So I got bored tonight. My LED Moonlighting.

[DJ88©]

5 3200mcd LED's

6V 800mA supply.

5 x 220ohm resistors wired to cathodes.

1 x 1Kohm pot for dimming(temporary till a controller is built)

three pieces of acrylic strip 3/4" wide for frame and shell.

Last shot was taken at full intensity on a four second exposure.

Really cool!!!!!!


http://members.shaw.ca/dj88/moon/led_1.jpg

http://members.shaw.ca/dj88/moon/led_2.jpg

http://members.shaw.ca/dj88/moon/led_3.jpg

http://members.shaw.ca/dj88/moon/led_4.jpg

http://members.shaw.ca/dj88/moon/led_5.jpg

[Dlckwood]

Very cool, what did you use to power the LED's?
DLCKWOOD:p

[DJ88©]

an extra 6volt 800 mA supply I had hanging around. :)

[musicsmaker]

How do you feel about the spotlighting effect you have going? I personally didn't like it on my tank, so I angled them to opposite corners. It spread the light out pretty even.

[Entropy]

I know you stayed up all night watching the tank under the new moon lights, so what did you see? :D


Very Nice!

[kentrob11]

Very cool!

[DJ88©]

so I angled them to opposite corners. It spread the light out pretty even

The "disco effect" was for fun. :D The LED's are now aimed at the lid of the hood. Nice even diffused or dispersed lighting. very nice. :)

I know you stayed up all night watching the tank under the new moon lights,

Actually I didn't.. :fun5: lol I wanted to. but had class this morning. ;)

Now once the final is done on friday. look out. ;) lol

[Racenrich]

Great looking night lights. I love the way it turned out, simple yet effective.
how much did this setup run you?
Any directions on how to do this?
I'd love to duplicate what you have there.
I have a 90g that it would look great on!

thanks and keep up the nice work!

RK :cool::cool: :cool: :smokin:

[DJ88©]

Cost?

ummmmm.. lemme think.

$5 for the acrylic. Scrap at acrylic shop

$3 ea for the LED's. (expensive up here)

$.10 ea for the resistors(probably less but guessing ;))

Power supply.. had it laying around. lol

$.50 for the Potentiometer (give or take)

my time.. Priceless. ;) :D

so say

$30 with taxes.

And you can find a power supply at any computer surplus store. They will have all kinds of DC power supplies for cheap.

As for directions.. Let me get home tonight and I'll make a neat little write up.

[jeff967]

sweet stuff, I might have to go down to the local rat shack, and look around.
thanks dj88, that rocks,
jeff

[DJ88©]

Quick construction directions. :)

Drill acrylic with 3/16th holes angled if you want. Countersink with 13/6th so LED fits in further.

Fit each LED in so they protrude out the other side. If they are loose put a drop of weld on over the end. When you fit them in have the Cathode lead pointing up(shorter leg).

Drill hole to fit potentiometer in. And two holes in the one end for wires to fit through.

Take red wire and solder it to the Anode of the furthest LED.(Long lead). String the wire along and strip a small portion of plastic off the wire so as to solder the LED as you move along. Keep the wire kinda taught.

Once the red wire is soldered to all five LED's solder the opposite end to the wiper of the Potentiometer.

Now take another piece of red wire and solder it to one of the otehr two legs of the Potentiometer. Feed this out of the stand to the positive of your power supply.

To each cathode of the LED's solder a current limiting resistor. I'll explain figuring out what one to get at the end.

Now take black wire and string it across from the last LED in line(off of the unused end of the resistor) and attach it to each of the resistors. Strip off a bit of plastic off to solder the resistor to.

Once all the resistorsa re connected to the black wire run this to the negative of your power supply.

In a nutshell you are done.

now for figuring out which resistor you need.

On the LED package find out what the Vf is. Forward Bias Voltage.

Find a power supply that is a higher voltage than Vf.

Next take the current rating of the LED and the Voltage of the LED and Powersupply and go to this site. http://www.electronics2000.co.uk/calc/calcled.htm

enter the Vf, If and V supply in the lower three boxes and hit calculate. that will give you the size of resistor you need.

DON'T buy a power supply that is the same voltage as the LED's. It is a PITA to explain how to figure stuff out then.

I'll try to get some pics later. to explain the soldering. dinner time.

[musicsmaker]

DON'T buy a power supply that is the same voltage as the LED's. It is a PITA to explain how to figure stuff out then. Shouldn't it eliminate the need for a resistor if you did?

[DJ88©]

Shouldn't it eliminate the need for a resistor if you did?

No. If you do that you will have nothing to limit the current being supplied to the LED. What will happen is the diode will forward bias(turn on) the powersupply will see little to no resistance and send an infinite amount of current. This keeps going until the diode blows.

You need a current limiting diode of some sort. The resistor does just that. It limits the current.

trust me on that one. Many LED threads are due to people doing what you suggested and blowing them when they didn't run a current limiting resistor.

This is the easiest way to do it. honest. It will save lots of grief.

But that is my opinion. Others I am sure will attest to other ways.

Running a bank of LED's in parallel like this is very easy to set up. little thought involved.

[Chamkeeper]

These Diodes have a HUGE forward resistance. I believe they will self regulate to an extent. I use a single diode on my 7g and played with it prior to installation. It seems they have no troubles with anything less than about 3.5 V. Personally, I agree with DJ, spend the change to provide some security. Also, for anyone setting them up in parallel, use one resistor for each diode. This will prevent a single failure from cascading.

[niko5]

Wow I cant wait to make one of theas for myself :) DJ if you get time why dont you take another picture of your tank with the different angle on the LED's ied like to see how the light looks reflected off ur hood.

[DJ88©]

These Diodes have a HUGE forward resistance.

Once a diode is forward biased(turned on) it's resistance drops to almost zero. It isn't zero but it is small. When reversed biased or below the forward biased region the resistance is huge. Diodes are in effect a check valve. Current moves one way not another.

There is a link in one of the LED threads that goes into depth how as a diode warms up it drops in resistance and in effect becomes a short circuit. I'll take a look for it.

In the meantime here is some theory behind Diodes and LED's.

http://engineering.dartmouth.edu/~engs031/hansen/demos/LEDs.pdf

As an aside.. Diodes don't self regulate. They will take as much current and voltage as you want to throw at them. Go too high above Vf and If and you will burn them out. With LED's this upper threshold is not very high. Depending on the LED it can be only a portion of a volt above Vf and a few milliamps above If. The higher you, go the shorter the lifespan of the diode. Too high and it blows.

[marm64]

You have to have a current limiting resistor. I have seen lots of LED's burnt out by somebody just checking to see it works or if all the digits in a digit work. It does not take much time to put too much time before there is too much current. I saw somebody in lab just touch the +5 volt wire to all the digits in a display and they worked and when he hooked up his circuit and it would not work and when he rechecked it it was burnt out.

[wpbfishguy]

What does a potentiometer do?????????

[DJ88©]

A potentiometer is a variable resistor. What it is used for is to vary the current in the circuit by increasing or decreasing the resistance in the circuit. By varying the resistance you also change how the voltage is divided up in the circuit.

long story short it is like the dimmer switch you have for home lighting.

[Awestralian]

DJ88, i think this is a great idea, and im loving it!
I dont suppose you'd whip up a small, simple wiring/schematic diagram for me (and everyone else) at all??
Sorry for the trouble, and ill understand if you are too busy to do it!
:D

[Stormbringer22]

DJ88, very nice! Do post schematics!

[DJ88©]

Been a bit busy this week. It is on my list of to do stuff.

But the final exam I have in two and a half hours has priorirty. :D

[Awestralian]

Completely understand dude.
Best of luck in the exam!!
:thumbsup:

[beemer]

Do you know if this will run the LED to spec. Why 6v 800ma power and why 220ohm resistors. I am asking because I checked with allelectronics.com they told me 12vdc 1a w/ 470 ohm resitors. Will your setup run the ultra brights? and if now how do you figure out how to run the ultra brights?
Sorry for all the dumb questions I am just electronicly stupid.
will your setup run this LED?
http://www.superbrightleds.com/leds/b2_specs.htm
Hey I know you all are busy just trying to figure it all out
Also I know what a resistor is what is a cathode?
Thanks ya'all
Jerod

[Team Slug]

Originally posted by beemer
Do you know if this will run the LED to spec. Why 6v 800ma power and why 220ohm resistors. I am asking because I checked with allelectronics.com they told me 12vdc 1a w/ 470 ohm resitors. Will your setup run the ultra brights? and if now how do you figure out how to run the ultra brights?
Sorry for all the dumb questions I am just electronicly stupid.
will your setup run this LED?


What DJ88 is running and what the guys at allelectronics.com told you are almost the same for all practical purposes.

For the LED you posted the link to you would probably want a transformer between 6-12V. To figure out what kind of current capbility you would need figure out how many LEDs you want to use and multiply by 20mA (the maximum current for these LEDs), i.e for the 800mA supply that DJ88 is using you could run 30 LEDs (30 x 20mA = 600mA, that gives you 200mA extra...you don't want to drive your transformer all the way to it's limit).

The size of the resistor depends on what voltage you pick for your transformer. The formula is V=I*R where V is voltage, I is current (in A not mA) and R is resistance. For example:

If you use a 12V supply, the LEDs drop 3.5V, that leaves you with 8.5V across each resistor (assuming you use a separate resistor for each LED). You want 20mA (.02A) to flow through each LED for maximum intensity. This gives 8.5=.02*R -> R=425 ohms.

To calculate the power, in Watts, of the resistor needed the formula is P=V*I or P=V*V*R...either one works. In this case we'll use V*I...V=8.5 (for the resistor from above) and I=.02 -> P=8.5*.02 -> .17W. You can safely use a 425 ohm, 1/4W resistor for each LED.

In this example make sure you don't use a resistor smaller than 425 ohms because it will make the current go up and can dmage the LED. A larger resistor is fine though. It will make the current go down and make the LED appear dimmer.

[DJ88©]

Team Slug,

Thanks! :)

I had a reply written and lost it.. sigh.. decided to go get some food and here you replied for me. :)

Thanks again.

[Team Slug]

Food's more important.:)

[DJ88©]

Yes it is.. now I am full and ready to think..

Start designing the PIC coding for this thing to simulate lunar cycles. :D

[Awestralian]

Start designing the PIC coding for this thing to simulate lunar cycles

:eek: :eek:

No thats cool!
:D

[beemer]

Ah finally a simple clear and CONSICE answer. Thank you very much. I am in the process of ordering the LED now. Looking to do just moonligh for now.
Has anybody experimented with the new UV bulbs. I wonder what effect that will have on corals.
Has anybody seed testing on these yet. How far will the white bulbs penetrate?
Thanks again team slug
jerod

[Team Slug]

Originally posted by DJ88
Yes it is.. now I am full and ready to think..

Start designing the PIC coding for this thing to simulate lunar cycles. :D

Yes...the benefit of using multiple LEDs. Are you going to have it simulate the moon tracking from left to right or just intensity? I haven't used a PIC in years. Does yours have PWM capability?

[DJ88©]

I have a few different ones here. Some with PWM and others without. That was how I was planning on doing the varying intensity.

I could go for overkill and use a 68HC12 on it. ;)

I was thinking of doing the tracking as well. All depends on how creative I get.

I have the summer off to do as I please.

[Louis]

Great thread!

I just finished my own moonlight and want to double check w/ everyone here that I did it correctly.

I used LED's from radio shack with the following stats:

Forward Voltage: 3.7 typ - 4.5 max
Forward Current: 20mA typ - 30mA max
Intensity: 2600mcd
Wavelength: 468nm typ.

I decided to use 2 LED's for my 10gallon nano, which I am powering with a 9v transformer I had laying around. I purchased 150ohm resistors ( I used the max rate numbers to calculate resistor size with the site mentioned earlier ) and followed the instructions described by DJ88. Is this sufficient for my 2 LED's? I noticed that if I use the typical numbers I get a much larger 265ohm resistor. I did purchase some 270ohm resistors just in case I need to switch them out.

Thanks again for the great DIY project and all your help.

I'll get some pics of my tank later tonight ;)

[Napalm]

Personally I would go with the larger resistor first. First off you will prolong the life of the led. Second it is ment to be moon lighting and with such a small tank you might have too much output when running the leds at their max. You can always go with a smaller resistor later. Just my opinion.

[Louis]

How can I determine if I have too much output? Will the change in resistors be noticable to my eye? I currently have the LED's pointing up and reflecting off a temporary reflector. They dont seem very bright and the light distribution could be better... Here are a couple pics so that you can see what the tank looks like:

http://www.surrealinnovations.com/saltwater/moonlight_01.jpg

http://www.surrealinnovations.com/saltwater/moonlight_02.jpg

[quiksilver]

thats tight. :D good job

[DJ88©]

Louis,

If you are wanting a more spread out look to the LED's, run them as you are but don't have a reflector.

As far as the resistors having an effect. You should notice the difference. As I vary the potentiometer in mine it changes from full brilliance to about 1/2 intensity.

[Team Slug]

Originally posted by DJ88
I have a few different ones here. Some with PWM and others without. That was how I was planning on doing the varying intensity.

I could go for overkill and use a 68HC12 on it. ;)

I was thinking of doing the tracking as well. All depends on how creative I get.

I have the summer off to do as I please.

You're right, the HC12 would be way over doing it...but then again. I'm using a simple PWM dimming circuit on mine and it seems to help with the LED temp quite noticably. PWM is definitely the way to go to extend the life of the Luxeons, and all LEDs for that matter.

[DJ88©]

I could use the HC12 and do some simple ADC for temps and as well control some DC fans etc. as well as the LEDs. Have thought about that one too. but, bit more $$$ if I decide to build these for others.

[Nishant3789]

Originally posted by musicsmaker
How do you feel about the spotlighting effect you have going? I personally didn't like it on my tank, so I angled them to opposite corners. It spread the light out pretty even.


actually if u angle it up at reflectors it akes a really cool effect... that might be a consideration.

[bvoss]

DJ,

I've got some super bright (10,000 mcd) LEDs on order. I plan to 4 in my 90gal and angle them into my PFO reflectors. I understand the resistor calculation but I'm not sure about the potentiometer. Does a 1K ohm pot sound about right to dim 4- 30ma LEDs with a 12 volt power supply?

Until you come up with a brilliant dimming circuit, I'll just play the role of Apollo and dim the "moon" by turning the knob every few days.

Thanks,

Bill

[Sealily]

So very slick! And beautiful, too. Excellent.

[Team Slug]

Originally posted by DJ88
I could use the HC12 and do some simple ADC for temps and as well control some DC fans etc. as well as the LEDs. Have thought about that one too. but, bit more $$$ if I decide to build these for others.

My mistake...I was thinking you wanted to use the HC12 for just LED control. Now it makes much more sense.

[Team Slug]

Originally posted by bvoss
DJ,

I've got some super bright (10,000 mcd) LEDs on order. I plan to 4 in my 90gal and angle them into my PFO reflectors. I understand the resistor calculation but I'm not sure about the potentiometer. Does a 1K ohm pot sound about right to dim 4- 30ma LEDs with a 12 volt power supply?

Until you come up with a brilliant dimming circuit, I'll just play the role of Apollo and dim the "moon" by turning the knob every few days.

Thanks,

Bill

Just make sure you have a fixed value resistor in series with your pot. Otherwise you'll burn the LEDs out if you turn the knob the wrong way...:mad:

[DJ88©]

I made this schematic then remembered I had put the resistors after the LED's. It doesn't make a difference. It still regulates the current flow through the Diode and will work fine as is.

http://members.shaw.ca/canreeftank/pix/schematic.JPG

[Team Slug]

Perfect little summary schematic. Nice.

[Awestralian]

Ah sweet.
Thanks :D

[niko5]

DJ,

I just want to make sure I get this right :).

It does not matter what side of the LED the resistor is on correct?

Thanks

[DJ88©]

Doesn't matter. :)

[niko5]

Any luck with your Lunar cycles module :)

[DJ88©]

lol no. that is number three on the list right now. Fan controller comes first. plus I am waiting for my order of new PICS to arrive. ;)

[The R/C Man]

DJ88,

Cool! After building my own stand, sump/refugium, siphon box and light timers I got lazy and bought a moon light. :D Did you ever think about an AC/DC adapter for the power source? You know, like the ones for hand held video games....... They run about $6. What do ya think?

[DJ88©]

That is the plan. a 6V supply. As long as they puch enough current(which I have no doubt they will).

If the 6V isn't enough for the PIC then I can go up to a 9V supply.

[Trickman2]

10 6000mcd Blue LED Bulbs
5mm standard, 3.5v.

Any Ideas on what resister I will need? Or power supply to run them? :rollface: Any help would be awesome

[niko5]

Hey DJ if you have a min I need some help im electronic impared haha more or less :P Anyway to my problem.. Iv got all the parts and im confused about my Potentiometer.

The box reads:

NTE Elctronics Inc.
502-0103
534-1-1-102
1K OHM
10 Turn/Linear
WireWound

Sticker on box:
1K OHM, POT-3 Watt 10
10 turn, precision wirewound, metal shaft.

Ok i hook it all up to my left with resistor 6 v 800 mA trans. The led comes on but no dimming when i turn the potentiometer. It has 3 contacts on the potentiometer iv tried it every different way and the same results.. did i buy the wrong part?

Also my led doesent seem all that bright.. should it blind u when you look into it? mine doesent haha the one the guy helped me pick out (according to your scematic) is a Linrose Super Bright LED Blue T1 Super bright blue LED and the back chart has 6v use a 220 OHM restor.. Does it sound like the right LED?

Thanks alot for you help sorry im kinda slow with this stuff :)

Thanks again

[banger]

Hi,

You might want to look at Varad hyper led light bars for cars. I just picked up 2 12" bars for $20 each. They have 12 leds spaced 1" apart, and run on 12 volts. I looked at the cost and time to build my own, and figured this was a pretty cheap and easy ay to go. They come with mounting brackets, screws etc, so they are pretty easy to set up. I have also started to work on a moon controller, which I hope to have done soon. Although I havent figured out the best way for setting the lunar cycle though. I could use either a generic moon cycle, or allow the input of latitude and longitude, and have it calculate the actual moon cycle for that area.

[Team Slug]

Originally posted by niko5

Ok i hook it all up to my left with resistor 6 v 800 mA trans. The led comes on but no dimming when i turn the potentiometer. It has 3 contacts on the potentiometer iv tried it every different way and the same results.. did i buy the wrong part?

Also my led doesent seem all that bright.. should it blind u when you look into it? mine doesent haha the one the guy helped me pick out (according to your scematic) is a Linrose Super Bright LED Blue T1 Super bright blue LED and the back chart has 6v use a 220 OHM restor.. Does it sound like the right LED?

Thanks alot for you help sorry im kinda slow with this stuff :)

Thanks again

If it is truly a T1 LED then it probably won't blind you. T1 is a smaller size LED. What you really want is a T1 3/4, which is 5mm diameter. Or better yet you can use one or two Luxeon LEDs and have more light than you will ever need.

[musicsmaker]

I could use either a generic moon cycle, or allow the input of latitude and longitude, and have it calculate the actual moon cycle for that area. I would use the latitude and longitude of where you live so that it works with the actual pull of the moons gravity.

[banger]

Originally posted by musicsmaker
I would use the latitude and longitude of where you live so that it works with the actual pull of the moons gravity.


Yeah, this would be ideal, the trick is finding a reltively easy calculation for this, since most microcontrollers arent very good at math. The other option is getting the base data from a web site, and enetering it into the microcontroller, then letting it generate the cycle from there.

[Biodragen]

I have been reading this thread and I am still unsure of what it is I need. More confused now than when I started.

I want to use 2-10,000 mcd led lights @ 3.2 - 5 volts.

This is all I have at this point for specs on these led's.
I do not know what else I need and how to figure it out.

What I do understand is I need a resistor for each led.

What I do not know is what power I need.
I have two laying around
one is : 60hz 15w
other is : 60Hz 6.5w

I would like to make two sets of these moon lights.

I need a parts list...the rest I can figure on what to solder where.

Brian

[TNDave]

[QUOTE]Originally posted by niko5

Ok i hook it all up to my left with resistor 6 v 800 mA trans. The led comes on but no dimming when i turn the potentiometer. It has 3 contacts on the potentiometer iv tried it every different way and the same results.. did i buy the wrong part?

Also my led doesent seem all that bright.. should it blind u when you look into it? mine doesent haha the one the guy helped me pick out (according to your scematic) is a Linrose Super Bright LED Blue T1 Super bright blue LED and the back chart has 6v use a 220 OHM restor.. Does it sound like the right LED?

Do you know what the forward voltage (Vf) of your LED is? Typically they are 3.2V to 4V. Also you need to know the forward current (If) of your LED to get the maximum brightness out of it. For a 6V supply and Vf of 4V, that is a 2V drop across the resistor you put in. To get 20mA out of a 2V drop, you would need a 100ohm resistor using this formula:

R = (Vsupply-Vf)/If

With your 220ohm resistor you are only putting 9mA through your LED (again assuming it's forward voltage is 4V).

Now, on to the pot. Is it INLINE with your 6V supply? If so, once you get the right LED resistor inline with each LED, you should see a dimming effect with the pot.

Good luck, hope this helps!!!

[TNDave]

Originally posted by Biodragen
I have been reading this thread and I am still unsure of what it is I need. More confused now than when I started.

I want to use 2-10,000 mcd led lights @ 3.2 - 5 volts.

This is all I have at this point for specs on these led's.
I do not know what else I need and how to figure it out.

What I do understand is I need a resistor for each led.

What I do not know is what power I need.
I have two laying around
one is : 60hz 15w
other is : 60Hz 6.5w

I would like to make two sets of these moon lights.

Brian

Brian,

See my response to Niko for properly sizing the resistor based on the forward voltage and current of the LED. The power supplies you have listed sound like AC output supplies, and you need to use DC output ones (like come with cordless phones, etc). What you should expect to see on the transformer is 110V,60Hz IN, and 6 or 9 or 12V DC, 800mA output. You can use any voltage transformer, so long as the voltage is higher than the forward voltage of your diodes, and it puts out enough current. Typically these superbright LEDs consume a max of 20mA each. If you are building a light with 10 LEDS, you would need a supply that could source 10x20mA, or 200mA.

Good luck, hope this helps!!

Dave

[chinaboy1021]

OOOOOOOOOOOOOOOOOOOOOOOOOOOOOMMMMMMMMMMMMMMMMMMMGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG????????? ???????????????????????????????

i dont know much about reefing, but im trying to learn on these forums. but your LED AMAZING!!!!!!!!!!!

OH WOW. how do i express myself. WOWOWOWOWOWOOW.

[Biodragen]

Ok I get the deal on the power supply
It is DC and it reads

4.5v .3a for one of them
the other one is 14v .7a

I looked up what is for 10,000mcd superbrights

These are 3.2 to 5v blue lights

So I looked up for the white ones and found the VR to be 5
and the Vf to be 4.0

Aslo I was not planning on implementing a pot.

So I could use my 14v supply with two led's and two 100ohm resistors.

Aslo which is the positive on the LED? the long end or the short end?

Brian

[TNDave]

Originally posted by Biodragen
Ok I get the deal on the power supply
It is DC and it reads

4.5v .3a for one of them
the other one is 14v .7a

I looked up what is for 10,000mcd superbrights

These are 3.2 to 5v blue lights

So I looked up for the white ones and found the VR to be 5
and the Vf to be 4.0

Aslo I was not planning on implementing a pot.

So I could use my 14v supply with two led's and two 100ohm resistors.

Aslo which is the positive on the LED? the long end or the short end?

Brian

Brian,

Close. For a 14V supply, with a Vf of 4 V, your resistors would need to be larger to protect the LEDs and give 20mA. The resistors need to be:

R = (14-4)/0.02 = 500ohms

Again assuming that the forward voltage of 4V is rated at a forward current of 20mA.

Yes, the long lead of the LED is typically the one that is connected to the positive supply voltage.

Good Luck!! Hope this helps!! :D

Dave

[Biodragen]

Yes it did.
I went and bought a 6v power supply and some 100 ohm and 220 ohm resistors and played around with it.

I did connect the led directly to the power supply and it lit up, but I don't think it was good.

So I will use two 100 ohm and two led's in series.

Brian

[TNDave]

Brian,

In series it works out to more like 300ohms to get 20mA with 2 LEDS. 2 LEDS = 8V, which is a 6V drop from your 14V supply. To get 20mA you use R=(14-8)/0.020 = 300ohms. 200 ohms gives you 40mA. The LEDs will run at this, very brightly also, but they will not last long before they burn out.

Dave

[Biodragen]

Dave,

I am getting sort of lost with this.
I have a 6v power supply now so the 14v is not being used.
Using the 14v I had a feeling it was a bit much so I just went and baought what I needed.

I am not sure it the resitors I have are going to be correct with a 6v power supply.

What I did notice without the resistors the led heated up.

I would like for these to be at the fullest capacity without burning them out sooner.

Brian

[TNDave]

Brian,

Sorry, I think I am adding to your confusion. You are correct, if you use a 6V supply and a 100ohm resistor for each LED and wire the 6V supply to each resistor, then you are correct. They will get warm, but that is normal. When you said you were wiring them in series I thought you meant you were going to wire the LEDs together.

Here is how I think you are going to wire them (sorry for the rough drawing):

6V supply + ------------------------
R R
| |
L L
| |
6V supply - --------------------------

where the R's are the 100 ohm resistors and L are the LEDs.

When you said in series I thought you meant like this:

6V supply+ ------------------
R
|
L
|
L
|
6V supply - -------------------

Sorry that I got you confused. You are right if you wire it up as my first drawing.

Yes, if you leave the resistors out there is NO current limiting being done and this will burn out the LEDS very quickly.

Hope I haven't made things worse now!
:rolleye1:

Sorry again that I screwed you up. Sounds like you are on the right track now.

What resistors do you have? If you can tell me what you have I can figure out how to wire them up to try and equal 100ohms if you do not have any 100ohm ones.

Dave

[TNDave]

Sorry, forgot to add that 14V would not be too much as long as you have the proper resistors in-line with each LED. My moonlight fixture was built with a 24V supply and 6 LED's. I built it like the second drawing in my above post because I could get more of a dimming range with it.

Dave

[Biodragen]

That's ok .

Yes I mean to have two led's and two resistors with a 6v power supply using 100 ohm resistors.


For my 14v power supply I can make another one with that one.
I would do 6 led's on that power supply.
So you say to use 500ohm resistors for that one.
This is correct then?

Brian

[Sealily]

This was all just so cool that I went to Radio Shack (oomph!) and I bought 6 LED panel-mount holders (ups 0 4029313267 5), 6 LED's, luminous intensity 2600mcd, blue, about 3 bucks each (this was a proto-type, and you always pay too much for the first...), and a nice dimmer switch (knobs to fit were a personal choice extra available to fit your needs and taste) which acted as a resistor and a nice dimmer, called a potentiometer (upc 0 4029311556 2).
All told, even at Radio Shack's prices, it was about $20. Then I drilled some plexi, like we saw here, fitted it all together, and voila, moonight for about 20 dollars, give or take.... I know that we all have broken power supplies hanging around? And the units they used to power? Take it all apart, use the nice connectors (don't throw them out, UN-solder them) and stop spending 20 dollars for the power supplies, when you know those old answering machines are just no good any more...

You guys got me started... I just LOVE this stuff!~!!!

[TNDave]

Brian,

Yes, with your 14V supply and 4V Vf LEDS, you would use 500 ohm resistors to get 20mA and maximum light intensity.

Dave

[Biodragen]

THAAAANNNNKKK YOU DAAAAVE


This is kewl

Brian

[TNDave]

Brian,

Glad it worked out for you. Enjoy!

I find myself sitting in front of my tank for hours when the moonlights are on. The kids are in bed, and before I know it I have been watching the tank for 1.5 hours!!

Dave

[DJ88©]

and before I know it I have been watching the tank for 1.5 hours!!

hee hee


who says we are doing it to recreate some part of nature.. it's all for us. ;) :D

Thanks for helping out Dave. Appreciate it.

[TNDave]

No problem Darren!

Your thread motivated me to build a moonlight of my own, and I think it is my favorite thing about my tank right now!

Now, like you mentioned earlier in the thread, if I could just get motivated to write some PIC code. Although I do enough of that at work I can't seem to get excited about doing it at home!!!

Thanks again for the moonlight motivation!

Dave

[DJ88©]

if I could just get motivated to write some PIC code. Although I do enough of that at work I can't seem to get excited about doing it at home!!!

I know exactly what you mean. Have some started here. all pretty n stuff. But I've just been enjoying the summer off. Haven't felt like doing this stuff till I am back in class in ACK! two weeks.. sigh..

Thanks again for the moonlight motivation

Anytime.. I get bored and I create.... :)









Can you tell I am not bored right now? :D

[madmike]

ok...been following along and built my own, but i could only find a 5k ohm pot at ratshack...what is the difference between the 1k and 5k potentiometer???

thanks for helping the electronically illiterate
Mike

[DJ88©]

The amount of resistance is all.

You are going to want to find one smaller. 5K will be too much. You might get a dim glow. but probably not much.

[madmike]

ok thanks!
Mike:smokin:

[justgettinstarted]

i have a 12V power supply sitting around that i used to run my hood fans on... would this work out ok?

i would just need a stronger resistor than if i was to have used a 6V supply such as you did... right?

hehe... been a long time since i played with any circuts!

[niko5]

justgettingstarted,
I build this same system DJ shows here for 6v and the other day I accidently hooked up 12v and it worked fine... I ran it a few mins with 12v a few times since then but I do not know if there would be any long term damage.

[whodah]

are you planning on a lunar cycle per-night, or the moon varying throughout each night hourly, or both?

i.e. from day1 to day2 i assume there are different intensities, but are you thinking of different intensities at 10pm and 1am as well?

[DJ88©]

Nick,

You'd run higher current through the LED's and shorten the lifespan.

Whodah,

For now I am planning a nightly intensity change. As time goes on and I can find or write the algorithm I will go more accurate.

[justgettinstarted]

so if i wanna run 12V should i use a bigger resistor?

[TNDave]

Originally posted by justgettinstarted
so if i wanna run 12V should i use a bigger resistor?

You need to know the forward voltage (Vf) and forward current (If) of your LEDS. These values are typically Vf=4V and If=20mA. For a 12V supply you would need:

R = (Vsupply - Vf)/If

which works out to 400ohms.

You should size your resistors for whatever power supply you use using the above formula to get the proper current for the proper brightness, while not slowly burning out your LED's.

Hope this helps!

Dave

[justgettinstarted]

Yea it does! thanks!

Now i just need to decide if i want to use blue or red LED's

[traveller7]

Why not use both red and blue?

Red for night viewing and blue for moonlight.
Red with manual switch and blue on a timer.

[justgettinstarted]

i am not that electronically advanced! LOL

[larrylwill]

I've been reading this thread and last night at WallyWorld I found some speaker
lights on sale for $3.00 Their 10" in diameter floresent round tubes about 1/2" in diameter to go on speakers in a car. Their also encased in plastic. The package contained 2 lights and 1 controller, which can be full on or it can be set to pick up music (noise) and flash the lights on/off. All for $3 they also had 2-6x9 ones. They were blue. Looks like about 4 watt floresents. I am
going to use 2 of them in my motor home on the roof. They make a nice light, not too bright about like a full moon.

[Teraphage]

This thread is great...I've learned a ton from it. Way back in high school shop class I remember making night lights where we embedded the LED and wiring in some clear plastic-like substance that we poured into a mold where it hardened. Anyone know what that plastic substance might have been and where to get it. I'd like to make my moonlights encased like that. Thanks.

[freakyreef]

Kinda makes you wish you had payed more attention is science class huh?. :lol:
Great plans and schematics!!

[radecatur]

Hey all,
Group buy on LED's? Im getting ready to buy a bunch at 60 cents a piece.
Any of you guys in?

-Rich

[radecatur]

They are 4000 MCD 3mm blues peaking at 468 nanometers.

[Teraphage]

Using the ideas from this thread I'm planning to build a moonlight/redlight but I'm an beginner as far as circuits go. I'm going to have a bank of 6 red leds on one switch and 6 blue LEDs on another switch allowing me to turn on either or both banks. I was hoping you could comment on whether the attached circuit diagrams will both work, and whether one is better than the other. Any suggestions are appreciated.

[Teraphage]

Actually I just realized the second diagram won't allow me to turn on only red LEDs, but will the first work?

[DJ88©]

First yes. Second no. :)

Nice diagrams. :)

[madman01]

TOOK YR IDEA PUT IN MY TANK IT LOOKS AWSOME

[prof10000]

Ok, I have one point of confusion.

Lets say I have a 12 volt power supply that puts out 9A.
My LED has:
VRev max of 5V
VF, voltage drop of 4V
IF cont. is 20 mA.

Is this correct?

(12-4) / (20/1000) = 400 ohms

So I need a 400 (or greater) resistor.

Do I need to do anything about the 9 amps coming out of my power supply?

Thanks,
Dave

[GreshamH]

No, amps are like reserve power, not a "forced" power so you don't need to worry about to many, just not enough of them.

[prof10000]

Just wanted to double check before I blew anything up.

Thanks,
Dave

[StephenA]

Thanks for the schematic, I added a photo cell to mine to turn it on when the other lights go out.

[Rebels23]

Nice Job!!!

[thereefgeek]

good idea using the photocell!

[JCorbett]

I just purchased the 60 degree superbright leds. The 30degree leds I originally put together were to narrow of beams over my 180 for my liking.

[JCorbett]

I am hoping to plug my unit into my Solar1000 lunar port to control the cycles. Solar1000 directions indicate the port is for incandescent only. Should I be able to do so? or do I have to make a modification for Solar1000 to run my diy leds?

[StephenA]

Where did you purchase the 60 Deg LED's? The Solar1000 should work on anything other than Flouresents.

[Coral Dilema]

Hey guys, I need to hear from some people that have access to cheap electronic components, I have a good design going on a moonlight that will emmulate the lunar cycle, both phase and rise/set time. My only problem is I have been out of doing home projects for so long that I dont have any good contacts for parts anymore. And I dont need to purchase 1000 of a single item in order to get a discount.

Items im looking for specifically: 12 bit DAC (not ADC, need a simple version of this, not one with serial input). Also looking for some precision timebase chips . . LM555 isnt going to cut it for this. Thats about it, the rest is made up of a triangle wave generator, an op-amp, and an optocoupler. Fairly simple design and im sure it will work, I just cant find a good source for parts, especially the DAC. Doesnt have to be 12 bits, 8 would work, 10 would be ok . .16 is way too many but still doable.

Thanks guys, Please PM me if you can help out, I have so much going on I dont get a chance to check my threads too often.

[JCorbett]

I really need to learn how to add links. I bought them at
www.lcled.com. They sell sample packs of 15 for about $20.

[chetscc]

^

[BeanAnimal]

I got some decent DACs from Newark....

DAC0832lcn Jameco also had them a while back.

In another thread (the radio shack led thread) and a few threads a while back, I explained my design for a Visual Basic controlled aqurium. Moon lighting was one of the features.

I am very interested in your design, if you are will to share it. I would however most likely use software to control the phases instead of a timer.

Bill

[Scuba_Dave]

Great thread, now I'm going thru all my "junk" to see what spare powerpacs I have. I have a 3.6v one, but that may be too low, requires 15 ohm resistors then...?

[StephenA]

I would think 3.6 would be too low. The min I have used was 4.5 and it used a 47 Ohm.

[szwab]

I have an aquacontroller it has a built in lunar program that varies intensity and timing. Could this be used with that or no since it works through a transformer? Any help would be great.

thanks!

[StephenA]

No, since it works thru a transformer. You'd have to find a way to output DC voltage at around 2 to 5 volts for it to work.

[Racer1]

Has anyone considered using the new Ultraviolet spectrum LED's instead of white's to show the irredescence of some corals? (it is like a black light) I plan to, as I have a standalone one that is barttery powered. It works with some freshwater fish as well (i.e. glo-fish). I just thought I would throw that in there.

[niko5]

I thought about that.. IV got some UV LED's let us know how it works.

[Racer1]

Would you be interested in a trade or something on the LED's? I have about 25 years of Electronics experience to pull from. What spectrum are they?

[badpacket]

Quick Q: While a bit more advanced, isn't there a somewhat simple way to hook up a 555 or R-C circuit to strobe the LED's. I believe I remeber power savings of something like 60-70% of you strobed the LED's at 60 hz.

Whoopa, found it.

http://66.102.7.104/search?q=cache:9_aJQeY7h0IJ:www.maxim-ic.com/appnotes.cfm/appnote_number/1865/ln/en+led+555+save+power&hl=en&ie=UTF-8

[ScottT]

Great Thread. I've got my LEDs and was calculating my resistor needs when I asked myself the following question:

Why do you need one resistor per LED? If you can put a POT on one side of the transformer and use it as a dimmer, why couldn't you simply put a single resistor there rather than one for each LED? I realize you wouldn't have the dimmer capability, but I'm just throwing that out because you'll know where in the schematic I'm talking about...

As long as the resistor causes the appropriate voltage drop, you could then wire all the LEDs in parallel AFTER the resistor and it would eliminate the need for one resistor/LED....

Where is my thinking wrong?

thx for the great thread!

P.S. I'm still planning to use a POT for dimmer purposes, but if I find one that provides 0 resistance when turned all the way to one side, I could just put my calculated resister in series with it and that would ensure I never drop below my minimum resistance needed to ensure I don't push too much voltage across the LEDs.

[Teraphage]

As far as my understanding goes, you can definately do this, with 1 resistor for all your LEDs wired in series. But if 1 LED dies, your circuit is gone and none of the LEDs will work. At least with everything wired in parallel, one blown LED doesn't shut the hole light down. Also, I'm fairly sure resistors can fail, which means all your LEDs could fry with them wired in series. If you have a resistor wired with each light and one fails, you'll just lose that one.

Steve

[ScottT]

That pretty much makes since. I'd wire mine in parallel after the single resistor which would keep me from losing all LEDs if one goes out, but I'd still be vunerable if my single resistor fails.

My setup will be a 4.35VDC with an LED that takes 3.3V @ .02A, which leaves me needing a 52.5 ohm resistor for full insensity.

I'm only running 2-3 LEDs (20mA ea) on a 400mA source, and the power requirement is only like .02W, so a .25W resistor wouldn't be stressed... would this reduce the likelyhood of the resistor failing?

I guess the bottomline is that the resistors are cheap and I'll have more things to solder ( :) play with :) ) if I use multiple resistors!

[tpeterson70]

About the single resistor for whole circuit, great idea.
Tera, if the resistor fails it will not fry all the LEDs they will just go out until you replace the resistor. Resistors always fail open and ussually they fail because another more active componant attached to them failed.

Also I see everyone talking about beam angle of the LED's, I'm using cheap ($2.00 each @ Skycraft in Orlando area) bright blue LEDs and I aim them up at the reflector. On my 55 FOWLR I have two LEDs that cast a nice soft blue tone over the entire tank with no spotlight effect. My 46G Bowfront only needs one LED. I haven't finished the 125G reef yet as I'm looking into the "Black Light" LEDs.

Another question, I saw in this thread people were thinking of pulsing the LEDs to save energy. Why? 10 LEDs would pull about the same amount of juice from the wall as one 90 elbow in your plumbing. The heat given off by the xformer is more than the energy used by the LEDs themselves.

[smurf04]

tagging

[Teraphage]

Originally posted by tpeterson70
Resistors always fail open and ussually they fail because another more active componant attached to them failed.

Thanks for the info and the correction:)