joined
19 Jul 2007
Messages
2,720
Location
Lincoln UK
Does this look right?

This plug runs 900ma at 12V. the current controller is where I think I may be wrong. I have points for positive supply (+), negative supply (-), control input (A). Then on the oposite side I have positive and negative cathode which I assume are where to connect the LED series to

From the positive cathode I then enter each LED on a positive and then exit the LED on a negative to join the next LED on a positive. At the end of the series I then return to the negative cathode on the controller.

seriesdiagram.jpg


AC
 

scottturnbull

Member
Joined
30 Oct 2008
Messages
132
SuperColey1 said:
Does this look right?

This plug runs 900ma at 12V. the current controller is where I think I may be wrong. I have points for positive supply (+), negative supply (-), control input (A).

It looks like you're connecting the negative supply rail to the control input.

Wouldn't you be better off with something like this?

It's more expensive than a separate driver and power supply for each bank of 4 x 3W. But it is combined, with less hassle, and designed to run either 9 x 1W LEDs @ 350ma, or 4 x 3W LEDs @ 700ma.

There's also a 16 LED driver capable of sourcing either 16 x 1W, or 8 x 3W LEDs, that includes dimming by adding some simple components, for about 30 quid each.
 

Voo

Member
Joined
24 Feb 2008
Messages
185
Location
Lincs
SuperColey1 said:
Does this look right?

This plug runs 900ma at 12V. the current controller is where I think I may be wrong. I have points for positive supply (+), negative supply (-), control input (A). Then on the oposite side I have positive and negative cathode which I assume are where to connect the LED series to

From the positive cathode I then enter each LED on a positive and then exit the LED on a negative to join the next LED on a positive. At the end of the series I then return to the negative cathode on the controller.

AC


I actually bought one of these controllers last week for my nightlights i was making using ordinary leds. You'll need to check the input and output as the +ve input is not on the same level as the output (ie if + input is at the top, + output is at the bottom on the other side).
 

BINKSY1973

Member
Joined
13 Nov 2008
Messages
201
Location
Oxford
Andy,

It also looks like to me that you have the positive on the outgoing side of the controller connected to the Negative. I just had a quick look at the picture on ebay at that controller and the + and - are clearly marked. But one way to be sure is to check with a multimeter (if you have one) Plug in the supply and power up the controller, leave the output side disconnected, put the red lead on the pos terminal, the black lead on the neg terminal, and it should read 12, if you have it the wrong way round it will read -12v. Make sure the meter is set to DC voltage. Hope that makes sense.

Cheers Gordon.
 

SteveyG

Member
Joined
18 Oct 2008
Messages
77
Location
Yaxley, Peterborough
Tomorrow afternoon I'm going to start work on my system. My HC 'cuba' seems to be suffering a little in my Rio 240 lit by two 54W T5's. I tested an additional 54W T5 on the aquarium tonight and immediately all the lower level plants started pearling, but it is impractical to add the 54W tube as the layout of the Jewel hood really causes problems with space and access. Suspended luminaries are out of the question too due to having two little feline terrors that love to sit on the hood and paw at the glass . The spare 54W 1149mm tubes are a real squeeze lengthways as well due to the plastic trim round the top and I'm not willing to pay for the special Jewel sized T5 tubes.

I'm going to be adding 32W (32 x 1W) of cool white LEDs with 45 degree optics and 5W of royal blue LEDs for moonlighting. I do have some stunning 180 lumen Luxeon rebel LEDs which I'd love to use, but they get a little too hot to run in the acrylic tube :(
 

GreenNeedle

Member
Joined
19 Jul 2007
Messages
2,720
Location
Lincoln UK
Looking forward to it. Can we see loads of close ups of the actual soldering etc as well as the complete series before you put them in the acrylic tubes?

AC
 

GreenNeedle

Member
Joined
19 Jul 2007
Messages
2,720
Location
Lincoln UK
Well I got bored and had a go at a series of 3.

Running from a 1000ma 12V adaptor. This is a pic of 9W of light in my living room with everything turned off (The camera is 12ft away from the LEDs and looking from the sides)
3afar.jpg


And here is a pic from 2ft away directly above. (My eyes are aching just from taking this pic!!!! Its like welding flash (if anyone knows what that is. Hope my retinas aren't burnt and wake me up in agony through the night ;))
3close.jpg


I will admit it didn't go as smoothly as I would've liked. This post was begging for advice until I edited just now. It wasn't working and then I decided to try each LED. 1 worked and the other 2 didn't. I think I may have burnt them trying to make the solder too neat and taking too long. Got 2 fresh ones and went splodge, splodge and then it worked.

One lesson learnt :)

AC
 

GreenNeedle

Member
Joined
19 Jul 2007
Messages
2,720
Location
Lincoln UK
As a final post of my test, I put the series of 3 on the front flap of my hood just to see what they look like. Wrong way round as it is 3 left to right whereas I will have 3 front to back and then 5 rows across. Crudely fastened them into my hood.

If anything I think the light looks better than the fluorescents!!! You can see the ripples on the substrate and shadows moving from the leaves etc. looks really cool.

So these LEDs at max are 3.7V. I am putting 3.5V in so I assume that means instead of pushing out 3W they are pushing out 2.8W?

Anyway here is the series attached to the front flap of the hood:
seriesonflap.jpg


This is a close up of the LED and heatsink screwed into the flap:
singleLED.jpg


This is how the tank looks with 48W (1.45WPG) of 4500K/6500K Fluorescent (This pic was at night with all the lights off etc):
fullfront-4.jpg


This is how the tank looks with 8.4W??? (0.25WPG) of 5500K LED all at the front (This pic is in daylight):
7Wtank.jpg


And a quick pic of the ripples/shadows:
front-4.jpg


Have to say I like it but thats where I stop for now. I have to get the rest of the LEDs and that will not be for a little while so tested, happy and confident it will work I can start planning a more suitable mounting method etc.

AC
 

SteveyG

Member
Joined
18 Oct 2008
Messages
77
Location
Yaxley, Peterborough
Looks good. My only comment is that the heatsinks look a little on the small side. What kind of temperature are they getting to?

Unfortunately I have little to show at the moment as I'm working on the PCB design first.
 

GreenNeedle

Member
Joined
19 Jul 2007
Messages
2,720
Location
Lincoln UK
No idea on temperature as I only had them on for a few minute each time testing and here for 5 minutes.

Hopefully they will be OK and the fans will help. Better than not having heatsinks at all like the method on the other forum.

AC
 
Similar threads
Thread starter Title Forum Replies Date
Mark Keetch DIY LED floodlights any good??? Lighting 45
john arnold Diy light Lighting 10
Carpman Branded or DIY Lighting 12
Ackroyd Juwel Helialux LED vs SPECTRUM Lighting 0
L Dennerle Nano Power-LED 5.0 - UK plug available? Lighting 2
Tom Raffield LED Settings Lighting 18

Similar threads

Top