# My DIY LED retrofit



## flygja (18 Aug 2010)

Here's are some pics from my DIY LED lighting. I used 12 pieces of Cree XR-E 3W LEDs driven by 2 Luxdrive 1000mA buckpucks. The whole thing is powered by a 24V 4A laptop power supply. 

It all started with a bog standard Dolphin 60cm 2x18W lighting unit. Ripped out all the innards and cut a whole on the top for a fan. A fan is needed because LEDs do get very hot and their reliability is directly related to its operating temperature.





These are the buckpucks I used. They are constant current drivers meant for LEDs. Won't go into the science but LEDs need a constant current to maintain a constant output. These are also dimmable, which adjusts the current.




Power comes into the unit via the side cap. I removed the original AC cable and replaced it with a DC socket. You can also see the potentiometer I added for dimming. It worked for the first few days but it no longer dims. No idea why, too lazy to rip it out to find out. At least its brightest in default mode.




Bought a standard 2x20W aluminium reflector and cut it down to size so it fits into the casing. Note complex calculations happening   




A test run once all the LEDs are connected. LEDs are supposed to be connected in series - 6 LEDs to one buckpuck.




LEDs are then glued with thermal paste + 2 drops of super glue on the side of each LED. 




The fan is a normal 12V 80mm PC case fan. Had to attach a 5W 180 ohm resistor inline because my power supply was 24V. 




Fan is then attached to the casing.




Everything is then slotted into the casing. I added some silicon glue on each side to hold the reflector in place.




Test firing!




What it looks like from the bottom. Don't forget to put the acrylic splash protector back!




It's been running for almost 2 months now with no issues (except the dead dimmer). Growth has been pretty good, with Rotala nanhensjan growing about 2 inches per week and Rotala wallichi growing an inch a week and maintaining its red colour. Still waiting for Jap hairgrass to take off. Limnophilla sp Vietnam is starting to creep!





Questions and comments are most welcomed.


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## GreenNeedle (18 Aug 2010)

Check out the LED schematic thread.  I posted some info on LED advantages in there.  May be a downer for you to read but will 'enlighten' ('oops scuse the pun).

viewtopic.php?f=20&t=11269

r.e. the fan.  Can you hear it?  If so I would use one of these.  Fluid dynamic bearing, looks cool and barely audible plus cheap too:
http://www.play.com/PC/PCs/4-/15476567/ ... oduct.html

p.s. the retro looks cool.  Nice job on it   I would just forget the luminaire shell and build something the footprint of your tank to use the spacing advantage that you lose by 'squeezing them in the shell.

AC


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## flygja (18 Aug 2010)

Thanks SuperColey!

My LED retrofit was more of a copy-someone-elses rather than science. I'd like to DIY my own drivers one day once I have time and determination. I can't hear the fan unless I get to about... 5 inches away from the fan. I chose a 180 ohm resistor which dropped the voltage of the fan to < 12V. I live in Malaysia by the way, where there are lots of ambient noise from ceiling fans. I lived in Australia for a while and I know that winter nights are deathly quiet, so the UK maybe be the same. A low RPM fan with good bearings like the one you posted would be superbly quiet. My ears can't detect anything below 24 dBA.

I couldn't build the luminaire footprint either because I have no woodworking tools, or skill for that matter  Something to consider though if the tank is much bigger.


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## GreenNeedle (18 Aug 2010)

lol.  I had no woodworking tools or skill until I started. he, he.  Can you bend metal?  That luminaire looks like it could stretch the footprint although then you would have to cut new glass and ends. lol.

I tried the standard fans and rather than use resistors I just put more fans in to 'spread' the load.  however just like with my PC I hear a snail walking from 100 yards. lol.  The PC has had the treatment too Artic fans and CPU cooler. (Its a very old P4 prescott so was quite noisy, but its pretty fast.  Surprises my friends with their all singing an dancing machines when my oldy 2005 machine outpaces theirs with no mods other than the cooling. lol

To be honest I hardly ever have the fans on with he luminaire.  Large area inside etc.  When I get some cash though I may buy some quieter 50mm ones just in case they are deteriorating wuicker due to me not having the fans on 

Anyways nice neat job. Will still outpace a flouro setup of double wattage.

AC


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