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LED Christmas Lights Distance Check

LED Christmas Lights Distance Check

Since this LED Christmas light project is introducing me to quite a few new things as far as LED strips and power supplies go, I’m testing a lot things before taking the next step.  At this point, I wanted to be sure I could run sufficient power and a strong enough signal to the WS2812B LED strip.

I did a number of bench tests using a converted computer power supply that puts out 5 volts at 25 amps, and 12 volts at 15 amps.  The test LED strips were two 51-LED strips that I have assembled to fit in one peak of my roofline – at the point farthest away from the power and signal source.  For the Christmas light signal, I’m using FastLED on an Arduino Mega 2560.  I’ve been told that a Teensy will perform better than the Mega – and I’ve already purchased one – but I haven’t had time to mess with it yet.

Prior to the tests I measured voltage drop on the 100-foot 18-gauge speaker wire.  Source voltage was 5.25 volts and at the end of the line (with no load) it was 5.15 volts.

TEST 01

  • 1 LED strip powered by a 2-foot, 18-gauge, multi-strand wire (speaker wire) connection to the 5-volt source, and a 2-foot single 24-gauge wire connection to the Arduino signal pin.
  • 1 LED strip powered by a 100-foot, 18-gauge, multi-strand wire (speaker wire) connection to the 5-volt source, and a 60-foot Cat5 cable (I wanted to do longer, but only had 60 feet on hand) connection to the Arduino signal pin and the Arduino ground on one of the twisted pairs.
  • Test pattern worked.


TEST 02

  • 1 LED strip powered by a 2-foot, 18-gauge, multi-strand wire (speaker wire) connection to the 5-volt source, and a 2-foot single 24-gauge wire connection to the Arduino signal pin.
  • 1 LED strip powered by a 100-foot, 18-gauge, multi-strand wire (speaker wire) connection to the 12-volt source with a buck converter set to 5 volts just before the strip, and a 60-foot Cat5 cable connection to the Arduino signal pin and the Arduino ground on one of the twisted pairs.
  • Test pattern worked.


TEST 03

  • 1 LED strip powered by a 2-foot, 18-gauge, multi-strand wire (speaker wire) connection to the 5-volt source, and a 2-foot single 24-gauge wire connection to the Arduino signal pin.
  • 1 LED strip powered by a 100-foot, 18-gauge, multi-strand wire (speaker wire) connection to the 12-volt source with a buck converter set to 5 volts just before the strip, and a 100-foot phone extension cable connection to the Arduino signal pin and the Arduino ground on one of the twisted pairs.
  • Test pattern worked.



TEST 04

  • 1 LED strip powered by a 2-foot, 18-gauge, multi-strand wire (speaker wire) connection to the 5-volt source, and a 2-foot single 24-gauge wire connection to the Arduino signal pin.
  • 1 LED strip powered by a 100-foot, 18-gauge, multi-strand wire (speaker wire) connection to the 5-volt source, and a 100-foot phone extension cable connection to the Arduino signal pin and the Arduino ground on one of the twisted pairs.
  • Test pattern worked.



NOTE:  The Cat5 and phone extension tests failed the first time I tried them because I didn't include a connection from the Arduino Mega 2560 ground to the ground just before the WS2812B LED strip.  Once the ground was included, it worked like a charm on both the Cat5 and, surprisingly to me, on the phone extension.

NOTE:  The power wires just before the LED strips had a 2200 ohm 10-volt capacitor on them.  The signal input wire just before the LED strips had a 220 ohm resistor on them.

At this point, I think I’m going to run the LED Christmas lights farthest away from the signal and power source with 11 volts stepped down to 5 volts with buck converters just before the WS2812B strips.  The biggest reason for doing this is to “use up” some the 15 amps provided on the 12-volt source and leave as much of the 25 amps on the 5-volt for larger amount of lights near the power source.


I will also use the phone extension cable to run my signals through, since I already have a lot of it lying around – salvaged from an office renovation at my workplace many years ago.  The four wires in the extension will allow for the two signals I need at that point, and the two ground connections.  Just to be safe though, I’ll run some string alongside it, in case I ever decide to pull some Cat5 in the future.