1
\$\begingroup\$

Will a 12-24 Vdc, 2 Amp Max, 5-Pin Strip Light Controller, with IR Remote, the ones commonly available for multicolored strip lights via Ebay, work to control (5) CREE XM-L RGBW 10 Watt LED Emitters connected in Series? If not, please advise why not. And, if there is another way to wire up the CREE LEDs and still use the strip light controller, perhaps in parrallel, then please advise how to do that. I like the small footprint of the strip light controller, which has terminals for all of the colors available, and provides 12-24 Vdc. But, I have heard that strip lights are wired in series sections and joined in parallel at each segment of 3-6 leds in order to form the complete 300 led strip. I don't want to blow the CREE LED Emitters if I wire them up in series, and apply the strip light controller to the circuit...but, it would be nice if I could make it work somehow due to the small footprint of the strip light controller, versus having to install Meanwell brand controllers for each of the respective colors.

Strip Lights with Controller/Remote

CREE XM-L RGBW LED Emitter, 3.1Vdc Each, Max Current = 1 Amp each

\$\endgroup\$
1
\$\begingroup\$

I think that, yes, you can use that controller for your LEDs. Note that each Cree LED has 8 terminals. You will need to wire each of the Cree stars in series with the one next to it, giving you 4 series strings with 5 LEDs in each string. This will give you a voltage drop somewhere near 16V for each of the colors, possibly excepting Red. Some Red LEDs run with 1.7 - 2.1V drop, some run with a 3.2V drop similar to Green, Blue, White. You will have to measure to find out for sure.

Do note that you need to provide current limit for each of your strings. The distributed LED strip that you show in your picture has series resistors for each group of LEDs. You can use active current limit or simple resistors. The advantage of the active current limiters is that the current remains the same even if the voltage varies, so long as the voltage remains above the dropout voltage of the current limit plus the forward voltage of the LED string.

Resistors are simpler and cheaper but the current varies as the supply voltage changes. Note that if your supply voltage is fairly close to the voltage drop in the LED string, small changes in supply voltage will result in large changes in LED current.

Regardless of which current limit technique you use, realize that it's going to get hot. Assuming 1 Amp forward current per string running from a 24V supply rail, each current limit stage is going to be dropping about 8V at 1 Amp, which is about 8 watts.

\$\endgroup\$
  • \$\begingroup\$ Hello Dwayne, thank you for your response. Yes, I agree that I could duplicate the strip light circuit using the emitters, using current limiters, and I also agree that current limiters would be the wisest way to go because of the fluctuations you mentioned. But, I'm not sure which currently limiter values or resistor values to incorporate into the circuit. I would have to have an actual sketch, with values for resistors and current limiters, or I'm afraid I'd probably blow the circuit out. :-) \$\endgroup\$ – Quizcat Jan 20 '15 at 1:24
  • \$\begingroup\$ I know just enough to be dangerous, and would have to be lead by the hand to pull it off...but, thanks for confirming what I was thinking as well, that it could be done. But, I would have to embellish the circuit to protect the emitters. Thanks again! \$\endgroup\$ – Quizcat Jan 20 '15 at 1:28
0
\$\begingroup\$

No, not as is. Those controllers work by passing through the voltage as a common anode, and typically have n-channel mosfets controlling the low side of each color channel. There is no current limiting in them. The led strips they work with typically have 3 diodes plus a resistor in series (or 6 diodes for the 24v versions) per segment, and multiple of those segments in parallel. The resistors provide the current limiting, and it's you that has to limit the size of the strip to 2 Amps.

The cree 10W diodes are similar, but are high amperage compared to the 0.06W leds in the led strips. Depending on the Cree led, it probably takes around 3 amps between the three (four?) Colors, and have no in built current control. You must use a current controlled regulator source, as using resistors for these high amperage is impractical at best.

\$\endgroup\$
  • \$\begingroup\$ The LED Strip I have claims to be putting out 72 Watts for a string of 300 LEDs (approximately 16.5'). When you mention that LED strip LEDs put out only .06 Watts, is that just a generalization, not knowing what kind of strip I have, or should I assume that the entire strip that I have, which claims an output of 72 Watts, is actually only putting out 18 Watts (.06 x 300 LEDs = 18 Watts)? Thanks very much for your detailed explanation above. Very much appreciated! \$\endgroup\$ – Quizcat Jan 19 '15 at 20:43
  • \$\begingroup\$ Each diode uses 0.02A at ~3.3v, but in series of 3, use 0.02A at 12v 0.24W ( with the resistor). Each segment has 3 colors, so 0.72W. Times 100 segments in 5M, 72W, not adjusting for voltage droop in the 5M of fpc the strip uses \$\endgroup\$ – Passerby Jan 19 '15 at 21:15
  • \$\begingroup\$ The reason I asked about the wattage, is that I am considering using one of the strips, 192" of one, 8 strips cut to 24" lengths, for an aquarium light. So, I am trying to calculate the amount of light in watts that might be delivered to the plants in a 20 gallon tank. So, just to clarify, is it producing 72 Watts of Light, more or less with a slight drop over the full length of the strip, or is that the total Wattage being consumed by the circuit, and in reality significantly less light is being produced in watts? \$\endgroup\$ – Quizcat Jan 19 '15 at 22:16
  • \$\begingroup\$ I realize that I should be measuring light in "PUR" to know what amount of actual light is actually reaching the bottom of the tank, but I don't have the equipment to do that, and must rely upon watts per gallon to estimate the amount of light in watts that the strip will deliver. I need to achieve at least 3 watts of light per gallon to benefit the plants (ie: at least 60 watts to a 20 gallon tank). \$\endgroup\$ – Quizcat Jan 19 '15 at 22:17
  • \$\begingroup\$ About 20% of the blue and green is wasted in the resistors as heat, more like 45% for the red, per segment. Considering all on for white, your looking at probably 60W being converted into light, ball park number. The off the shelf led strip is more efficient than a comparable incandescent or so they say, but not exactly efficient in design. \$\endgroup\$ – Passerby Jan 19 '15 at 22:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.