We have got a 20W led ,RGB from a good seller in China.

I have a few questions regarding the led (see the attached image)

  1. Is there a data sheet to this Leds? something generic ?
  2. How can you know where are the RGB pins, and the voltage pins ?
  3. I tried to understand how are the control lines are working, and i was thinking that like any other led strip the control lines are only connects the RGB lines to ground, with a high current N-CHANNEL FET .

The seller told me this :

R:14-17V       G:21-24V         B:21-24V
 R:1150mA-1400mA   G:800-950mA  B:800-950mA 

Is it means that the control lines are with these voltages ??

Please see the attached image. thanks very much.enter image description here

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    \$\begingroup\$ (1) and (2) - Ask the "good seller". He will respond if he is good. \$\endgroup\$
    – Eugene Sh.
    Jul 9, 2015 at 16:37
  • \$\begingroup\$ Have you bodered to read my question? Cynics is not good for your health. The seller did provide answer which seems not reasonable to me and since leds are usually the same for each package ,i am asking here the good people for help. \$\endgroup\$
    – Curnelious
    Jul 9, 2015 at 16:40
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    \$\begingroup\$ @Curnelious your question doesn't say "I asked the seller didn't reply" \$\endgroup\$
    – ozg
    Jul 9, 2015 at 16:46
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    \$\begingroup\$ These are probably just naked LEDs in series. You could find the pins by trial and error with a lab power supply (voltage somewhat higher than the ones specified and a low current limit of a few mA should do). Note you also need quite a bit of cooling to run it at full power. \$\endgroup\$
    – starblue
    Jul 9, 2015 at 16:52
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    \$\begingroup\$ "seller did provide answer which seems not reasonable to me" OK, just to help us out, what (exactly, not YOUR version of it) did the seller say, and why doesn't that help? \$\endgroup\$ Jul 9, 2015 at 18:13

1 Answer 1


Just poke around with a 30V power supply with a 1K resistor in series, as Starblue suggests and you'll quickly figure it out (I suggest the resistor because the output capacitor of even a current-limited power supply could damage the LEDs conceivably)

Probably 3 strings of series or series/parallel with a common. Whether it's common anode or cathode is unknown.

Chances are the top strip in your photo is the common, and the bottom left is red and the other two are green and blue (maybe not that order for green and blue).


simulate this circuit – Schematic created using CircuitLab

You need to limit the operating current into the LEDs to less than the smaller of the rated current and the maximum allowed by the power dissipation. As in the comments if you power this up at anywhere near the claimed 20W input power it will see perhaps 18W of heating and will expire in short order.


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