RGB LED Strip external power source

[MrDankYT]

you dont have to tell everything is wrong that i do first you tell me i need capacitor then you tell me i dont need one, someone tell me the leds are upside down and i switch ground and 5v but you still say it's wrong if its better like a box with 3 wires think of it like one, i didn't understand what you said about taking power from led strip to the arduino nano because im only 12 and i dont know much english because im from sweden and i just try to make a fun project with arduino and i needed help but you people just say everything wrong and complain sorry

[Grumpy_Mike]

The Capacitor isn't really needed, since there should be  a big enough one in the stepdown 15v-5v  if it's a good one.

No there is not. These things are designed to supply a constant voltage under a constant current. The pulsed current produced by an LED strip is is large the capacitor in the step down converter is totally insufficient to cope with this. So yes it is really needed.

[Paul__B]

You have a power converter that supplies plenty of 5 V power to the LED strip.  The Nano operates from 5 V, so you connect the 5 V and ground from the LED strip back to the Nano to power it and there is no need for a "power bank" to supply it, that is wasteful and only complicates matters.

This diagram was fine to start with,

Just add the capacitor, the resistor, and a wire from the +5 V at the LED strip to +5V on the Nano.

As you construct it, keep the power wires from each part together as a pair, and the three wires between the LED strip and the Nano, together.

[MrDankYT]

ok have done this now because i got led strip yesterday so i dont find 2 pin switch in library for circuit but both switch turn at same time, when one is on the other is off, so switch one direction control with arduino, switch other direction its controll by phone

[Deva_Rishi]

And does it work ? (should do..)

[MrDankYT]

yes it work very cool