The Puffer Forum

Nothing beats the soft glow of moonlights over your aquarium at night. (Well, that's assuming you're a hopeless aquarium geek with no life, like me). In this thread, I’ll not only show you how to make basic moonlights, but how to make nice adjustable-brightness bling bling moonlights with a built-in digital timer and that vary in brightness according to the phases of the moon!

We’ll start off simple, and work up, adding to the project a piece at a time, to make it so easy to follow that even your weird Aunt Agnes (the smelly one that always wanted to kiss you as a child) will be able to make one.

Q: Why use moonlights?
A: First and foremost, aesthetics – the gentle illumination allows us to see all the nocturnal activity without disturbing the inhabitants. Secondly, moonlight is natural! Many organisms seem to base their activity patterns on the phase of the moon – especially in saltwater, where mass coral spawning events can be governed by the phase of the moon. Plus, they are cool!

Q: Will it disturb my fish?
A: No, not if you don’t make it too bright. Moonlight is natural, after all. Maybe you’ll encourage your pufferfish to spawn, and be the talk of the TPF forums!

Q: Why are moonlights always blue?
A: Higher frequency light penetrates the water far more readily than lower frequency light. This means, as you travel deeper, blue light is more dominant than reds and yellows. So, blue is more natural! Additionally, blue light will be more efficient, and brighter, as it will be transmitted through the water far more readily. Plus, blue is cool!

Q: Can't I just buy LED moonlights off eBay?
A: Well where's the fun in that? Seriously, if you follow the steps of this tutorial through, you'll have a highly customised, INCREDIBLE, KICK-A$$ BLING BLING moonlighting system that will make you the talk of the town. People will be queuing up at your door to gawp at your tank. Can't get that off e-Bay.

Q: What the *&$@’s with all these Q&A???… I don’t want to read this! I want to build something!

OK…. Sorry…. Stay tuned for part one...Simple DIY moonlights..... Coming soon! Watch this space!!!!

Yes, the waiting is over!

Part One: Simple moonlights

You really don’t get much more simple than this!

What you need:

• Bright blue LED(s) (1,200 – 2,000 mcd is good) – A few cents
  Resistor(s) – less than a few cents
  12V Power Source [“wall wart� is fine, or a little switching PSU] – a dollar or two
  Housing – a dollar or two
  Piece of wire – nicked from something else (free)
  
  
  Having moonlights that will make your tanks look so cool your fish will hold parties in your honour – PRICELESS!

Oh --you’ll also need a soldering iron & solder – hopefully you already have this!


First thing you need to do is decide how many LEDs you want to use. For small tanks (10 – 20 gallons), 1 – 2 should be enough. It may take some experimentation to get it “just right�.

I prefer bright, 5mm LEDs. eBay is a great source for these.

Next, you need to determine the value of the resistor(s) to use. If you just connect up an LED, or string of LEDs to a power source, they will not last very long – they’ll likely burn very brightly for a short while, before burning out. This is because they’re unable to regulate the current passing through them. The job of a resistor is to restrict the current. So, by placing a resistor before or after an LED, you’re creating a current “bottleneck� that slows down the current to something the LED can handle.

The maximum current most LEDs can handle, without having their life shortened, is 20mA


The equation to determine the resistor value is

R = (Vs-Vled)/Iled

Where Vs = Voltage of the supply
Vled = Voltage dropped across the LED(s)
Iled = current passing through the LED(s)

The good news is that we know most of this…. Vs = 12V, and Vled is usually given in the datasheet for your LEDs. However, Vled for blue LEDs is usually less than or around 4V, so 4V is a good number to use if you can’t get your hands on the specs. As above, Iled = 20mA (0.02 A)

So, for a single LED, R would be (12V-4V)/0.02A = 400 ohms.


There’s no such thing as a 400ohm resistor, so you need to choose the nearest higher value. 420 ohm or 470 ohm would be fine.



For two LEDs wired in series, the voltage drop is doubled. Hence, R would be (12V – 8V)/0.02A = 200 Ohms. So a 220 ohm resistor would do the trick.



For more than two LEDs, you can just repeat the 220ohm resistor – LED – LED unit above, and wire each unit in parallel. Here’s an example for a four-LED circuit.



The next step is choosing a power supply. You need to pick one that supplies 12V DC, and enough current to comfortably power all your LEDs. The current your circuit will draw depends on the layout of the LEDs. Each unit above, whether one LED or two LEDs in series, draws around 20mA. For each unit you wire in parallel, you add another 20mA. The sum gives you the total current the moonlights will draw:
So:

• 1 LED: 20mA
  2 LEDs: 20mA
  3 LEDs: 40mA
  4 LEDs: 40mA
  5 LEDs: 60mA
  6 LEDs 60mA
  Etc….

My power supply does 1A… so plenty of room. Likely you will not have to worry about it unless you’re using a massive array of LEDs.

A regulated power supply is best, as the voltage will be constant, even if you are not placing a heavy load on the power supply. If you think you’re going to follow this tutorial through to the advanced stages (programmable phases, controllable brightness, etc), then it would be a good idea to go 50% over spec at this point.

From here on in, I’ll just focus on a two-LED system. I will be making this for my nano tank.

STILL got questions about LEDs? THIS site explains it all far better than I ever could.

Coming soon: Building the darn thing.... yes, and no worries, it gets more exciting, too!

Well that was all very boring wasn't it? All that reading, and we still just have a pile of components.... What next?

Preparing the LEDs

Super-bright LEDs tend to have a very narrow viewing angle. This means they will put a bright blue spot on your substrate! Cool if you want to make a Fish Disco, or blind your fish, but not the effect we are looking for here.

To fix this, it’s a simple matter of sanding down the clear casing with a bit of sandpaper. This serves to scatter the light as it leaves the LED. You don't have to sand the LED flat, just lightly sand some grooves into the clear casing, to make it diffuse the light a bit.

Take care not to bend the leads too much when sanding. You get extra points if you manage not to sand off your fingers while doing this!



Wiring the little b***ers up!

Time to break out the soldering iron!

LEDs can only be connected one way round – the long lead is the anode, and is connected to the positive, or +12V wire from your power supply, while the short lead is the cathode, and is connected to the 0V wire.

Once you’ve figured out which way they go, it’s a simple matter of soldering the LEDs together – facing in the same direction, with our resistor at one end. For larger arrays of LEDs, you may want to use a prototyping board, for neatness, and to hold everything in place. Once you’ve done this, then you can solder a wire onto each end.




Finishing up

I mounted the LEDs by drilling holes in the enclosure, inserting LED holders, and then securing with hot glue.

Remember, if you’re going to use LED holders, you might have to thread the LED holder onto the LED legs *before* you solder!! Trust me, I've learned this tip from experience!

I didn’t mount mine dead-centre, due to the way I plan to mount them in the canopy.



Snip off the barrel connector from the power supply (but you might want to save the connector, with a bit of wire attached, for later ), and solder the power leads onto the wire ends. Make sure you get it the right way round (don’t worry too much – if you get it wrong, nothing bad will happen… in fact nothing will happen at all until you resolder them the right way round!). Many “wall wart� power supplies have adjustable polarity, so in that case it’s just a simple matter flicking a switch to exchange the +12V and 0V wires.

Protect each wire join with electrical tape or heatshrink so that the wires can’t touch.

There… finished!




Once you’re satisfied with the work, you can turn it on!



Pretty bright!

Plugged into a timer, you can set your moonlights to come on when your main lights go off!

Too simple for you?! Waaaa, where's all the "bling bling" I promised? Well, in the next instalment, I’ll show you how to make your moonlights MUCH BRIGHTER without adding any extra LEDs!! *AND* be able to adjust the brightness at the touch of a button!

Until next time!

This is the kind of stuff Puffer-Mike likes to potter about with. I was hoping maybe you could show a picture of the intended effect, just to reassure mums, wives and girlfriends, or is that not within the rules?

Could the last pic in signature be entitled: "view from human 'tank'"?

Of course.... It would be great if Mike wants to have a go.. all these things can be ordered from Maplin.

Yes, the last pic is the view from my flat over Shanghai.

It's been really hard to get pics of the effect. Maybe I'll try again in a few days.... didn't want to get the tripod out.

The first pic is with the lights pointing directly down into the tank... it's actually too bright. However, for some reason, the camera wouldn't focus, even with a torch (flashlight). But you can see the relative brightness.



The second pic is with the lights shining over the top of the tank. This si the effect I was looking for: when the room lights are off, a shimmery blue light appears over the water. It's actually brighter than the camera makes out, but not too bright.

OK, I can imagine the effect. To get an accurate impression you would probably need a night vision mode camera, or something.

But that brings me to the next question, where would the moonlight be attached to? and at the risk of sounding very silly, are there any fluorescent Puffers?

I found this puffer called the Golden Guineafowl puffer on this page. It looks flourecent.



Edited by Jhong on 14 Nov, 9am. Please do not post copyrighted pics without proper references.

WOW! What a bright Puffer!

This sort of thing just makes me impatient to get my mini reef going.

This stinkin' 29G tank is just SITTING there, TAUNTING me, from underneath my kitchen table and alas! I still have no reef. It hurts me, that I do not have a reef in my tank.

But when I do, I'm posting pics like mad, and I'm makin' moonlights. Sweet tutorial - I totally want to makes some myself.

puffermama wrote: But that brings me to the next question, where would the moonlight be attached to? and at the risk of sounding very silly, are there any fluorescent Puffers?

You can attach them any way you like -- to the canopy, resting on glass covers, whatever. I'll post details of how I plan to attach mine later.

As for the fluorescence... that is one COOL-looking fish, but these moonlights are not designed to show fluorescence. Blue LEDs have a very narrow wavelength. UV LEDs would do a better job of bringing out fluorescence.

Sari wrote:This sort of thing just makes me impatient to get my mini reef going.

This stinkin' 29G tank is just SITTING there, TAUNTING me, from underneath my kitchen table and alas! I still have no reef. It hurts me, that I do not have a reef in my tank.

But when I do, I'm posting pics like mad, and I'm makin' moonlights. Sweet tutorial - I totally want to makes some myself.

Thanks! No harm in making them in advance ... And when you do get your reef set up, we look forward to seeing all the pics in the marine tanks forum!

So,

Is anyone still here?

Who's with me, ready to take this to the NEXT LEVEL?

I'm watching and definately interested.. thank goodness you posted pictures of the parts because I had no idea what a resistor and housing were... When it comes to electricity I run the other direction. Though I'm learning!

Yeah, I understand... It's all foreign until you actually see it in person. Thing is, it's all pretty simple when it boils down to it.

Any other takers ready for moonlights on steroids?