Cheap DIY LED fixture for Full QT

StirCrayzy

Well-Known Member
Well, OK disclaimer #1, CHEAP is Relative. I ordered extra hardware when I built my DT fixture, and I work in a prototype automotive shop where scrap materials are plentiful :) So when I say cheap, it's just the components I've purchased as cheap as I can find them. I'm sure a black box Chinese fixture can be had cheaper, but can you fix it for $3 if an led goes bad, or $30 if the driver goes out ? Probably not, and it'll take a couple weeks to get what you need from China. But I digress... I like building stuff, because it's fun, and I like my product to have a few mandatory requirements...
1.) Simple
2.) Quality components (exponentially compatible)
3.) Easy to repair
4.) Interesting design
5.) Fun to build

So I found some scraps around the shop that got my juices flowing, and I cut some radii to pretty them up. Poly carbonate splash guard on the left 1/4" aluminum base structure on right.

Ive wanted to build a QT fixture that could serve a few purposes. I have a 20g tall that currently has a 10g hood sitting on it sideways using a single CFL. and the salt air keeps shorting out bulbs which is very annoying. So I need a replacement, for new fish arrivals (not much demand for quality there), for emergency, and new coral QT ( slightly higher demand ) .
I placed an order with RapidLED for some goodies that I know will keep corals going strong at low power and shallow depth.

I'm open to suggestions and ideas, I also have a thought that I could use this as a full spectrum fixture if I build a Nano for my kids in the future. I haven't decided on mounting yet, maybe a slick little acrylic arm type , but not sure.
There are bronze bushings to use as spacers for the splash guard., and otherwise I'll be using all stainless hardware.


Now only 10 LEDs are to be used in this application (Layout below), which made me realize the list above was not entirely for this build, since the reds are for additional ATS light coverage on my sump. Also I might swap the cyans in place of the Royal Blues or Cool whites in this fixture, depending on what it looks like once lit up. Also I wanted a couple spares just in case. These are mostly compatible with my DT LEDs though terribly under powered in this application it gives a scavenging option if something goes wrong.
 
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StirCrayzy

Well-Known Member
On a side note, I'm shooting for passive cooling. I want efficiency, don't like noise, and don't feel like running an alternate power source to feed a fan anyway.
 

StirCrayzy

Well-Known Member
I narrowed the oval splash shield because the proportions were awkward.
Drilled and tapped to attach to the main plate, and mounted the spacers that will hold the driver on top.



Wondering if anyone has experience with heat transfer through painted aluminum. Most of my projects are left as bare alum, and transfer just fine. I may try and paint this to find out how it works. If it insulates too much, I will just dunk everything in thinner and clean it off, easy enough.
The LEDs will be bolted on, vs epoxy, to let me experiment with color options too .
 

StirCrayzy

Well-Known Member
Got the heart and soul in the mail today from RapidLED, and started fooling around with positions. Then I realized looking at it , to a casual observer this might appear to be destructive in nature... ?


Maybe I shouldn't be building this at work ...
 

StirCrayzy

Well-Known Member
Nothing final yet, but I've made some progress this week.
Thanks for tagging along I'll post some updated pictures later this afternoon of where the project sits at the moment.

The heat test failed with LEDs at full power so I've resigned to the fact that I will need a fan if I want to grow corals under this or at least quarantine corals. For fish quarantine purposes the fan will be switched off , and LEDs at 30%, but I came across a pretty cool $2 voltage controller that I'll be using to convert the 36 volt output of the driver into a 12 volt regulated output, which allows me to still maintain a single plug all in one fixture.
 

StirCrayzy

Well-Known Member
Aluminum turned into Swiss cheese thanks to the drill press


Tapped and bolted in the LEDs


Wiring done, (lit side anyway.)and It's ALIVE!



Currently Trying to figure out top side wiring and mounting
 

StirCrayzy

Well-Known Member
In a law ditch effort to dissipate heat, I scavenged a heat sink from an old Packard bell CPU. I cut it in half and epoxied to the top side, but still isn't enough to keep this little fixture cool enough to run passively.
Ideal temp for running LEDs is 90℉ as I'm told , and at full throttle I'm reading about 120, which is down 10° since adding the heat sinks. There's just isn't enough real estate on the plate to add enough to get me in the range.
I forgot to add the cost for the timer and voltage regulator was under $5 (eBay) . The fan connector came from an old computer as do most of he connectors I use on my projects, since they are plentiful, and common.
I programmed the timer today, and will observe some basic On/off cycles until I decide on fan size and placement.

 

StirCrayzy

Well-Known Member
If I want decent performance from the fans, I'll have to switch them on only as needed. So in a month, these should arrive from China and I can figure out how to wire them into the current fixture.
 

StirCrayzy

Well-Known Member
I bought a #4-40 tap and a drill bit to match it. I tap using a low speed air drill but I'd recommend hand tap for anyone trying it for the first few times.
I ordered stainless button head screws and nylon washers from Amazon for $10.
The nylon washers are critical , because tightening down onto the extra solder pads with screws, will cause a short circuit in the system.
 

StirCrayzy

Well-Known Member
Anyone who may be working with acrylic can drill and tap that also, and for low stress applications, holds very well.
I do so anywhere I can because its cool
 

StirCrayzy

Well-Known Member
China sent 5v fans, which sidelined full completion for weeks, but in the meantime I temporarily added a 5v wall wart ( left side ) wired to the 120v input on the driver. This allowed me to mock-up final placements /wiring, and test cooling controls.


One 30mm fan on each end, blowing inward. Wired together.


Here you can see the thermostat sensor epoxied to the bright side. (Silver cylinder w/ Black wiring)


Tank mounting cross members are bolted on , I decided to use this type of mounting for now until I think of something more exciting and adjustable. Carbon fiber struts maybe...




Mounted and wired electronics.


Wall wart removed, 12v fans are in, wiring finished, ready to go.



I have the thermostat turning on the fans at 34℃ /95℉, fans off below 32℃. So far I've monitored timing cycles, temperature, and thermostat cycles at work for a week, so it was time to take my new toy home to try out on the QT.
As it turns out, it's way too bright, unscientifical guess, of course. I'm running it at about 10-20% for QT.
Also it's a bit too blue for my taste, I may swap in a white. Done for now though.

 
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StirCrayzy

Well-Known Member
I forgot to add, power draw readings.
4 months in and no issues to report other than an algae bloom in the QT.

Low power for fish QT = 4w
Full throttle = 35w
 

cracker

Well-Known Member
Good job Stir ! Be careful where You post some of those pics . People who don't know might not understand. You will have the FBI knocking on Your door LOL
 
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