Just in my learning stage at the moment like a lot of other people, have a 4x2x1.5 tank which I am currently setting as mixed reef, Pretty sure I'm going to go the DIY route. How does a spread like this look over such a tank? using 60 3W LEDs on 3- 10"x 11" heat sinks (or whatever ally I can grab from work)
Reef Discussion
A couple of quick questions Joshwaaaa:
- Do you have any braces across the tank. If so, where?
- How high above the water will the LED's be?
- Are you planning on using optics?
- What are you planning for actinic as Royal Blue covers the required spectrum
David Sexton I think this is sort of what you are thinking of doing:
Picture borrowed from http://www.masa.asn.au/phpBB3/viewtopic.php?f=49&t=226744
Picture borrowed from http://www.masa.asn.au/phpBB3/viewtopic.php?f=49&t=226744
for my sink i have one to scrap metal yard got 2 peices of ali from a shop fitting door 110mm wide and about 4omm box cut them to 1100 long and now have had 15 lights running on there for just over a hour as a test before putting the rest down and i can only just feel a litttle heat comming into it now so with the 6 fans i have bought off ebay for $4.50 each new should keep cool i think;)
Pondering it at work I completely forgot about bracing, whoops :unsure it actually has a 150mm center brace so I suppose I have to rethink that one. But yeah aiming for around 150-200mm above water level however it will be adjustable as it will be hoodless. Optics I was leaning to 60's on the blues and whites which I think should give enough spread front to back, the actnics were more so just to bring out color in the corals as from what I have seen they really make the colors pop but I suppose the royal blue would do a good enough job of that?
Never heard that of the reds before, interesting. Only seen a few fixtures using them before. Maybe dont bother with them? just add a few neutral whites instead of the warm?
Will have to have another play with it at work when I'm bored tomorrow see what I can come up with
The RapidLED instructions talk about winding down the output of the drivers because 1.3A would be too strong.
A couple of questions aren't really addressed in their documentation:
- What should we wind them back to? (I went off 720~mA)
The instructions talk about using a multimeter to determine what the current is when you're adjusting the dimmer. It uses an example that suggests using another person to assist with wiring the multimeter into the LED circuit to determine the current, which is fidgety if done alone (I soldered probes temporarily to do this).
- Is it necessary to have a load on the drivers in order to determine the current they're pushing out, or would it be OK to just hook the LED + and - leads from the driver directly to the multimeter?
A couple of questions aren't really addressed in their documentation:
- What should we wind them back to? (I went off 720~mA)
The instructions talk about using a multimeter to determine what the current is when you're adjusting the dimmer. It uses an example that suggests using another person to assist with wiring the multimeter into the LED circuit to determine the current, which is fidgety if done alone (I soldered probes temporarily to do this).
- Is it necessary to have a load on the drivers in order to determine the current they're pushing out, or would it be OK to just hook the LED + and - leads from the driver directly to the multimeter?
Thanks for the questions David ;)
Yes, you do need a load on the circuit to be able to measure the current - and you need to hook up a string of leads before you measure the current, any less than the required number and you may burn out the LED's. This is not so important with the Meanwell 60-48P drivers as they automatically vary the voltage - the minimum voltage is 24V or 7 LED's.
They method you used to measure the current is quite OK i.e. putting the multi-meter in series with the LED's, but you need to make sure that none of the wires come adrift whilst the power is connected or you can blow the LED's. The major problem is that you need to disconnect a wire every time you want to measure/change the current.
An alternative is to put a 1ohm 5 watt resistor in series with the LED's. A wire wound one like this is best :
[Broken External Image]:http://www.parts-express.com/images/item_standard/015-1_s.jpg
Now, we will use Ohm's law of I=V/R where I=current, V=voltage and R=resistance. By using a 1 ohm resistor, R=1 which leaves us with I=V. Thus, rather than measure the current we only have to measure the voltage across the resistor which will equate to the current. This resistor can be left in place which means that the current can be easily measured at any time.
When you start, the current should be adjusted as low as possible by turning the variable POT fully counter clockwise - then slowly turn it clockwise until the desired current is achieved. Go slowly as this adjustment is very sensitive and a fraction of a turn can increase the current significantly.
What current should you use??
CREE XP-E's are rated up to 1 amp, with XPG's up to 1.5 amps. However, the CREE datasheet details, included the stated 50,000 hours life, are based on driving them at only 350ma.
There is a trade-off between lumens output, current and heat generated. I plan on providing more information in a future post in the DIY LED build series but the generally accepted compromise is around 750ma.
Hope this helps.
Yes, you do need a load on the circuit to be able to measure the current - and you need to hook up a string of leads before you measure the current, any less than the required number and you may burn out the LED's. This is not so important with the Meanwell 60-48P drivers as they automatically vary the voltage - the minimum voltage is 24V or 7 LED's.
They method you used to measure the current is quite OK i.e. putting the multi-meter in series with the LED's, but you need to make sure that none of the wires come adrift whilst the power is connected or you can blow the LED's. The major problem is that you need to disconnect a wire every time you want to measure/change the current.
An alternative is to put a 1ohm 5 watt resistor in series with the LED's. A wire wound one like this is best :
[Broken External Image]:http://www.parts-express.com/images/item_standard/015-1_s.jpg
Now, we will use Ohm's law of I=V/R where I=current, V=voltage and R=resistance. By using a 1 ohm resistor, R=1 which leaves us with I=V. Thus, rather than measure the current we only have to measure the voltage across the resistor which will equate to the current. This resistor can be left in place which means that the current can be easily measured at any time.
When you start, the current should be adjusted as low as possible by turning the variable POT fully counter clockwise - then slowly turn it clockwise until the desired current is achieved. Go slowly as this adjustment is very sensitive and a fraction of a turn can increase the current significantly.
What current should you use??
CREE XP-E's are rated up to 1 amp, with XPG's up to 1.5 amps. However, the CREE datasheet details, included the stated 50,000 hours life, are based on driving them at only 350ma.
There is a trade-off between lumens output, current and heat generated. I plan on providing more information in a future post in the DIY LED build series but the generally accepted compromise is around 750ma.
Hope this helps.
Members online
No members online now.