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Which diagram would work best(want leds to work at their max potential, Help? Answered

specs on all 3 leds 

1 watt, red green blue
Maximum forward voltage: 4 Vdc
Maximum forward current: 350/ 700 mA

(if you pick a diagram with a resistor please let me know what rating Ty)


Hi man,

Do you have these or are you thinking about buying them?
Saying what you want to do with 'em will help people give you better answers.


I'm sorry, i want to be able to plug the 3.5 jack into an audio source, and have them flash to the music.

OK, you'll be looking at something like this then?
(In that there's a left-right split.)

The LED you point to (Cree XLamp(TM) 7090WRD. Extremely high-brightness white LED) needs a constant current driver as frollard mentioned, and a non-battery power supply, as others suggest.

Best wishes for your build.



Best Answer 7 years ago

There is absolutely no way 2 9 volt batteries can a) spit out 3 watts, b) last for ANY duration.

http://www.dealextreme.com/details.dx/sku.13555 3 bucks, 12-16v input 3x1w driver.

A constant current driver would be a smart move -- this one powers 3x1watt leds in series, just supply 12-16 volts. I would recommend series protected lithium batteries (3.7-4.2 volts each) -- you can get them in the form factor of AA batteries, or otherwise, with a charger for about 10 bucks (what you'd spend on a pile of 9-volts). The smart driver needs no series resistor, and wastes a lot less power. Remember to heat-sink those bad-boys! They WILL get hot and burn out.

i was looking for heat sinks, any idea where to pick these up?

Anything made of metal, probably aluminum, so long as it doesn't sort out your project.

One problem, to get 18 volts from 2 nine volts you must put them in series which is bad for nine volts due to the fact they can't deal with that much current. You have then in parallel.

For heat sinks take some off an old video card or mother board or search ebay for laptop heat pipe and you can find some nice heat pipes that can cool up to 10 watt leds

make sure to use one of the pareral curkets & not a series one because in a series the power is divided between the number of led's. A pareral uses more power between each led so it will give better results.
also if you are looking at two batterys wire them as a series so they work as one and run out in the same time. (like below\/)

delete later.jpg

7 years ago

Judging somewhat by the colours you used, I assume you found this circuit on the 'net?


They're using a 12V battery without a resistor, since the sum of the diode voltage drops will be slightly greater than 12V.

In your case, scrap the 9V batteries. They can output 600mAh max, but not if you try to draw 350mA (and especially not if you draw 700mA!) That means your battery life would be 1 hour or less. 9V batteries are too expensive to be worth it.

Instead, use AA batteries, ideally rechargeable ones. You could probably use 8 rechargeable AAs in series with no resistor using circuit #4. Or, 7 non-rechargeable AAs with no resistor. But to know for sure I need the exact specs of these LEDs.

yes thats pretty much the diagram i used. i kinda figured that my power source was way to low, i was interested in a wall power source

A wall adapter between 9 and 12v, with a current of at least 400mA would work. With a voltage above 10.5V you'll need a resistor.

i have a wall adapter
heres the specs:
class 2 transformer
input 120v @ 60hz
power in: 13.2 w
Vout DC: 12

That'll work fine. Assuming 350mA devices, and adding in a safety margin, you'll need a 4.7 ohm, 1 watt resistor. Attach according to diagram 2.

Those batteries aremn't in series to give 18V, and are you really using 9V duracells ?


A laptop supply would be ideal. Running in series is a better idea than parallel.

If you want eighteen volts You need to wire the postitive to the negative, And becuase the 1 watt LED's are only 6V you dont need that much unless you wire the LEDs in series.

I would stick to wiring the LEDS in parrelel and running them from a 6V source, such as a wall transformer or One of those big 6v batterys (i would recomend a The wall mounted transformers as the can give a constant charge and can put out about 11w). 9v batterys wont last long. If you really want to use 9V batterys I would but a 320 ohm resistor (if wriring in parralel, but I Dont recomend using a 9V battery.

I have made this circuit and used a 12v 1.5ah battery with a 12v LED spotlight



A wall transformers just like a phone charger , a wall adaptor in other words, from reading you other comments it seems that you have a 12 v wall adaptor. I would either wire the three LEDs in series , or wire them in parrelel with a 320 ohm resistor.


link to the led's i have