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Old Oct 03, 2013, 10:42 AM
Rsetiegerd Uesr
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Hobby King high density LED bars

I got some of the LED bars they sell just to check them out. I may put them on a quad I'm building, I don't know. HOWEVER, most of the strips are not useable without some modification that I'm going to need some help on.

Link.

I got the green one out of the package first, hooked it up to 12v and WOW HOLY COW it's like looking at a light saber. Or even a welding arc. And the thing gets incredibly hot fast.

So I put it on my watt meter. The light bar rated at 3w is consuming THIRTY FOUR watts. So the specs are off by an order of magnitude. Not too bad for Hobby King.

I also got some white 3w bars. They consume 13 watts and get less hot.

I also got some red 3w bars. They are rated for 2s OR 3s and come with a little voltage regulator thing on them. They consume 2.7 watts and barely get hot at all. They aren't as bright as the sun, but they are plenty bright.

I would like all of the lights to work like the red ones do. I unsoldered the red bar from the voltage regulator, then connected it to the green bar. The green ones lit up, but they were extremely dim.

So, electronics GURUs, what should I do? Try lower voltage? Use a resistor? I really would like to be able to run these from 3s lipo. I'm not an electronics whiz, but I know the basics, I have a multi meter and a camera. If you need more info let me know and I'll get it.

-J
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Old Oct 03, 2013, 07:36 PM
Rsetiegerd Uesr
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USA, AR, Cave Springs
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I did some further testing this afternoon.

I hooked my CCBEC pro up to my watt meter then to the LED bars.

<7v nothing happens.
7v the LEDs light but extremely dim.
9v they are bright. The white consumes 1.7 watts and the green consumes .8 watts.
9.5v the green and white both consume 2.7 watts.
10v the green and white both consume 3.9 watts.

So what is the cheapest way I can make my 3s lipo work with the LEDs that require 9.5v? Resistors would waste power right? I'm not even sure how that works with LEDs. Unfortunately the regular CCBEC only goes to 9v flat. It takes the PRO to go up higher and that is much larger.

Any help is great.

-J
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Old Oct 04, 2013, 06:27 AM
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The only option I see here is to add resistors. One problem is that you cannot run less than 7v.

One thing I noticed are the extra solder pads at the opposite end of the light bar? You could try soldering them together starting with red, to see if that reduces current to green and white?

A resistor takes your extra current and turns it into heat. As you've already figured out, different color LEDs require different amounts of current. Use your red LEDs as the standard for brightness, and match your other colors with different value resistors.

I'd like to see if someone knew of an alternative and would like to know for future personal reference!
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Old Oct 04, 2013, 08:34 AM
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Grab a variable resistor iin the approximate range you need, then you can dial the brightness to where you want it, then measure the pot and get resistors closest to that value.
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Old Oct 04, 2013, 09:55 AM
Rsetiegerd Uesr
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I did measure the voltage regulator that is attached to the red ones, it puts out just under 5v. So that's not going to be compatible at all.

Would it be more efficient to use one of these instead of resistors, in terms of wasted energy? Or will the regulator waste just as much as the resistor would?

-J
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Old Oct 04, 2013, 02:23 PM
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What about using a diode to drop the voltage? I used a few N3001 diodes to drop the voltage of the 3s lipo so that I could use it in an older tx. I'm not sure what kind of current they can take though.
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Old Oct 04, 2013, 10:34 PM
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I think that regulator will suck just as much, if not more power. Why can't you start with the green and white, then the red? It's totally possible for them all to work, you've just got to use more power than is preferable.

Most High intensity LEDs can run from only 3volts. Seems like they've added some major resistance to make them run at a 7v minimum.
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Old Oct 04, 2013, 11:10 PM
Rsetiegerd Uesr
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I stuck them on my quad. In this picture they're running on 2s lipo. The white is not nearly as bright as the red. The red is consuming 2.7 watts per bar, while the white is only consuming .8 watts per bar.

I bought a couple POTs today and figured out that the whites and greens need about a 6-8 ohm resistor in series while hooked to a 3s lipo. So I'm going to buy some regular resistors and see what I can do.

Thanks for the help on that one!

-J
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Old Oct 04, 2013, 11:14 PM
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Either way, that looks great dude! Post more pics when you finish!
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Old Oct 30, 2013, 05:48 AM
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Well this just figures hobbykong stocks cob (chips on board) leds. I just ordered a few of these from dealextreme (extreme wait time for shipping mostly) and they took 24 days to arrive. Not even hobbykong is that slow.

Anyhow I can confirm the need for a good size resistor on these things. 3s is too much power. I measured my slightly larger blue cob lamp at almost 150 degrees fahrenheit and one chip is already blown out.

This should be helpful if you are too lazy to learn led resistor math like me:

http://led.linear1.org/1led.wiz

I'm not sure about alternatives to using resistors. Can anyone confirm whether a brushed esc could be used as a dimmer like some have done for their led strips?

Also one or both of these might fit the bill:

http://www.dimensionengineering.com/.../anyvolt-micro

http://www.dimensionengineering.com/products/anyvolt3

Now I'm going to power on the lights on my heli. Do not look directly at it.
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Old Oct 30, 2013, 07:26 AM
Rsetiegerd Uesr
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I have several of these installed now. Two pairs of white on the front of two quads, and one pair of green on the back of one and one pair of red on the back of the other.

The Red have a board with them and can be powered directly from 3s lipo. I checked the voltage coming out of the board is like 4.5v there about.

The Green I ended up putting a 10ohm resistor in series with it. This lowers the voltage and it looks great.

The White I actually had some of these laying around that need about 3volts. Since the White bars work great on 9.5v and the other lights need 3v and a full lipo is 12.6v... I hooked them up in series. It works great.

I wish HK would just explain all this better on their page. The lights are awesome and well worth the extra effort to get them to work correctly.

-J
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