X-10 Dimmable LED moonlight!

Playfair

Premium Member
With all the buzz about LED lighting, especially for moonlight (very cool looking, BTW!) what was lacking was a way to dim these lights via X-10 lamp modual through a controller.

Since the moduals Triac only works on resistance, the trick was to run LEDs off AC line voltage without a reduction transformer. I did this by using sizeable resistors (one to limit current to the LEDs, the other to "fool" the lamp modual since it needs a "load" in order to turn off). The resistors do burn off about 2 watts of power, so they get pretty warm.

Parts list:
-10 Blue LED's (Mine came from Allelectronics.com)
-6000 ohm 5 Watt resistor
-3900 ohm 5 Watt resistor
-Full wave bridge rectifier (this makes the leds blink at 120hz instead of a noticeable 60hz)
-1/4 amp fuse (pretty important due to light guage wires)
-wiring and connectors

Here's the wiring schematic of the "powersupply":
LEDschematic.jpg

Since the lamp dimmer only sees resistance, so it has no problem chopping the AC waveform to dim the circuit. The LED's themselves are simply wired in series, all 10. I choose to have to "blocks" of lights (one on each end of the tank), but they are still in series. I used 1/8" black plastic pieces and heated the leads of the led's so they could push through it forming their own "sockets". The soldering was done from behind, then another plastic piece was hot glued over it. There's enough lead on the LED's such that they can be bent to highlight different sections or corals in the tank.
Here's a pic of the finished "kit"...
LEDkit.jpg


Here's what one light bar looks like after being attached (I love "servo tape" from your local RC hobby store!)
LEDinstalled.jpg


Finally, here's a 2sec exposure of the tank lit by the lights during full moon. It's probably just a little dimmer than the 15watt blue party bulb I have been using, but it's a much nicer light. :D
LEDnight.jpg


Total parts cost was about $25, not including the lamp modual ;)
 
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NIIICE! :thumbsup: I wish I had as much free time as you do!!! lol

May do this in the meantime till I build a funky simulator.. :)

Oh BTW.. deleted your DP.
 
Looks nice playfair, thanks for the info. What do you have the x-10 hooked up to? Aquacontroller, Octopus? How far can they be dimmed? I was under the impression that you could only dim LEDs a little less than 50% before they won't light at all.
 
Way cool :smokin:

Does it dim as well as the party bulb? I have been using a 15w also but like your setup!
 
Jersey- I broke down and got an Aquacontroller... After 4 years of timers, I can't seem to stop playing with this thing!

As for dimming, it will go 0-100%, just like an incandescent lamp. Before the 6k resistor was added, it would only go to about 50%.

Discus, let me know if you don't find anybody ;)

DJ, no free time here! But once we get an idea... you know how that goes!
 
I say this knowing I am probably wrong and nowhere near an expert on LED's and electronics. Is it not possible to eliminate the flicker all together by adding a diode cluster- basic 4001 type- to seperate the AC current into DC current. I seem to recall that if you put 4 diodes in a certain pattern you seperate the positive and negative into their own independent pathways. I suppose it is inconsequential as 120hz is probably unnoticeable and perhaps the DC current termination will not work well with your x-10. Good work David!
 
rvitko said:
I say this knowing I am probably wrong and nowhere near an expert on LED's and electronics. Is it not possible to eliminate the flicker all together by adding a diode cluster- basic 4001 type- to seperate the AC current into DC current. I seem to recall that if you put 4 diodes in a certain pattern you seperate the positive and negative into their own independent pathways. I suppose it is inconsequential as 120hz is probably unnoticeable and perhaps the DC current termination will not work well with your x-10. Good work David!
I think what you are recalling is a recitifier, which is in the diagram albeit in block format. I will attach a full-bridge rectifier so you can see it's function beyond the block diagram.

Nice design, I've been thinking about using LED's for moonlighting also. I also found some blue-white LED's that have a 1000mcd rating, haven't done anything with them yet though.
 

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nice idea but one concern.

There is no isolation between the 120volts and the low voltage side of the set up, not ideal above a saltwater tank.

As to the flicker you would need to get the ac component of the supply to the diodes. A full bridge rectifier will not do this allone and you would need capacitive smoothing or similar to avoid flicker.
 
I think I was unclear about the "flicker". The first proto used reduced voltage AC to run the LED's, but since they only lit during half of the wave form, they flickered at 60 Hz, with a 50% duty cycle. The bridge rectifier detailed by xeon brings the negative part of the AC cycle back up, so the flicker is now at 120 Hz, which is the same as any AC lamp, including our MH and VHO driven by magnetic ballasts. Not noticeable.

As far as AC over the water, the 3900 ohm resistor brings it down to about 35v at 20ma, which isn't enough to even be felt if you touch it. I do plan to goop a little silicone around the LED leads once they are in the ideal positions, just to prevent SW from shorting any out.
 
Playfair,

If the LEDs get in contact with the water, up to 30 mA will go thru the water or you. 30 ma is a "threshold of respiratory paralysis", . It is safer to use a cheap ac / dc isolated transformer ( like the one you may have from an old cell phone). A nice aquarium night light is not worth this risk.
 
Good points george, except an isolation transformer will burn out the dimmable X-10 lamp module. It's a noble cause to reduce the risk of AC near our tanks, but that would require low voltage fluorescent and metal halide lighting, wouldn't it? I guess like our other lights, it's best not to let them contact the water!
 
Playfair,

You are right about 120 Volt all over the tank. I catch myself debating both sides. The reason I made this remark is because the safety was brought up and discounted later. I just wanted to remind the guys that it is still electricity and we should treat it with respect.
 
I just put together a similar LED moonlight. Instead of using multiple smaller LEDS I chose to go with a 1W LED. This puppy draws about 350mA, and is way too bright to look directly at. If not dimmed this thing will light up my entire 75 gal. tank well beyond what the moon would do. Another nice thing about the LED I chose is that it is 455nm rather than the typical 470nm for blue. This makes it a very deep blue, almost purple, that looks great at night.


FYI...the most efficient way to dim LEDs is to use a PWM circuit. Unfortunately, I haven't played around enough yet to get my dimming automated, through either x-10 or a PC. Hopefully soon.
 
I found all the parts,built the moonlight following the schematic and couldn't get it to work blew a couple of fusesone way and got nothing another (the leds are still ok). So here are a couple of questions:

Is the fuse and the 6k 5 watt resistor in parallel or series looks like parallel according to the schematic.

also maybe I have the POsitive and neg going into the wrong points into the rectifier The way I am reading this is that the positive goes into the "bottom" of the reactor if viewing the schematic. and negative on "top"

Has anyone else built the moonlight successfully and could offer up some guidance.

thanks for the help!

Mark
 
Mark,

There is not a fuse in the schematic. The ~ with a circle around it represents the AC power line, not a fuse.

The top and bottom of the rectifier are hooked to the hot and neutral of the AC line. These should be marked with 2 ~'s on the rectifier. The right hand side of the recitfier is the positive output which hooks to the positive terminal of the first LED, and the left hooks to the negative terminal of the last LED.

Hope that helps,
Michael
 
I guess it's possible to be blue and happy at the same time!!!

Thanks for your help karma that did the trick.


now I will be able to enjoy my tank 24 hrs a day... well except on new moon nights:)
 
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