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hpr3123 :: Arduino controlled Christmas lights

Controlling Christmas LED lights with an Arduino

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Hosted by Archer72 on 2020-07-22 is flagged as Clean and is released under a CC-BY-SA license.
Arduino, Christmas, lights, Solid state relays. 1.
The show is available on the Internet Archive at:

Listen in ogg, spx, or mp3 format. Play now:

Duration: 00:02:50

Arduino and related devices.

In this series various contributors talk about how to use and program Arduino single-board microcontrollers and related devices.
See the Wikipedia article for details of the range of devices.

  1. Inspired by an Instructable project

  2. Started the project with Arduino Uno.

    • Found that power it with the barrel plug made audio input stable
    • Tested this theory by using USB power
    • Suspect this was due to grounding not being as good with the USB
    • This caused LED's to light even without an audio input
    • Ended up using an generic Arduino Nano to control the project
  3. Modified an audio mic preamplifier from Amazon to condition the output from the laptop music source

  4. Ran the output from this to A0 on the Arduino

  5. Split the signal out to an external speaker

  6. Used digital outputs listed in the sketch to power the LED indicators

    • For reference, a sketch is the program that the Arduino runs through a loop.
  7. Used pins 10 to 12 as AnalogWrite pin to provide the power to the solid state relays.

  8. Used a dremel to separate the power to the hot side of the two power outlets

    • Used three of the outlets to power three strings of Christmas tree LED lights.
    • Used the other outlet to power the Arduino
  9. Bonus

    • Using these particular solid state relays, there is still a 10Vac output in off state. It actually worked for good, as the lights are at a nice brightness without a music input.
    • Kindly leave a note in the comments if this is common to Solid State relays.

GY-MAX4466 Electret Microphone Amplifier

Solid State relay on Ebay

ELEGOO for Arduino Nano V3.0


My video

Sound Reactive Christmas lights on


Here is the song I meant to add, to see if it matches my video of the lights.

It is the Trans Siberian Orchestra, Carol of the Bells.


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Comment #1 posted on 2020-08-03 14:24:07 by Archer72

Funny story

I was not meaning to have a Christmas in July episode, that is just the way it turned out. It was more a matter of letting life get in the way, as the project was finished in mid December. That and I get nervous about having to short of a show, or not being interesting enough.

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