Metal halide/led hybrid build

[spoon]

So after running  LEDs  for  years,  I decided I liked the  look  of metal halide better.  The  shimmer lines it  creates  along  the  tank  are  awesome and led  is only  just  starting to  come  close  with  units  such  as  the  kessil that  use a closely packed  array of LEDs.  Most  commercially available metal  halide  systems use  to or  Pl tubes  for  supplemental light  such  as  actinic light.  While  this  works  fine  it's heavy on power  use and not  as  customisable  as  led. There  is also  having  to  replace  the  fluorescent tubes as well  as  mh bulb  around  every 9 months.  So I set  out  to  have a play  with  making a hybrid of led and metal  halide. 

I had  a spare shop fitting  150w metal  halide with  a good  German electronic ballast  which  I decided  to  remote  mount  to keep  the  weight  of the  light  unit down.  I used  a 15000k bulb  in this, quite a crisp  white.  

I decided on 2 channels of 20w each  for the  LEDs and purchased cheap  20w  drivers,  an assortment of cree 3w LEDs, 2 heatsinks,  4 fans and  a mix  of 60° and 120° lenses. 

I decided to  cluster  the  LEDs together as tight  as  I could and Mount  them  as close  to  either side  of the  metal  halide  fixture as I could. This  was  because  I intended  on using  led  colours  like  red  and cyan that  do  not  blend well  with other led  colours.  And I wanted  to  minimise  the  "disco"  effect  apparent with  a lot  of led  units (  multiple coloured shadow  casts). 

Drilled  and  tapped  the  heatsinks to mount  led  stars  using m3 nylon  screws,  I used  a thermal  grease  on the  back  of the  led  stars.  I then  soldered up LEDs and tested  them.  First  time  I had  2v on the  heat sink ,  I traced  this  to  a tiny  bit  of solder dribble that  I cleaned up.  2v  may  not  sound  like  very  much  but  when it is at  a constant current of 600ma it  can  still  give  you  a decent  belt.

This  build  being  a few  years  ago  I can't  remember  all  the  specs of what  I used,  but  some  of the  led  colours  included cyan, red 680lm,  Royal  blue,  blue,  uv389nm, neutral white.  The  LEDs  were  wired  into  2 channels one  was  white  red orange and blue  other  was  cyan, uv  and blues Royal blues. All  LEDs  were 3w  cree (maybe  a couple of bridgelux) on 20mm stars. Each  channel had  a separate  driver  and power  cord. The  drivers  were 600ma with  LEDs  in series,  they  worked out  being  slightly underdriven. 

Since  this  was  my  first  play  around  with  3w  LEDs  I didn't  bother  with  dimmable drivers or high quality equipment or  go  as  far  as buying  specific bin  number  LEDs.  I didn't  even  put  an on/off  switch on it,  opting to  instead use a 3 socket timer I had already  to  turn  it  on and off. 

I made up  a metal enclosure using  galvanised louvre panels and welded  up  an  aluminium  frame  so it  could  sit  on the  trim  on the  top  of my  tank.  The  enclosure ended  up  pretty ugly  looking but  functional.  After  a bit  of testing with  an  infrared thermometer I was  happy  enough  with  heat  levels  to  be  happy  to  use  it.  Got  it checked,  tested  and tagged  at my  wife's  work.  Coral  growth  was  similar  to  the  previous led  unit  I was  using  but  I was  a lot  happier  with  the  colour  of the light  and the  metal halide  shimmer.  Despite trying  to minimise  the  disco  effect  it  was  still  slightly  apparent especially when  metal  halide  was  turned  off.  After  around  6 months  old scrapped  it  to  try  making  a new  unit  in a better  enclosure which  I'm close  to  finishing  now.  

[spoon]

Here  are  some  photos 

[alanmin4304]

Great work as always.

[fishyNZ]

nice. did you use active cooling as well?

Edited: sorry missed the 4 fans...

Edited May 14, 2016 by fishyNZ

[spoon]

Yeah sorry about that I only  have  limited photos  of  the  build,  but  used  4 cheap  CPU fans 2 on each  heatsink.  Turned  voltage down on a small  power supply to  about  10v  so  they  weren't so noisy