DIY moonlighting

Madmike · 08-27-2003, 11:04 PM

Here is a simple and cheap way to create a cool shimmering moonlight effect in your reeftank using superbright blue LEDs. Also, by wiring in a potentiometer you can adjust the brightness to your liking or adjust as necessary to make a moon cycle.

Shopping list

LEDs (I use 2 5500mcd LEDs over my 45 gallon hex, purchased from superbrightled.com at 1.30 a piece...part number is RL5-B5515.) Use as many as you see fit on a longer tank. Every 12" or so should be enough...these things give off plenty of light!

Resistors-1 per LED. Go to www.bit-tech.net/article/68/ and enter the supply voltage (on the power supply), LED forward voltage (on the package), and the Diode rated current (usually 20mA). the caculator will caculate the minimum resistor size, you can use bigger than that number, but not smaller...the bigger you go over the number, the less light the LED will put off.

As an example the LEDs i used were 3.5v, 20mA, and my power supply was 5.9vDC power supply from an old cell phone charger. This caculates out to 120ohm resistor...I used 220s available at RadioShack.

Potentiometer- I used a 5k ohm pot available...but a 1k ohm would have allowed more light and thus more adjustment, although mine seems to adjust plenty with the bright LEDs

Power Supply-An old DC cell phone charger anywhere from 4-12v will work just fine...just remember to adjust the resistor size to your power supply voltage.

Misc- extra wire and a soldering iron, led holders

Steps
1. Solder a resistor to the short end of each LED...be careful not to get the LED or resistor too hot.

2. mount the led in a convenient location in your canopy...I chose to mount mine in my halide reflector, others have used spare strips of acrylic or wood to mount the LEDs on the canopy.

3. Solder a wire from the other end of the first resistor to the next resistor and so on for as many LEDs as you have, this wire then gets connected to the negative side of the power supply.

4. Solder another seperate wire from the longer lead on the first LED to the next and so on for all of the LEDs, this wire then gets connected to one terminal of the potentiometer...it doesnt matter which one.

5. Connect the positive side of the power supply to one of the two remaining terminals on the potentiometer..again it doesnt matter which one.

Thats it! Enjoy your new moonlight!

I have to give all of the credit for this idea to DJ88 at Reef Central, he posted his idea...i just modified his directions to suit my tank best, as should you.
Mike

Madmike · 08-27-2003, 11:06 PM

here you can see the wiring along the reflector and potentiometer

Geoff · 08-28-2003, 08:32 AM

now that looks sweet. very small and unobtrusive.

being totally mechanically minded.

could you explain this part:

This caculates out to 120ohm resistor...I used 220s available at RadioShack.

are these LED's also available in red. i may do this for nightime viewing!

thanks,

G~

Madmike · 08-28-2003, 11:57 AM

A resistor is needed for each LED so they don't get too much voltage and burn out quickly. By using the "calculator" with the stats from the LED packaging and your chosen power supply you can figure out what size of resistor you should choose.

I think I am understanding your question right.

Did you mean why did i go with 220 instead of 120? If so it was because thats the smallest my radio shack had in stock

Yes you can get red LEDs, they make them all of the way up to 12000mcd, about twice the brightness of my blues!...that might be cool, you better try it and let me know if i need to change mine, or just add red and switch back and forth

Let me know if it works!
Mike

Geoff · 08-29-2003, 09:00 AM

still confused.

how did you arrive at a 120ohm resistor? what magic calculator did you use to get this number.

i want to see math. just do not know how to step down the voltages like this. i have always tried to find a PS that was rated the same.

if you want to use the LED's as a moonlight then keep it the way it is. if you want to use the LED's as a way to observe the critters at night then switch them out to red. i am thinking of adding red ones, so when my moonlight controller is sending newmoon signals and the tank is dark i can light it up and see who is lurking around.

G~

Madmike · 08-29-2003, 11:40 AM

the magic calculator is here,www.bit-tech.net/article/68/;)
but if you really want to do the math yourself the equation goes like this
V=I x R
V=voltage of power supply, in my case 5.9v
I=current in A, convert mA to A, in my case 20mA is .02A
R=resistance, the unknown...soon to be figured out

to use the equation you first take the voltage of your power supply, mine was 5.9v. A LED in my example takes 3.5v, so that leaves 5.9-3.5=2.4v accross each resistor. So for my example 2.4v is V and .02A is I. 2.4/.02=120ohms.

The power of the resistor can be achieved using P=V x I. so in my case P=2.4 x .02=.05watts so a 1/4watt resistor should be just fine.

Dont get me wrong, i use the magic calculator

, I had to go look up the equations

I don't think i want to switch out my blue leds, maybe just add a couple reds and switch between the two.
later
Mike

Madmike · 08-29-2003, 10:13 PM

just added red LEDs, will post pictures tonight when its dark.
Mike

Doug1 · 08-31-2003, 01:41 AM

Pics??????????????????

nos68 · 08-31-2003, 07:14 PM

Can you give me a ballpark idea of the cost of parts for this? Sounds interesting...

thanks,
Chris

Madmike · 08-31-2003, 08:08 PM

LEDs are about 1.50 to 2 bucks each, depends on how big your tank is.
Resistors are about .99cents for 5
wire, anything laying around, i used speaker cable-minimal cost
potentiometer-around 3 bucks, you only need 1
power supply-look for an old power supply for a cell phone charger or old game system, most are ac/dc converters. I had several laying around my place-worst case radio shack sells them for about 15 bucks.

so for my setup it cost 3 bucks for the LEDs, .99cents for the resistors, and 3 bucks for the potentiometer. total of 7 dollars

Mike

Madmike · 08-31-2003, 08:10 PM

oh, and the pics for the red LEDs will be here shortly, i found that you need to use more LEDs if you are using red, i will need about 4 over my hex to be able to see easily...with the two it looked cool but couldnt really see all that well on the sandbed

Mike

Geoff · 08-31-2003, 11:57 PM

that darn red wavelength just does not like to go through SW does it.

G~

Madmike · 09-01-2003, 11:52 AM

nope, going to get 2 more this week sometime when i have time, i don't think radio shack is open today...but the mall is, maybe i will have to visit the mall, my least favorite thing.
Mike

Madmike · 09-01-2003, 10:49 PM

And finally the Red LED pics...

Madmike · 09-01-2003, 11:01 PM

And the Blue...