DIY moonlight with LED... anyone? - Page 8

schemo · #**176** 11/20/2002, 09:13 AM

i would just like to say this thread is awesome!!!!! i've read this thread over and over and i understand it now but the only the only thing i don't understand is how to wire up a resistor in parrallel or series?? i understand everything else but this is the thing that get's me.

i know that if you run two 100ohm resistors in parrallel you drop the resistance to 50ohms. just as if you run two 100ohm resistors in series you increase the resistance to 200ohms, right???

the thing that gets me is how to wire the resistors in parallel or series running to the LED's???

Can someone please explain this to me somehow?? maybe possibly with a drawing???

thanks
schemo

Dipal · #**177** 11/20/2002, 09:23 AM

schemo:

you are right about the calculations on the resistor in series and parallel. To wire up the LED and resistor, you do it in series as shown in this diagram. The --/\/\/\/-- is the resitstor, and this -|>- is the LED

Positive --------/\/\/\/---------|>--------------Negative

wam · #**178** 11/20/2002, 09:31 AM

Dipal:

example
Ohms law = Power supply / led ma = ohms
12 v /.02 ma = 600 ohms resistor needed

led calculator = (Power supply - forward voltage drop)/ led ma
(12v - 4 v)/.02 = 400 ohms resistor needed

Now which one should we use?

Did you do anytest on this? Just curious?

Dipal · #**179** 11/20/2002, 09:35 AM

wam, a freind of mine has my meter and i tried to get it last night from him but had no luck. I will see if I can drum up something here at work. sorry about that.

Dipal · #**180** 11/20/2002, 10:03 AM

WAM, just did a bit of testing. I took a red LED, don't know the specs on it and a 675 ohm resistor with a 12 volt ps and here is what i found out. If you take ohms law to this you would have 12/675 and get 17.7 mA. But when I hooked up the circuit and took a reading, I saw 14.61 mA. So when you go back to Ohms law and calculate for voltage you get 0.0146 * 675 you get 9.855. So 12 - 9.855 = 2.145. Like i said i don't know the forward voltage drop on the LED we used but 2.1 sound right. So my inital calculations are wrong, and yes you do need to subtact the forward voltage of the LED from the Supply voltage prior to calculating the resistor.

FatherDougal · #**181** 11/20/2002, 10:38 AM

For all those who are getting confused by the circuitry, resistors etc., I highly recommend the site below which has very nice clear circuit diagrams and explanations. It's what I used to make my setup (see pic somewhere back in this thread)...

http://www.otherpower.com/otherpower_lighting_leds.html

wam · #**182** 11/20/2002, 10:52 AM

I wired up a blue led 3900 mcd 20 ma 4v forward voltage to my 13.8 2.5 amp power supply last night. I use a 680 ohm resistor.

It worked and was still bright. So, my conclusion is that if I used the led calcualtion vs. the ohms calculaiton would be 490 ohms vs 690 ohms. I would not see very much difference.

The only thing I did not like about my leds are the brigthness. They are a 3900 mcd. I was looking for some really deep dark blue colors. my color rating is around the 470 mark.

Any recomendations where to get the real dark blue color? Radio shack?

schemo · #**183** 11/20/2002, 12:36 PM

Dipal,
ok i understand how to wire them up in series but how would you let's say wire two 100ohm resistors in parallel to make 50ohms then wiring it to the led? this is what confuses me. would it be something like this????

|........|
/\/\/\/\/----100ohm
|........|
/\/\/\/\/----100ohm
|........|
|........|
---0--- ---LED

/\/\/\/=resistor
---0---=LED
.........=nothing

diagram to wire two 100ohms in parallel to drop to 50ohms???

would this be correct?

thanks
schemo

Dipal · #**184** 11/20/2002, 01:30 PM

schemo.... that is not right here is what you need to do.

............|---/\/\/\/---|
.+.------|................|------|>------- -
............|---/\/\/\/---|

you see in this diagram the two resistors are wired in parallel each are 100ohms which will give you 50ohms. the formula for that is 1/((1/R1) + (1/R2)) or the inverse of the sums of the inverse of each resistor. 1/((1/100)+(1/100)) = 1/((0.01+0.01)) = 1/0.02 = 50. And then you add in your LED in series with the resistors that are in parallel with each other.

note --|>-- is the LED

DL · #**185** 11/20/2002, 02:05 PM

I've read these posts too much. Totally confusing to us electrically challenged.

The easiest I've come up with is the following diagram:
http://archive.reefcentral.com/vbull...&postid=855280

My question is, can I copy this and use less 10.5 (3 LED) strings and still use 68ohm resistors?

So could I use 3 or 4 strings of 3 LEDS and use the 68 resistors?

Is this right using this math?:

12v - 10.5v = 1.5v 1.5/.02 = 75 therefore 68 would slightly overdrive them?

schemo · #**186** 11/21/2002, 11:21 AM

Dipal,
ok i got it now after i posted my diagram i kinda figured it out, with alot of thinking

, thanks though for responding.

schemo

wam · #**187** 11/21/2002, 01:51 PM

I noticed several people have used the Radio Shack project box to house there leds..great idea.

Does anyone know where I can get a small bus bar to fit inside this?

"I used one of the project boxes from Radio Shack as did devin, except I included a bus bar on the inside of mine so all i had to do was attach the positive and negative to each side of the bus bar and then attach the LED. "

barebottoms · #**188** 11/21/2002, 01:53 PM

Breadboards, Proto Boards, Etch your own board, order the tracks from the links I've provided.. ....

Dipal · #**189** 11/21/2002, 01:53 PM

Wam: Try checking out www.mouser.com or www.digikey.com

Looper121 · #**190** 11/21/2002, 03:32 PM

Just got mine wired up, and now my clown swims in the beam all night!! Really cool effect. Do you think it will keep the clown form "sleeping?"

musicsmaker · #**191** 11/27/2002, 12:36 AM

WOW!

I didn't even realize this thread was still going. I noticed that a few of you were trying to get one that was good and bright. http://www.hosfelt.com/ has ones that are rated at 6000 mcd, 466nm, and 29.5* viewing angle. Just thought I would share because I've checked with most of the links in this thread and hosfelt had the brightest ones, and the viewing angel is kept wide. Kind of pricey though. $3.99 each.

nwappleby · #**192** 01/17/2003, 10:53 AM

can I use this in an 46g bow, and it still be bright?

traveler911 · #**193** 02/13/2003, 10:50 AM

Great thread.
Thought it deserved a bump

wam · #**194** 02/27/2003, 04:16 PM

I noticed the miracle beam Hi-Lite System comes with the power supply, adapter box with ports for 5 modules. I was wondering if anyone has used their own blue led's and hooked them directly to the adapter box. If so, could you tell me how you did it.

Did you attach a plug (jack?) like thier led modules have and plug it right into the adapter box. I was wondering if that would work with out adding a resistor?
I have read through all the posts on the subject of led's and could not find anyone that used the hi-lite system with thier own led's.

McSierra · #**195** 03/27/2003, 03:23 PM

Quote:

Originally posted by FatherDougal

First let me start with: Nice Tank..!

My question for you is what size is your tank?

I like the Amount to light that you have in it.. How far apart are the LED's? For my final question: How high off the water level are the LED's Mounted..?

TIA,
Andre

FatherDougal · #**196** 03/27/2003, 03:55 PM

So the old LED thread has come back to life again!

To answer your questions the tank is a 46 gallon bow-front. The six LEDs are each about 3 to 4 inches apart and are mounted inside the hood, around 2 inches above the surface of the water.

To anyone that's reading this thread thinking about doing their own DIY LED nightlighting I say - go for it! If I can do it with my non-existent DIY skills and electrical knowledge anyone can!

Here's a recent night shot of some of my zoos...

bachtor · #**197** 03/31/2003, 12:44 PM

Father Dougal--

Came across this thread also. Was originally looking for a red led flashlight, but this seems much better. Since I also have a 46, what type of LED did you use (brightness)? I see you used 6 of them.

electric130 · #**198** 04/01/2003, 07:31 AM

Quote:

Originally posted by bachtor
Father Dougal--

Came across this thread also. Was originally looking for a red led flashlight, but this seems much better. Since I also have a 46, what type of LED did you use (brightness)? I see you used 6 of them.

red flashlight and blue moonlights are for two completely different uses.

bachtor · #**199** 04/01/2003, 12:05 PM

thanks, I should have been more clearer. I originally intended to purchase a red LED flashlight, but came across the concept of using blue LEDS as moonlight simulation, as well as red LEDS for night viewing. I wasn't aware that these type of projects were an easy DIY until I came across this thread. Why not have both? I like this idea better, therefore, I won't need a red flashlight.

I plan to use Radio Shack red LED's (super bright, 5000MCD), but was wondering from father dougal what type of blue LED's he used, since he has the same size tank, and also made a previously mentioned the ones he bought were too bright.

Hope this helps.

FatherDougal · #**200** 04/01/2003, 02:00 PM

bachtor - my setup is more for aesthetic effect than for night-viewing or moonlight simulation. I don't really know how it would look with red LEDs but if that's the look you want... Maybe you should get night vision goggles instead - I hear the Syrians are doing a good deal at the moment.

The LEDs I used were 3 x 1.3cd 30deg lights and 3 x 3cd 15deg narrow focus lights. Although I said at first they seemed too bright I'm pretty happy with the light level now.

Also, if you get a DC convertor plug with a built-in voltage selector switch as I did you'll be able to choose and adjust the light level as you like.