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Discussion Starter · #1 ·
Just got done fabricating LED moonlights for my hoods. I started with a strand of 50 5v LED Christmas lights, obtained from K-Mart's after-Christmas sale for $2.50. It has a pair of built-in 2k ohm resistors, one on either side of the light strand. Schematics will be posted tomorrow. I cut 12 LEDs in from the prong side, and cut the extra wire coming out of the third LED. I then added 4k ohm more resistance. I probably added too much resistance, but I wanted them to be a bit dimmer since I'm using 12. They are temporarily pressed between the reflector and frame of my light hood, I am going to angle them better tomorrow.

Total cost of this mod was: $2.50 for the LEDs, $5.00 for the resistors, and $1 for the Guinness I drank while soldiering everything together :D
 

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Here's a schematic of my final circuit. The doc that came with the lights said the LEDs were 5V. Use at your own risk. :D



Brandon, yes I have plants. ~12 stems of anarchis, ~10 java fern, a red leafed sword, and an aquatic onion looking thing. These are just nightlights and are not meant to light the tank during the day; for daytime lighting I have a pair of 15W aqua-glo bulbs and a pair of 10W CF bulbs I recently added.
 

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Jaysn said:
Here's a schematic of my final circuit. The doc that came with the lights said the LEDs were 5V. Use at your own risk. :D



Brandon, yes I have plants. ~12 stems of anarchis, ~10 java fern, a red leafed sword, and an aquatic onion looking thing. These are just nightlights and are not meant to light the tank during the day; for daytime lighting I have a pair of 15W aqua-glo bulbs and a pair of 10W CF bulbs I recently added.
LEDs are actually around 0.7 volts each. You pull the remainder of the voltage down through the resistors. There is very little current flow so the resistors should not get hot. LEDs are designed to run on DC current though. They only light when the current is running one way, when the polarity reverses, they do not light or conduct. Therefore your LED's are flasing 50 times a second (as does a fluorescent tube) I would be inclined to use a low voltage DC transformer to power them, even if they were not over a tank of water. Actual voltage is not critical. The resistance need not be this high either. Anything over about 330 ohms is sufficient. You could use a variable resistor of say 1K in series with a 330 ohm resistor and use it as a dimmer.
 

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nice idea on the fabricating, should of been put in parrallel tho, christmas lights arent designed to be used for 365 days a year i dont reacon, what type of amps do u pull from ur outlets in america? here we have 240 operating at 50 hertz.1 thing i know is that if 1 blows they all blow and thats the end of ur LED show case and a day of fabricating, if u wanna run it in parralel u should of done this
1) use a dc transformer to the operating voltage of the led lights
2)(diagram)say they operate on 24 volts

+24 +___________________________
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O O O O O O O O O O O O
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- ___________________________


this shares the same voltage but lowers the amps where as in series u lower the voltage being the LED acts as a resistor each light, thus lowering the voltage so the end ones r less dimmer then the starters
 

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You're best off setting them up in a combination of series and parallel. If you put them all in series like you said, you're running 24V across each. Typical LEDs only need 3.5-3.7V, so you have to suck up the rest into a resistor to get 20mA current (typical).

Also, for every parallel leg you add, you're adding current. Assuming you're pulling power from the wall, your voltage is set and you're basically charged for the current you pull. If you have the suggested current going through the LEDs (20mA), with 24 LEDs in parallel, you have 480mA. Way overkill considering you could do it in 40mA.

I just put a few LEDs on my 10g tank as well... mostly because I was bored and wanted to know if I could do it. I think I'm going to do it to my 29g tank as well and can document it if anyone is interested?
 
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