I've just bought 5 meters long 12V analog RGB LED strip and I'd like to turn it on! There're 60 LEDs per meter so, totally 300 LEDs and each LED consumes 20mA.

Here're my questions.

  1. From internet guide like this(https://learn.adafruit.com/rgb-led-strips/usage), power is directly connected to white line then where is ground? (single LED have 4 legs - Red, Green, Blue and Ground, isn't it?)

  2. If I have 12V DC Adapter and it throws more than 6A current, can I use it without resistors?

  3. If the adapter throws more than 6A current, what happen to remained current? just gone away to somewhere?

  4. Can I use higher voltage adapter if I use proper resisters?

thanks in advance and sorry for my bad English! :(

  • \$\begingroup\$ Adapters do not "throw" current. The LED strips usually contain their own resistors. \$\endgroup\$
    – pjc50
    Oct 22, 2014 at 8:54
  • \$\begingroup\$ A picture would help. \$\endgroup\$
    – David
    Oct 22, 2014 at 9:03

1 Answer 1

  1. Yes, But the cathode (negative part) of the diodes in adafruits example is connected to R/G/B. Then, when you apply power to the common anode (positive side), the pin (R, G or B) you pull low to ground will light up.

  2. Your adapter doesn't just push out 6A; it is able to provide 6A at 12V. You can power any 12V device with it requiring less than 6A. Say you connect 3 diodes in parallell that consumes 20mA each, the output of the adapter will only measure 60mA.

  3. If the circuit powered by the adapter requires more than 6A, your adapter will start heating up and break.

  4. Yes, but I guess you have to read up on some basic skills before trying this, i.e be really sure of how the circuit is connected before calculating the size of your resistors. Too low R = broken circuit. Too high R = non functioning circuit.

  • \$\begingroup\$ 2. If the diodes and their series resistors are rated to pass 20mA with 12V across them, then 3 in series connected across 12V won't pass 60 mA, 3 in parallel will. \$\endgroup\$
    – EM Fields
    Oct 22, 2014 at 10:05
  • \$\begingroup\$ 2. If the diodes and their series resistors are rated to pass 20mA with 12V across them, then 12V across three of them in series won't push 20 mA through the string, 36 volts will. :-) \$\endgroup\$
    – EM Fields
    Oct 22, 2014 at 10:50
  • \$\begingroup\$ Haha, I guess I'm tired today ;) \$\endgroup\$
    – chwi
    Oct 22, 2014 at 10:51

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