LED wiring help?

[gololf]

I have made a Nano tank 2 gal out of a gum ball machine.

 

I called around to different LED manufacturers and got one to send me some white ones they made that are rated 4000 to 8000 mcd on 2 different models. They sent me 6 of the 2 to 4K mcd LED's and 6 of the 4 to 8K mcd LED's.

 

I want to wire them up around the top of my bubble gum ball tank as shown in the pics here: http://www.nano-reef.com/forums/showthread...?threadid=21975

 

Was going to create a shield out of a curved piece of PVE vut down the middle in a half shell and wire them alternately to point inwards (they have a 30 degree lite spread).

 

Can someone give me an idea of the DC power source and can i use the 100 Ohm resistors I have on hand. I have a 4.5 volt converter...300 mcAmps...will that be enough?

 

You can see the 2 blue LED's I piped down thru the air lift tube to the bottom compartment.....gonna make one for moon light and make the daylight one shine in form around the top.

 

Thanks

FL Bob

[onthefly]

Can't do it without one more variable.....what's the max amps the LED's will take?

 

Basically, use the formula "resistance=volt/amps"

 

make sure everything is in the same units (i.e. milliamps, millivolts, etc).

[gololf]

Will do the lookup...and work the formula....let ya know

 

 

FL Bob

[zzpw3x]

It depends on the forward voltage of the LED (Vf). Most of the high intensity LEDs are around 3.4v at 20mA. So if you have a 4.5v source, R = (4.5-3.4)/20mA = 55 Ohms. If you really want to use the 100 ohm resistors you have, palce 2 in parallel to get 50 ohms, which is close enough.

 

You will obviously need mulitple LED's, so just place the LED/resistor setups in parallel. With a 300mA suplpy, you use up to 15 LEDs. My guess is you will need every one of them to get enough of light.

[gololf]

I'll try the pair (in parallel) with the one 100 Ohm resistor and put the 12 that I have in a string. Suppost to get 2800 to 8300 mcd range from them according to the manufacturer....we will see.

 

Maybe I can find a lightmeter in one of my boxes of camera supplies that will give me some data.

 

 

FL Bob

[zzpw3x]

Don't put the LED's in a string, they must all be parallel also. For each LED, you will need 2 parallel resistors. You will then end up with 12 LED/Resistor strings and each one will be connected to the 4.5v power supply.

 

If you need more help I can draw up a quick schematic.

 

-Dale

[gololf]

Just tried a couple of wiring jobs

 

Did 2 LED's parallel to one 100Ohm resistor...hooked up to a 3v 200ma dc converter it was not that bright...so I took off the resistor and put the power to it...twice as bright.

 

The DC power supply was an old one...so might not have been up to par as it was.

 

Maybe I don't need resistors at all...if I hook them up parallel (all 12) and use a 6v dc supply...300 ma

 

 

Let me know what you think

 

The white LED's are # L513WC-15DS

and # L513LWC-15D

 

I also have some blues for my moon string Agilent Tech

# HLMP-CB30-M0000

those for cars?

 

Thanks,

FL Bob

[zzpw3x]

I would still use the resistors. If you had 1 resistor and 2 parallel LED's, I wouldn't expect them to be bright.

 

Not using the resistors will shorten the life of the LED. The typical lifespan is 10 years, so you may never really notice it even if it gets cut in half.

[gololf]

So I should have one resistor for each LED?

 

And what is the number of LED's in a string I can have (at best efficeincy).

 

12 LED's for instance......6 volts with one 100 Ohm

(or a different resistor?)

 

Could you maybe draw me a diagram or discribe it to me?

 

 

Thanks,

 

FL Bob

[zzpw3x]

See the attached image. The resistors can be 100 ohm up to 130 ohm.

[gololf]

I really appreciate the help...I will put this together and slap up a pic of it.

 

 

thanks again!

 

Fl Bob

[bravoreefer]

Not using a resistor will cook a LED in about 5 seconds, I learned the hard way...