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DIY Moonlighting


evilknieval69

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I would try and do it with a voltage divider, basically you put 2 resisitors in series making one have the voltage drop you require and just tap your leds straight off the resistor in parallel therefore they would have the right voltage over them.. You would then have less components and therefore less power usage from your small supply..

I am not sure why you want to do this. There should be a fixed voltage drop over the LEDs so you only need 1 resistor in series with all LEDs in paralel.

See you want to have 5 LEDs of 3.3V 20mA paralel. For the calculations this means that you have the same as 1 LED of 3.3V 100mA. Of you have a 9V power supply then the resistor would be 5.7V 100mA. This wouls mean R= V/I = 5.7/0.1 = 57 Ohm (round up to 68 Ohm for available resistor). Take in consideration the wattage needed here is P=I*I*R = 0.1*0.1*68 = 0.68W. If the wattage is too small the resistor will get too hot and burns out.

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Instead of LEDs why don't you try 12V cold cathode fluorescents (CCFL)? They come in a range of colours. Their output is low (a few watts) but for moonlighting it could do the job.

I tied a UV CCFL but the output was too low, even for my 80L tank.

You could even use low wattage (5W) 12V tungsten halides. If you use ones with reflectors you can direct the light. I use 'naked' (no reflector, just bulb) 12V "ultra white" halogen (40W total) to light the tank. Simple easy to install and only 12V for those who get nervous hanging 240V over a tank of water! My plants grow ok, but I don't have anything fancy (Swords, Val & something else which I don't know what it is). They occupy very little space (I have about 25mm headspace). I'm also playing with some bi-pin 12V compact fluoro's (direct replacement for halogens) to up the colour temperature of the light, but they haven't proven very reliable.

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ok so i have been slack and not got around to wiring them but i have started :D:D:D

ANYWAY...

i am wondering, which way do i wire in the resistors?? they have three(i think) coloured stripes on one end, i was wondering if the striped end goes closest to the LED or on the other side away from the LED. i have it set up so i have the postive wire going to the striped end of the resitor, through to the positive side of the LED then through to the negative wire. is this correct. in the attached pic you can see what i have done.

this is a sample pic of what i have at the moment

ledwiring.jpg

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